In computing, a back door is a hole in the security of a system deliberately left in place by designers or maintainers. The motivation for this is not always sinister; some operating systems, for example, come out of the box with privileged accounts intended for use by field service technicians or the vendor's maintenance programmers. Historically, back doors have often lurked in systems longer than anyone expected or planned, and a few have become widely known. The infamous RTM worm of late 1988, for example, used a back door in the BSDUNIX 'sendmail(8)' utility. Research Back door
In computing terminology, a backbone is a high-speed network that connects several powerful computers. In the USA, the backbone of the Internet is often considered to be the NSFNet, a government funded link between a handful of supercomputer sites across the country. Research Backbone
Backbone Facilities are a transmission facility designed to interconnect tributary facilities from clusters of dispersed users or devices; the viewpoint of what is a 'backbone' can range from a single building's wiring to an intercontinental network. Research Backbone Facilities
In computing, a backdoor is a secret point of entry to a computer program or computer. Legitimate backdoors may be created by a system developer, but more commonly they are used by hackers for penetrating a computer over a network. The most popular method of establishing a backdoor to a computer is through the 'Backdoor Mail Spam' in which an unsolicited email is sent to a victim with a
backdoor program attached to it. This backdoor program will be disguised (a Trojan) pretending to be perhaps a computer game or a screensaver. Further, the email may pretend to originate from a trusted source, such as the mail program of the network or a well-known computer company. When the recipient executes the attachment, the backdoor program installs itself secretly onto the computer and monitors a predefined port on the network waiting to allow a hacker in 'through the back door'. Research Backdoor
Backer by Cordes Development is a Windows utility for synchronizing and updating directories and files via a network, disk, infra-red, or cable. Backer keeps all your computers and disks up-to-date. With Backer you can: synchronize files within a work team; synchronize your notebook before you travel and your desktop afterwards; transfer files between your office and your home; backup your day's or week's work; keep current copies of system files on disk to be prepared for a crash. Research Backer
In computing, background describes a process or program that while it is running the operator can run other processes or programs, type at the keyboard etc. Research Background
In electronics, background noise is the aggregate of random noise in a sound-reproducing system, arising from such causes as radio interference, valve and other circuit noise, record scratch, etc. and not from the signal being reproduced. Research Background Noise
Background radiation is low intensity ionising radiation which is always present in the environment. Most background radiation comes from natural sources such as cosmic rays and some types of rocks (for example granite in the Earth's crust); the rest - about 13 percent - comes from artificial sources. Of the artificial sources the one that contributes most to the
background radiation is the medical use of radioactive materials: other sources are the nuclear industry and fallout from weapons tests, television screens and luminous paint. When the radiation from a specific source is measured, the background radiation must be deducted from the result to make it accurate. Research Background Radiation
In mechanics, the term backlash describes the distance through which one part of connected machinery, such as a wheel, piston, or screw, can be moved without moving the connected parts, resulting from looseness in fitting or from wear. The term also describes the jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion. Research Backlash
Baily's Beads is a phenomenon attending eclipses of the sun, the unobscured edge of which appears discontinuous and broken immediately before and after the moment of complete obscuration. It is classed as an effect of irradiation. Research Baily's Beads
A balance is an instrument employed for determining the quantity of any substance equal to a given weight. Balances are of various forms; in that most commonly used a horizontal beam rests so as to turn easily upon a certain point known as the centre of motion. From the extremities of the beam, called the centres of suspension, hang the scales; and a slender metal tongue midway between them, and directly over the centre of motion, indicates when the beam is level. The characteristics of a good balance are: 1st, that the beam should rest in a horizontal position when the scales are either empty or loaded with equal weights; 2nd, that a very small addition of weight put into either scale should cause the beam to deviate from the level, which property is denominated the sensibility of the balance; 3rd, that when the beam is deflected from the horizontal position by inequality of the weights in the scales, it should have a tendency speedily to restore itself and come to rest in the level, which property is called the stability of the balance.
To secure these qualities the arms of the beam should be exactly similar, equal in weight and length, and as long as possible; the centres of gravity and suspension should be in one straight line, and the centre of motion immediately above the centre of gravity; and the centre of motion and the centres of suspension should cause as little friction as possible. The centre of motion ought to be a knife-edge; and if the balance requires to be very delicate, the centres of suspension ought to be knife-edges also. If the balance have no tendency to one position more than another, when the scales are either loaded, empty, or off altogether, it is a proof that the centres of gravity and motion coincide, and the remedy is to lower the centre of gravity. If the beam is disturbed by a small addition of weight to either scale, and exhibits no tendency to resume the horizontal position, we may infer that the centre of gravity is above the centre of motion.
If it require a considerable excess of weight to deflect the beam from the level, we may infer either that there is too much friction at the centre of motion, or that the centre of gravity is too low. If two weights are found to be in equipoise, one being in each scale, and if, when that which is in the one scale is put into the other, there is no longer equilibrium, then we may infer that the arms of the beam are of unequal lengths. Eor purposes of accuracy, balances have occasionally means of raising or depressing the centre of gravity, of regulating the length of the arms, etc, and the whole apparatus is not unfrequently enclosed in a glass case, to prevent the heat from expanding the arms unequally, or currents of air from disturbing the equilibrium.
Of the other forms of balance, the Roman balance, or steelyard, consists of a lever moving freely upon a suspended fulcrum, the shorter arm of the lever having a scale or pan attached to it, and the longer arm, along which slides a weight, being graduated to indicate quantities. It was commonly used for weighing loaded carts, for luggage at railway-stations, etc. A variety of this, the Danish balance, has the weight fixed at the end of the lever, the fulcrum being movable along the graduated index. The spring-balance shows the weight of articles by the extent to which they draw out or compress a spiral spring. It is of service where a high degree of exactness is not required, and finds application in the dynamometer for measuring the force of machinery. Research Balance
Balata is a latex derived from the Bullet-Tree. It has properties intermediate between gutta-percha and India-rubber, making it more suitable for certain industrial purposes. It has been used in the USA as a chewing material for many years, and is used to make chewing-gum. Research Balata
A ball valve is a type of valve comprising a single or multiple balls which in all cases are caged, and rises only slightly from its seat. This type of valve is especially useful for small-capacity and high-speed pumps. Research Ball Valve
A ball-cock is a kind of self-acting stop-cock opened and shut by means of a hollow sphere or ball of metal or plastic attached to the end of a lever connected with the cock. Such cocks are often employed to regulate the supply of water to cisterns. The ball floats on the water in the cistern by its buoyancy, and rises and sinks as the water rises and sinks, shutting off the water in the one case and letting it on in the other. Research Ball-cock
A ballistic pendulum was an apparatus formerly employed for ascertaining the velocity of military projectiles, and consequently the force of fired gunpowder. A piece of ordnance was fired against bags of sand supported in a strong case or frame suspended so as to swing like a pendulum. The arc through which it vibrated was shown by an index, and the amount of vibration formed a measure of the force or velocity of the ball. Research Ballistic Pendulum
Balun is a shortened term derived from BALanced to UNbalanced transformer. A
balun is often used in radio to allow the connection of an unbalanced cable to a balanced aerial system. Research Balun
Bandoline is a gummy substance produced from gum tragacanth, quince seeds, Irish moss or Icelandmoss, with perfume added and formerly used by 19th century and early 20th century hairdressers to make the hair glossy and to fix it in position. Research Bandoline
A banner exchange is a free service designed to help website owners advertise and promote their website. By inserting a small piece of code supplied by the exchange program onto their web page, a member will display banner adverts from other exchange members, and in return, their advertising banners are displayed across the exchange network. Research Banner Exchange
Barilla was the commercial name for the impure carbonate and sulphate of soda formerly imported from Spain and the Levant. It is the Spanish name of a plant (Salsola Soda), from the ashes of which and from those of others of the same genus the crude alkali was obtained. On the shores of the Mediterranean the seeds of the plants from which it was obtained were regularly sown near the sea, and these, when at a sufficient state of maturity, were pulled up, dried, and burned in bundles in ovens or in trenches. The ashes, while hot, were continually stirred with long poles, and the saline matter they contain formed, when cold, a solid mass, almost as hard as stone. To obtain the carbonate of soda it was only requisite to lixiviate the barilla in boiling water, and evaporate the solution. British barilla or kelp is a still more impure alkali formerly obtained from burning seaweeds. Research Barilla
Barium is a silver-white, malleable, toxic, bivalent metallic element of the alkaline-earth group that occurs only in combination - it is strongly reactive to air and has to be stored under mineral oil. It has the symbolBa. Barium dissolves in water, but does not dissolve in sulphuric acid, rather the sulphuric acid causes a protective layer of barium sulphate to form around the barium. Research Barium
A Barker's Mill is an apparatus based upon the principal of the hydraulic tourniquet. It consists of a vessel containing water and free to rotate about vertical axis. Near its base are provided outlet pipes through which the water is discharged horizontally, in a direction tangential to a circle having its centre at the axis of rotation of the vessel. The mill operates upon the reaction principle, the unbalanced pressures at the discharge orifices causing the vessel to rotate. A horizontal turbine wheel having curved outlet pipes around its periphery acts upon this principle. Research Barker's Mill
BARKER'S MILL
A Barker's mill or Scottish turbine is a hydraulic machine on the principle of what is known as the hydraulic tourniquet. This consists of an upright vessel free to rotate about a vertical axis, and having at its lower end two discharging pipes projecting horizontally on either side and bent in opposite directions at the ends, through which the water is discharged horizontally, the direction of discharge being mainly at right angles to a line joining the discharging orifice to the axis. The backward pressures at the bends of the tubes, arising from the two issuing jets of water, cause the apparatus to revolve in an opposite direction to the issuing fluid. Research Barker's Mill
A barometer is a device for measuring atmospheric pressure and thus determining changes in the weather, the height of mountains, and other phenomena. The basic principle behind the barometer is the discovery in 1643 by Torricelli, that atmospheric pressure might be counterpoised by a column of mercury standing as high in proportion to the thirty-four feet that water in similar circumstances stands, as the specific gravity of water is to that of mercury. Pascal confirmed the conclusions of Torricelli in 1645; six years afterwards it was found by Perrier that the height of the mercury in the Torricellian tube varied with the weather; and, in 1665, Boyle proposed to use the instrument to measure the height of mountains. Various types of barometer have been invented, among the most common being the cistern barometer, Gay-Lussac's barometer and the aneroid barometer.
The common or cistern barometer, which is a modification of the Torricellian tube, consists of a glass tube 33 inches in length and about one-third of an inch in diameter, hermetically sealed at the top, and having the lower end resting in a small vessel containing mercury, or bent upwards and terminating in a glassbulb partly occupied by the mercury and open to the atmosphere. The tube is first filled with purified mercury, and then inverted, and there is affixed to it a scale to mark the height of the mercurial column, which comparatively seldom rises above 31 or sinks below 28 inches. In general the rising of the mercury presages fair weather, and its falling the contrary, a great and sudden fall being the usual presage of a storm. The weather-points on the ordinary barometric scale are as follows: - At 28 inches, stormy weather; 28.5, much rain or snow; 29, rain or snow; 29.5, changeable; 30 fair or frost; 30.5, settled fair or frost; 31. very dry weather or hard frost. Certain attendant signs, however, have also to be noted: thus, when fair or foul weather follows almost immediately upon the rise or fall of the mercury, the change is usually of short duration; while if the change of weather be delayed for some days after the variation in the mercury, it is usually of long continuance. The direction of the wind has also to be taken into account.
The siphon barometer consists of a bent tube, generally of uniform bore, having two unequal legs, the longer closed, the shorter open. A sufficient quantity of mercury having been introduced to fill the longer leg, the instrument is set upright, and the mercury takes such a position that the difference of the levels in the two legs represents the pressure of the atmosphere. In the best siphon barometers there are two scales, one for each leg, the divisions on one being reckoned upwards, and on the other downwards from an intermediate zero point, so that the sum of the two readings is the difference of levels of the mercury in the two branches.
The wheel barometer is the one that was most commonly used for domestic purposes before the computer age. It was far from being accurate, but it was often preferred for ordinary use on account of the greater range of its scale, by which small differences in the height of the column of mercury were more easily observed. It usually consisted of a siphon barometer, having a float resting on the surface of the mercury in the open branch, a thread attached to the float passing over a pulley, and having a weight as a counterpoise to the float at its extremity. As the mercury rose and fell the thread and weight turned the pulley, which again moved the index of the dial.
The mountain barometer was a portable mercurial barometer with a tripod support and a long scale for measuring the altitude of mountains. To prevent breakage, through the oscillations of such a heavy liquid as mercury, it was usually carried inverted, or it was furnished with a movable basin and a screw, by means of which the mercury could be forced up to the top of the tube. for delicate operations, such as the measurement of altitudes, the scale of the barometer was furnished with a nonius or vernier, which greatly increased the minuteness and accuracy of the scale. For the rough estimate of altitudes the following rule was sufficient: - As the sum of the heights of the mercury at the bottom and top of the mountain is to their difference, so is 52,000 to the height to be measured, in feet. In exact barometric observations two corrections require to be made, one for the depression of the mercury in the tube by capillary attraction, the other for temperature, which increases or diminishes the bulk of the mercury. In regard to the measurement of heights the general rule is to subtract the ten-thousandth part of the observed altitude for every degree of Fahrenheit above 32 degrees.
In the aneroid barometer, as its name implies (the name coming from the Greek a, not, neros, liquid), no fluid was employed, the action being dependent upon the susceptibility to atmospheric pressure shown by a flat circular metallic chamber from which the air had been partially exhausted, and which has a flexible top and bottom of corrugated metal plate. By an ingenious arrangement of springs and levers the depression or elevation of the surface of the box was registered by an index on the dial, by which means it was also greatly magnified, being given in inches to correspond with the mercurial barometer. Aneroids are, however, generally less reliable than mercurial barometers, with which they were recommended to be frequently compared. Research Barometer
In nuclear physics, a baryon is a heavy subatomic particle made up of three indivisible elementary particles called quarks. The baryons form a subclass of the hadrons and comprise the nucleons (protons and neutrons) and hyperons. Research Baryon
A bascule bridge is one which rotates upon a horizontal axis. The roadway is hinged to allow it to be drawn up to allow the passage of vessels. Research Bascule Bridge
In chemistry, base is a term applied to those compound substances which unite with acids to form salts. The most important bases are oxides of metals, and when brought in contact with acids their oxygen combines with the hydrogen of the acid to form water. They are divided into several sections, of which the most important are the alkalies. These substances are the hydrates of the so-called alkaline metals, and may be compared to water in which part of the hydrogen is replaced by a metallic radicle. Potash, for instance, is the hydrate of the metal potassium. The alkalies are readily soluble in water, restore the blue colour of reddened litmus, and give a green with red cabbage, dahlia, and other vegetable blues, and convert the yellow of turmeric into a brownish red. Most of the bases, however, are insoluble in water, and without any effect on vegetable colours. Research Base
Basys is a client-server computer system used by almost all broadcasting organisations for storing and manipulating newsroom information including: wire stories, show scripts, assignment lists and contact files. The main database runs on a UNIX file server (usually two or three mirrored computers) supporting a number of client workstations which are either dumb terminals (VT) or DOS/ Windows based PCs. The system is used by journalists to write the news stories which are then broadcast. Basys is very configurable, and many organisations use customised versions - the BBC's version being called 'Edit'. Research Basys
A bathometer is an apparatus invented by William Siemens in 1861 to measure the depth of water without submerging a sounding line. Its action depends on the diminution of the effect of gravitation on the surface of the water as compared with its effect on the earth, owing to the mass of water (of less density) which replaces earth (of greater density); which is duly registered. Research Bathometer
Bathybius was a name given by Huxley to a supposed organism found in some preserved examples of deep-sea ooze obtained by Captain Dayman in 1857, while dredging in HMS Cyclops, in connection with the laying of the Atlantic cable. Huxley's description was published in the Quarterly Journal of Microscopical Science in 1868. Eventually it was shown by the Challenger that the substance in question was nothing but a precipitate of gelatinous calcium sulphate thrown down by the addition of strong alcohol to deep-sea ooze. Research Bathybius
Battery Watch is a computer program for laptop computers. Because laptop computers run on batteries, they sometimes lose power at inconvenient times. Battery Watch monitors the amount of power left in the battery of a laptop computer. Although many laptops have power indicators, they may only give a 10-15 minute warning.
Battery Watch lets you check power level at any time, so you'll never be caught off-guard.
Battery Watch is a Terminate and Stay Resident (TSR) program which is activated by a hotkey. The hotkey displays the power gauge on-screen showing immediately how much time is left on the machine. The hotkey can be changed so it does not interfere with other RAM-resident programs that use the same key. Research Battery Watch
Baud is a unit of computer etc. signalling speed. The speed in Baud is the number of discrete conditions or signal elements per second. If each signal event represents only one bit condition, then Baud is the same as bits per second. Baud does not equal bits per second. Research Baud
The BBC Master Compact was a British personal computer launched in 1986 by Acorn Computers, based on the 65C12 processor running at 2 Mhz. The BBC Master Compact was fitted with 128 kb of RAM and ran the BBC BASIC ADFS operating system. The
BBC Master Compact was available with a 12-inch green monochrome or 8-colour monitor and had a display resolution of 640 x 256 pixels or 40 or 80 x 20 character cells. The BBC Master Compact used an external 640 kb 3.25 inch floppy disk drive for storage. Research BBC Master Compact
The BBC Microcomputer was developed in 1982 in the UK by Acorn for the BBC. The first versions were developed from Acorn's earlier microcomputers, the Electron and the Atom, and based on Rockwell's 6502 microprocessor. The computer was also the beneficiary of UK Government funding to schools, which were able to buy the BBC Micro at reduced prices. As a result, it became the dominant microcomputer in British schools. The BBC Micro was a highly advanced microcomputer for its time, with full support for disc drives and network connection. Its immediate successor, the BBC Master, also sold well to schools, but was too expensive for home use and unsuccessful in the business market. In 1998 the BBC World Service was still using a BBC Microcomputer in one of the studios for editing scripts. Research BBC Microcomputer
A BBS (Bulletin Board System) is a communicating computer equipped so as to provide informational messages, file storage and transfer and a degree of message exchange to dial-up data terminal or personal computer users. Research BBS
BCD (Binary Coded Decimal) is a binary-coded notation in which each decimal digit of a number is expressed in binary form; Example: 23 decimal is 10111 in binary, and 0010 0011 in BCD. Research BCD
In scientific terms, a beam is a stream of light energy, and may be represented by a number of rays which may be either diverging, converging or parallel. Research Beam
The Bearcat DX1000 was a Japanese made general coverage receiver manufactured from 1983 to 1984 and providing coverage from 10khx to 30mhz in AM, SSB, CW and FM modes. Although rich in features, the receiver was prone to overloading by strong signals and. Research Bearcat DX1000
A Beat-frequency Oscillator (B.F.O.) is a device for generating oscillations of approximately sinusoidal waveform by combining two radio-frequency electrical oscillations of different frequencies. Research Beat-frequency Oscillator
Bebeerine is the active principle of the bark of the bebeeru or green-heart tree of Guiana, analogous to quinine, and used to some extent for similar purposes. Research Bebeerine
Becquerel Rays was a name originally given to the radiations emitted by radioactive substances, and now distinguished as Alpha Rays, Beta Rays, and Gamma Rays. Becquerel Rays were so named from their discoverer, the eminent French physicist, Henri Becquerel. They were first detected in 1896, as proceeding from uraniumsalts. Research Becquerel Rays
Bees'-wax is a solid fatty substance secreted by bees, and containing in its purified state three chemical principles - myricin, cerin, and cerolein. It is not collected from plants, but elaborated from saccharine food in the body of the bee. It is used for the manufacture of candles, for modelling, polishing wooden furniture and in many minor processes. Research Bees'-wax
In machinery, a bell-crank is a rectangular lever by which the direction of motion is changed through an angle of 90 degrees, and by which its velocity-ratio and range may be altered at pleasure by making the arms of different lengths. It is much employed in. machinery, and is named from its being the form of crank employed in changing the direction of the bell-wires of house-bells. Research Bell-Crank
A Bellini-Tosi aerial is an arrangement of two large fixed-frame aerials mounted at right angles to each other and used in conjunction with a radiogoniometer in radio direction finding. Research Bellini-Tosi Aerial
Bellows are an instrument or machine for producing a strong current of air, and principally used for blowing fires, either in private dwellings or in forges, furnaces, mines, etc. Bellows are so formed as, by being dilated and contracted, to inhale air by an orifice which is opened and closed with a valve, and to propel it through a tube upon the fire. It is an ancient contrivance, being known in Egypt, India, and China many ages ago, while forms of it are used among native tribes in Africa. Bellows of very great power are called blowing-machines, and were formerly wrought by machinery driven by steam. Research Bellows
Originally, a benchmark was a surveying term. A land surveyor, when taking levels, required some fixed point or datum as a standard of height by which to regulate and verify measurements and operations. This basic point was indicated by a mark resembling a bench (in ordnance they took the form of a broad arrow), hence the term benchmark.
In later parlance benchmarks became understood as a relative measure of performance, often a standard or fixed value against which other data can be compared. In computing terms they are considered (by hackers) as an inaccurate measure of computer performance. 'In the computer industry, there are three kinds of lies: lies, damn lies, and benchmarks.' Well-known ones include Whetstone, Dhrystone, Rhealstone, the GabrielLISP benchmarks, the SPECmark suite, and LINPACK. Research Benchmark
Benzene, benzine or benzol is a a liquid hydrocarbon obtained from coal-tar or distillate of petroleum obtained from benzol by treating it with sulphuric acid and then distilling, used as a solvent in dry cleaning and painting. Benzene was discovered by Faraday in the oils of portable gas in 1825 and obtained by Mitscherlich from benzoic acid in 1834, and by Mansfield from coal tar in 1848 (he also died as the result of burns sustained while experimenting with benzene). It has the formulae CgHg and is quite colourless, of a peculiar agreeable odour and is used by manufacturers of india-rubber and gutta-percha, on account of its great solvent powers, in the preparation of varnishes, also for removing grease from fabrics, gloves, etc. It is the parent substance for most of the aniline dyes and for other substances, e.g. saccharin. It is inflammable, burning with a very smoky flame. Research Benzene
Benzoic acid occurs naturally in berries and vegetables, but is commercially produced by chemical synthesis and used in food as an anti-fungal and anti-bacterial agent. It may cause migraine attacks when consumed with coal-tar derived dyes. Research Benzoic Acid
Benzo[a]pyrene (B[a]P) is one of the polycyclic aromatic hydrocarbon (PAH) compounds. Because it is formed when petrol, rubbish, or any animal or plant material is burned, it is usually found in smoke and soot. Benzo[ a]pyrene is also found in the coaltar pitch that is used to join electrical parts together and in creosote. Research Benzo[a]pyrene
Benzyl benzoate is a colourless, faintly aromatic liquid used chiefly as a fixative and solvent in the manufacture of flavourings and perfume and in medicine in the treatment of certain skin conditions. Research Benzyl benzoate
Beryllium is a steel-grey, light, strong, brittle, toxic, bivalent metallic element used chiefly as a hardening agent in alloys. It has the symbol Be. Research Beryllium
A bespoke browser is a web browser which has been customised, often, for example to add functionality peculiar to a particular web site. For example a bespoke web browser may be a modified version of Microsoft's Internet Explorer with an added toolbar for quickly accessing pages at a specific web site. Bespoke browsers are popularly made freely available as a form of viral marketing by companies. Research Bespoke Browser
The bessemer converter is a process for making cheap steel. Basically, impurities are removed from the pig iron by blasting air through the molten metal and adding lime to remove phosphorus from the metal. The process takes about twenty minutes. Research Bessemer converter
Beta Particles are electrons travelling at velocities up to 99 percent of the velocity of light, such as are emitted from the nuclei of the atoms of radioactive materials. Research Beta Particles
A betatron is an apparatus for accelerating electrons to very high velocities by means of a periodic magnetic field, thus producing 'artificial' beta rays. Research Betatron
In mechanics, a bevel gear is a kind of gear in which the two wheels working together lie in different planes, and have their teeth cut at right angles to the surfaces of two cones whose apices coincide with the point where the axes of the wheels would meet. Research Bevel Gear
A bevel-square is a square, the blade of which is adjustable to any angle in the stock, and retained at any 'set' by a clamping screw. Research Bevel-Square
A bicarbonate indicator is a PHindicator sensitive enough to show a colour change as the concentration of the gas carbon dioxide increases. The indicator is used in photosynthesis and respiration experiments to find out whether carbon dioxide is being liberated. The initial red colour changes to yellow as the pH becomes more acidic. Carbon dioxide, even in the concentrations found in exhaled air, will dissolve in the indicator to form a weak solution of carbonic acid, which will lower the pH and therefore give the characteristic colour change. Research Bicarbonate Indicator
Bidery, named after the town of Bider in India, is an alloy, primarily composed of copper, lead, tin, to every 3 oz. of which 16 oz. of spelter (zinc) are added. Many articles of Indian manufacture, remarkable for elegance of form and gracefully-engraved patterns, are made of it. It is said not to rust, to yield little to the hammer, and to break only when violently beaten. Articles formed from it are generally inlaid with silver or gold and polished. Research Bidery
Biela's Comet was discovered by Biela, an Austrian officer, in 1826. Its periodic time was determined as 6 years 38 weeks. It returned in 1832, 1839, 1846, and 1852. On the latter two occasions it was in two parts, each having a distinct nucleus and tail. It has not since been seen as a comet; but in 1872, 1879, and 1885, when the earth passed through the comet's track, immense flights of meteors were seen, which have been connected with the broken-up and dispersed comet. Research Biela's Comet
Billon is an alloy of copper and silver, in which the former predominates, formerly used in some countries for coins of low value, the object being to avoid the bulkiness of pure copper coin. Research Billon
A binary search is a fast system of searching a sorted list. The basic principle is that each comparison divides the remaining list into two. The first search commences at the middle of the list, and determines if the desired key is in the first or last half. The next comparison occurs half way through the half determined by the previous comparison, and so on until either a matching key is located, or the search fails because no matching key is included in the list. Research Binary Search
In algebra, a binominal is a quantity consisting of two terms or members, connected by the sign + or -. The binomial theorem, is the celebrated theorem given by Sir Isaac Newton for raising a binomial to any power, or for extracting any root of it by an approximating infinite series. Research Binominal
Biogenesis is the history of life development generally and specifically, that department of biological science which speculates on the mode by which new species have been introduced; often restricted to that view which holds that living organisms can spring only from living parents. Research Biogenesis
Biogeography is the science of the study of the geographical distribution of living organisms. It is based primarily on geological research, the findings of palaeontologists, and evolutionary systematics - notably comparative morphology. Biogeography divides the earth into regions (regional
biogeography) made on the basis of historical ecology, and includes the Megagaea kingdom which is subdivided into the Holarctic biotic region which is further divided into the Palaearctic and the Nearctic sub-regions; the Oriental biotic region; the Afrotropical biotic region which is subdivided into the African sub-region and the Madagascan sub-region; the Neogaea kingdom which contains the Neotropical sub-region; the Notogaea kingdom which contains the Australasian region which is further divided into the Continental Australian sub-region, the New Zealand sub-region and the Polynesian sub-region. Research Biogeography
Biology is the science of life dealing with the morphology, physiology, anatomy, behaviour, origin and distribution of living organisms. Research Biology
Bistre (Bister) is a warm-brown pigment extracted from the soot of wood, especially beech. It furnishes a fine transparentwash, but is mainly used in monochrome sketching in the same manner as sepia or Indian Ink. Research Bistre
In printing, a bit image is a form of image where shapes are comprised of dots. The resolution of the bit image is limited by the size of the dots. Research Bit Image
In computing, bitmaps are images comprised of an array of colour values. Each colour value determines the colour of one pixel in the image. For black and white images, the colour value of each pixel can be expressed in a single bit of information as just 0 or 1. For colour images, more bits per pixel are required, eight bits for images with up to 256 colours, sixteen bits for images with up to 16636 colours and so on. Bitmaps are the only choice of image format for photographic images, but generate larger file sizes than vector graphics and are less resizable. Research Bitmaps
Bitnet is an international computer network linking colleges and universities, similar to Usenet but using a different set of technical protocols for distributing information. It offers hundreds of discussion groups, comparable in scope to Usenet newsgroups.
Bitnet messages are sent to your mailbox, just as with a mailing list. However, where mailing lists are often maintained by a person, all Bitnet discussion groups are automated - you subscribe to them through messages to a 'listserver' computer. Research Bitnet
Bittern is the syrupy residue from evaporated sea-water after the common salt has been taken out of it. It is used in the preparation of Epsom salts (sulphate of magnesia), of Glauber's salt (sulphate of soda), and contains also chloride of magnesium, iodine, and bromine. Research Bittern
Black Japan is a bituminous black paint made from asphaltum cooked with oil and blended with copalvarnish, thinned with turpentine. Black Japan is heat resistant, and was used as a stoving enamel and for painting radiators. Research Black Japan
The Black Swan HTML editor is a quick, powerful, small, inexpensive, and easy-to-use HTML editor for the Windows operating system, able to design very sophisticated Web pages and HTML help files.
Black Swan supports HTML 4.0 and all Netscape Navigator and Internet Explorer tags and attributes. For beginners, Black Swan provides an Internet overview and explains step by step how to design and publish Web pages. Features include a tag inspector, several wizards, a table builder, a link manager, professionally predesigned templates, search capabilities, bookmarks, and more. Research Black Swan
Bleaching is the act or art of freeing textile fibres and fabrics and various other substances (such as materials for paper, ivory, wax, oils) from their natural colour, and rendering them perfectly white, or nearly so.
The ancient method of bleaching by exposing the fabrics, etc, to the action of the sun's rays, and frequently wetting them, had been nearly superseded by the start of the 20th century, at least where the business is carried on on the large scale, more complicated processes in connection with powerful chemical preparations being then employed. Among the latter the chief are chlorine and sulphurous acid, the latter being employed more especially in the case of animal fibres (silk and wool), while cotton, flax, and other vegetable fibres are operated upon with chlorine, the bleaching in both cases being preceded by certain cleansing processes.
The use of chlorine as a bleaching agent was first proposed by Berthollet in 1786, and shortly afterwards introduced into Great Britain, where it was first used simply dissolved in water, afterwards dissolved in alkali, and then in the form of bleaching-powder, commonly called chloride of lime, the manufacture of which was patented by Mr. Tennant of St Rollox. Glasgow, in 1799.
In calico bleaching the preliminary process is singeing by passing the fabric over red-hot plates or through a gas-flame to remove the downy pile and short threads from the surface of the cloth. The goods next pass to the liming process, when they are uniformly and thoroughly impregnated with a supersaturated solution of lime. The next process is the bowking or boiling for several hours, after which they are washed. They are then soured by being passed through a solution of hydrochloric acid for the purpose of dissolving any traces of free lime which may have been left in the washing, and to decompose the calcareoussoap formed by the bowking process. After boiling in kiers with a solution of soda-ash and rosin and another washing, the cloth is ready for the processes of chemicking or liquoring with bleaching-powder, and white-souring with a very dilute sulphuric acid. Another thorough washing concludes the operations of bleaching proper, after which the cloth goes through various finishing processes. Modifications of the same processes are adopted in bleaching linen, wool, silk, etc. Research Bleaching
Blister-steel is iron bars which, when converted into steel, have their surface covered with blisters, probably from the expansion of minute bubbles of air. Steel is used in the blister state for welding to iron for certain pieces of mechanism, but is not employed for making edge-tools. It requires for this purpose to be converted into cast or shear steel. Research Blister-Steel
A block is a mechanical contrivance consisting of one or more grooved pulleys mounted in a casing or shell which is furnished with a hook, eye, or strap by which it may be attached to an object, the function of the apparatus being to transmit power or change the direction of motion by means of a rope or chain passing round the movable pulleys. Blocks are single, double, treble, or fourfold, according as the number of sheaves or pulleys is one, two, three, or four. A running block is attached to the object to be raised or moved; a standing block is fixed to some permanent support. Blocks also receive different denominations from their shape, purpose, and mode of application. They are sometimes made of iron as well as of wood. Blocks to which the name of dead-eyes has been given, are not pulleys, being unprovided with sheaves. Research Block
In computing, a block mode file is a file whose contents are buffered, allowing for asynchronous writes on the underlying hardware and for reads to occur at the same time and not to read again what is already in the buffer. Research Block Mode File
In smelting, bloom is the name given to a lump of puddled iron, which leaves the furnace in a rough state, to be subsequently rolled into the bars or other material into which it may be desired to convert the metal. The name is also applied to a lump of iron made directly from the ore by a furnace called a 'bloomery.' Research Bloom
A blow-pipe is an instrument by which a current of air or gas is driven through the flame of a lamp, candle, or gas jet, and that flame directed upon a mineral substance, to fuse or vitrify it, an intense heat being created by the rapid supply of oxygen and the concentration of the flame upon a small area. In its simplest form, the blow-pipe is merely a conical tube of brass, glass, or other substance, usually about 18 cm long and 2 cm in diameter at one end, and tapering so as to have a very small aperture at the other, within 5 cm or so of which it is bent nearly to a right angle, so that the stream of air may be directed sideways to the operator. The name is turned to a horizontal direction, assumes a conical shape, and consists of two parts of different colours.
The greatest heat is obtained at the tip of the inner blue flame. Here the substance subjected to it is burned or oxidized, a small piece of lead or copper, for instance, being converted into its oxide. Hence the name of the oxidizing flame. By shifting the substance to the interior blue flame, which is wanting in oxygen, this element will be abstracted from the substance, and a metallic oxide, for instance, will give out its metal; hence this is called a reducing flame. Thus various minerals can be either oxidized or reduced at pleasure, and the pipe forms a ready test in the hands of the mineralogist, who may use fluxes along with substances tested, watch how they colour the flame, what vapour they give out, etc.
The blow-pipe may be provided with several movable nozzles to produce flames of different sizes. The current of air is often formed by a pair of bellows instead of the human breath, the instrument being fixed in a proper frame for the purpose. The most powerful blow-pipe is the oxyhydrogen or compound blow-pipe, an instrument in which oxygen and hydrogen (in the proportions necessary to form water), propelled by hydrostatic or other pressure, and coming from separate reservoirs, are made to form a united current in a capillary orifice at the moment when they are kindled. The heat produced is such as to consume the diamond and to dissipate in vapour or in gaseous forms most known substances. The blowpipe is used by goldsmiths and jewellers in soldering, by glass-workers in sealing the ends of tubes, etc, and extensively by chemists and mineralogists in testing the nature and composition of substances. Research Blow-Pipe
A Blue Box is an electronic apparatus used fraudulently to synthesize signals, gaining access to the toll network for the placement of telephone calls without charge. Research Blue Box
The BNC (Bayonet Neill Concelman) is a form of quick connect/disconnect RF connectors, characterised by two bayonet lugs on the female connector which ensure a secure connection that will not easily fall apart or be accidentally pulled out. The BNC connector was developed during the late 1940's as a miniature version of the Type C connector. BNC connectors are popularly used in computer networks to join equipment together with 50 ohm or 75 ohmethernetco-axial cable. Research BNC
Bode's Law is the name given to an arithmetical formula, previously made known by Johann Kepler and Titius of Wittenberg, expressing approximately the distances of the planets from the sun. It assumes the series 0, 3, 6, 12, 24, 48, 96, etc, each term after the second being double the preceding term; to each term 4 is added, producing the series 4, 7, 10, 14, 28, 56, 100, &c. These numbers are, with the exception of 28, roughly proportional to the distances between the planets and the sun. The law has no theoretical foundation. Research Bode's Law
To boil is to heat a fluid up to the point at which it is converted into vapour. The conversion takes place chiefly at the point of contact with the source of heat, and the bubbles of vapour rising to the surface, and breaking there, produce the commotion called ebullition. At the ordinary atmospheric pressure ebullition commences at a temperature which is definite for each liquid. The escape of the heated fluid in the form of vapour prevents any further rise of temperature in an open vessel when the boiling point has been reached. The exact definition of the boiling-point of a liquid is 'that temperature at which the tension of its vapour exactly balances the pressure of the atmosphere.' The influence of this pressure appears from experiments. In an exhausted receiver the heat of the human hand is sufficient to make water boil; while, on the contrary, in Papin's digester, in which it is possible to subject the water in the boiler to a pressure of three or four atmospheres, the water may be heated far above the normal boiling point without giving signs of ebullition. From this relation between the ebullition of a liquid and atmospheric pressure the heights of objects above sea-level may be calculated by comparing the actual boiling point at any place with the normal boiling point.. The boiling-point of water as marked on Fahrenheit's thermometer is 212 degrees; on the Centigrade, 100 degrees; on the Reaumur, 80 degrees. Ether boils at about 96 degrees Fahrenheit, mercury at 662 degrees Fahrenheit. Research Boil
Boiler is the name applied to any vessel for boiling large quantities of liquor in, but most commonly used as the designation of a metallic vessel in which water is converted into steam by the agency of fire, the steam being intended by its expansive force to give motion to a steam-engine, or to be used for a variety of manufacturing purposes. Around 1900 boilers were generally constructed of mild steel, having a tensile strength of about 28 tons per square inch. In old locomotive boilers the fire-boxes are almost always constructed of copper, but in some cases, especially in America, mild steel was used here also. The tubes of locomotive boilers were of brass; those of water-tube boilers mostly of mild steel. The tubes of ordinary marine boilers are usually of wrought iron or mild steel.
Boilers may be grouped in two classes, namely, shell or tank boilers and water-tube boilers. The former consist of a large shell or tank, usually cylindrical, with flat ends. This shell contains the water and steam, so that the whole shell is exposed to the full pressure of the steam. In some cases the furnaces are external, but generally they are contained within the shell. Boilers may also be classified as flue boilers and multitubular boilers, and the latter may be again subdivided into fire-tube and water-tube boilers. Flue boilers are so called because they have large internal flues passing through them and traversed by the products of combustion. In fire-tube boilers the products of combustion pass through a large number of tubes of small diameter, whereas in water-tube boilers the water flows through the tubes, and the products of combustion flow over the outsides of the tubes.
Cornish and Lancashire boilers are examples of shell boilers of the flue type. The Lancashire boiler was 20 or 30 feet long, and 7 or 8 feet in diameter. Within it were two cylindrical flues, at the front ends of which were the two furnaces. Conical 'Galloway tubes' were usually fitted into the internal flues for the purpose of improving the circulation of the water. At the rear end of the fire-grate was a firebrick bridge, which served to prevent the fuel from falling over the end of the grate, but its main object was to cause the gases to mix more rapidly in order to facilitate rapid and complete combustion. The boiler was cased in brickwork, so built as to form external flues at the sides and beneath. The products of combustion, after leaving the internal flues, passed down to the bottom flue, along which they flowed to near the front end of the boiler. They then flowed through the side flues to the rear end, and thence into the flue leading to the economizer or to the chimney.
Marine and locomotive boilers were multitubular fire-tube boilers. Marine boilers, also called Scotch boilers, were single-ended or double-ended ; that is, they had furnaces at
one end only or at both ends. The furnaces were in cylindrical flues communicating with internal combustionchambers, from which there were a large number of return tubes above the flues leading to the uptake. In a locomotive boiler it was usual to have a firebrick arch dividing the fire-box into two compartments, the upper of which served as a combustion-chamber. The gases flowed from the fire-box through the small-diameter tubes to the smoke-box at the front end. As a high chimney could not be used, there had to be an artificial or forced draught, and this was always obtained by means of a steam blast, the exhaust steam from the engine cylinders being used for the purpose.
Water-tube boilers, also known as tubulous boilers, have been arranged in three classes, namely: (1) those with limited circulation, (2) those with free circulation, (3) those with accelerated circulation. The special feature of the first class, of which the Belleville boiler is the type, is the use of tubes rising in successive coils or folds, each receiving water at the lower end and discharging steam and water at the upper. The circulation is limited to what is necessary to replace the water evaporated, and there is no water-reservoir. Boilers of the second class, those of free circulation, have horizontal or slightly inclined generating tubes connecting two flat vertical water-spaces. The principal kinds in use around 1900 were the Niclausse, the Babcock and Wilcox the Durr, and the D'Allest. In boilers of accelerated circulation there are vertical tubes of various shapes connecting horizontal reservoirs, generally of a cylindrical shape. The water is returned from the top steam-drum to the water-drum at the bottom by large down-take tubes. The principal examples of this type of boiler are the Thornycroft, the Yarrow, the Normand, the Normand-Sigaudy, and the Stirling. Water-tube boilers of all three classes were being used to an increasing extent in war-vessels and in the mercantile marine from the start of the 20th century, and some kinds of the first two types were at the same time displacing shell boilers on land, especially in electric light and power stations. They require more careful stoking than a Lancashire boiler, but were less liable to explosion, and it was felt around 1900 that in densely peopled districts no other type should be allowed.
In the 19th century the Belleville boiler was more used in naval vessels than any other water-tube boiler, but a special British admiralty committee condemned it in 1904, and recommended the Yarrow and the Babcock and Wilcox.
A Green's economizer was an arrangement of vertical cast-iron tubes which was generally attached to Lancashire boilers in order to heat the feed-water by means of the products of combustion after they left the boiler. The products of combustion then rounded the outsides of these tubes, and the tubes were kept clean by automatic scrapers, which continuously removed the soot from them. The advantages of superheated steam are now generally recognized, and superheaters for supplying heat to the steam after it leaves the boiler, were often added to boilers. Mechanical stokers were also devised. The principal boiler fittings are as follows; pressure-gauges, to show the pressure of steam; safety-valves, of which there should be two on each boiler, one beyond the attendant's control; stop-valves, controlling the passage of steam from the boiler to the steam-piping; separators, for drying the steam; water-gauges, showing the water-level; feed check-valves, for regulating the supply of water; also automatic feed-water regulators, injectors, and feed-pumps. Research Boiler
A bolometer is an electrical instrument, invented by Langley, which is sensitive to radiant heat, and who used it to make discoveries in the ultra red rays of the spectrum. Research Bolometer
A bolster is the perforated plate in a punching machine on which anything rests when being punched. In cutlery, the bolster is that part of a knife blade which abuts upon the end of the handle. The term is also applied to the metallic end of a pocket-knife handle. Research Bolster
In computing, a bootdisk is a bootable floppy disk containing the code required to load the operating system from either the floppy disk, or more usually from a separate hard disk. Research Bootdisk
A bootstrap loader (boot) is a computer input routine in which pre-set operations are placed into a computer that enable it to get into operation whenever a reset condition occurs; in electronic PBXs this may be called Automatic Program Loading or a similar term; in personal computers it is the sequence that searches predetermined disks for a Command Interpreter program, then a Configure System file; finally an Autoexecution Batch file. Research Bootstrap Loader
Borax or sodium tetraborate has long been obtained under the name of tincal, from India, the main source being not India but a series of lakes in Tibet. As imported it was in small pieces of a dirty yellowish colour, and was covered with a fatty or soapy matter. Tincal, which contains various impurities, was formerly the only source of borax; but besides Tuscany other sources of boric acid, more particularly in North and South America, and the salt mines at Stassfurt, etc, in Germany, were rendered available. North America yields large quantities, there being rich deposits of borax and boracic minerals on the Pacific slope. Pure borax forms large transparent six-sided prisms, which dissolve readily in water, effloresce in dry air, and when heated melt in their water of crystallization, swell up, and finally fuse to a transparentglass.
Borax has a variety of uses. In medicine it is employed in ulcerations and skin diseases, and its cleansing properties render it useful for various domestic purposes. It has valuable antiseptic and disinfecting properties, and is now much used for the preservation of meat, fish, and milk, especially meat. It is also employed in the soldering of metals, and in making fine glaze for porcelain, as it renders the materials more fusible. It is used as an ingredient of enamels, and in making beads, glass, and cement. It is also one of the mordants employed in calico-printing. Research Borax
Boric acid or boracic acid is a compound of boron, hydrogen and oxygen found naturally as a saline incrustation in some volcanic regions, is an ingredient in many minerals, and is contained in the steam which, along with sulphureous exhalations, issues from fissures in the soil in Tuscany.. It is also known as acidum boricum, it is widely used as an eyewash. The acid forms white, shining, scaly crystals, which on heating melt into a transparent mass, when cooled resembling glass. It dissolves in water, and has a slight acidtaste; it colours blue litmus purple, and the yellow colouring matter turmeric brown. The chief use of the acid is as a source of borax, the biborate of sodium. Research Boric acid
Boron is a trivalent metalloid element found in nature only in combination, often in borates or silicates (such as in borax). Boron is used in metallurgy and nucleonics, being very important in nuclear reactors. It has the symbol B and is a dark brown or green amorphous powder, which stains the skin, has no taste or odour, and is only slightly soluble in water. It combines directly with oxygen, chlorine, nitrogen, etc. Boron has been obtained crystalline in an impure state, and is then nearly as hard as diamond, in the form of dust being used for polishing. Research Boron
Botany or phytology is the science of the vegetable kingdom. Plants may be studied from several different points of view. The consideration of their general form and structure, and the comparison of these in the various groups from the lowest to the highest, constitutes morphology. Anatomy and histology treat respectively of the bulkier and the more minute internal structure of the parts, and physiology of their functions. Systematic botany considers the arrangement of plants in groups and sub-groups according to the greater or less degree of resemblance between them. Geographical botany tells of their distribution on the earth's surface, and strives to account for the facts observed, while palaeobotany bears the same relation to distribution in the successive geological strata which make up the earth's crust. Economic botany comprises the study of the products of the vegetable kingdom as regards their use to man.
The simplest plants are very minute, and can only be studied by use of the compound microscope. A little rain-water which has been standing some time when thus examined is found to contain a number of roundish green objects, each of which is an individual plant, consisting of one cell only, with an external limiting membrane or cell-wall of a substance known as cellulose, within which is granular, viscid protoplasm. The protoplasm is permeated by a green colouring matter, chlorophyll, and embedded in it is an oval, more solid-looking body, the nucleus. Protococcus, as this little plant is called, though so simple, is yet able, by virtue of the living protoplasm, to take up food from the water around it; to work that food up into more cellulose and protoplasm so as to increase in size; and, finally, to produce new individuals, more Protococci. If we imagine Protococcus to elongate considerably and be repeatedly divided across by cell-walls, we get a row or filament of cells, a very common form among the low orders of plants: the masses of green threads seen floating in ditches in the spring and summer consist of such a filamentous plant called Spirogyra. Or we may have a single flat sheet of cells, as in the delicate green sea-weed Viva. Increased complexity of structure is exemplified in many of the ordinary sea-weeds, the stalk and more or less flattened expansions of which are several to many cells thick, the external cell-layers differing somewhat in structure from the internal. But we cannot distinguish in any of these between a stem, leaf, or root, as we can for instance in the more highly differentiated fern. Plants in which such a distinction cannot be drawn are called Thallophytes, and their whole body a thallus.
Thallophytes can be divided into two classes: Algae and Fungi. The former are distinguished by the presence of the green colouring matter chlorophyll, which is of vital importance in the physiology of the plant; sometimes the green colour is obscured by the presence of a brown or red compound, as in the brown and red sea-weeds. The Fungi contain no chlorophyll, and also differ in being composed not of expansions or masses of cells like the algae, but of numbers of delicate interlacing tubes or hyphae, often forming, as in the mushroom, quite large and complicated structures.
Lichens are an interesting class between Algae and Fungi, in as much as they are built up of an alga and a fungus, which live together and are mutually dependent on each other. Going a step higher we reach the Mosses, where, for the first time, we distinguish a clear differentiation of the part of the plant above ground into a stem and leaves borne upon it. The stem is attached to the soil by delicate colourless hairs - known as root-hairs. Its structure is, however, very simple, and the leaves are merely thin plates of cells. Rising still higher to the fern-like plants, including Equisetums (Horse-tails) and Lycopods (Club-mosses), we notice a great advance in complexity both of external form and internal structure. The leaves are large, often much branched, the stem stout and firm, while instead of the few simple hairs which was all the indication of a root-system to be found in the moss, there are well-developed true roots. Microscopic examination of sections of stem, leaf, or root, shows great differences in structure between various groups of cells; there is, in fact, marked differentiation of tissues. A tissue is a layer, row, or group of cells which have all undergone a similar development; by differentiation of tissues we mean that various layers, rows, or groups have developed in different ways, so that we can make out and mark by distinctive names the elements of which a stem or leaf is built up.
The structure of thallophytes and mosses is very simple, but in the ferns, besides other well-marked tissues, we meet with one of so great importance in the higher plants, and so constantly present, that it is used as a distinctive characteristic of all the plants above the mosses. Ferns and flowering-plants which contain this vascular tissue are known as vascular plants, in contrast to the thallophytes and mosses, or cellular plants, where it is not found. Microscopical examination of a very thin longitudinal slice of the stem, root, or leaf-stalk of a vascular plant shows bundles of long cells running lengthwise, the walls of which are not uniformly thin, as in the cells making up the groundwork of the portion examined, but are covered with curious markings which are seen ; to represent local thickenings of the walls, thin places, or pits, being left between them. These cells, which are quite empty, are the wood-cells; they are placed end to end, and when, as frequently occurs, the end-walls separating the cavities of two cells become absorbed, a wood vessel is formed. Near the elements of the wood, but differing greatly from them in their delicate unchanged walls and thick viscid contents, are the bast-vessels, or sieve-tubes, so called from the end-to-end communication between two cells being established, not by absorption of the whole wall, but by its perforation at numerous spots forming a sieve arrangement. This combination of wood and bast vessels forms the essential part of what is therefore known as vascular tissue.
Phanerogams, or Flowering-plants, represent the highest group of plants; Seed-plants would be a better name, as their main distinction from those already described is the production of a seed. The much greater variety in form and structure seen in them as compared with the ferns justifies us in regarding them as the highest group in the vegetable kingdom. They are divided into two classes. (1) Those in which the seed is developed on an open leaf, termed a carpel, and called therefore Gymnosperms; and (2) those in which the seed is developed in a closed chamber, formed by the folding together of one or more carpels, and called accordingly Angiosperms. To the former belong the Conifers - pines and firs - and Cycads; to the latter the rest of our trees and the enormous number of field and garden plants which are not ferns or mosses.
Angiosperms again are subdivided into Monocotyledons, where the embryo or young plant contained in the seed has only one primary leaf; and Dicotyledons, where an opposite pair of such leaves is present. Like the last group, Phanerogams are differentiated into a shoot-portion above the ground, consisting of a stem bearing leaves, and a subterranean root-portion. Both stem and root are often copiously branched, so that one individual may cover a large area both above and below ground. Stem, leaves, and roots all show great variety in form and adaptation.
The embryo, or rudimentary plant contained in the seed, consists of a very short axis or stem, bearing one (in Monocotyledons), two (in Dicotyledons), or several (in many Gymnosperms) primary leaves, the cotyledons, above which it terminates in a little bud or plumule, while below them the axis passes into the primary root or radicle. When the seed germinates the radicle is the first to protrude between the separating seed-coats, and growing downwards fixes itself in the aoil. Then the plumule grows out accompanied or not, as the case may be, by the cotyledons, which have hitherto concealed and protected it, and by rapid growth soon develops into a stem bearing leaves. The stem continues growing in length at its apex throughout the life of the plant; at a short distance below the apex growth in length ceases; but while in Gymnosperms and Dicotyledons it also continually increases in thickness through its whole length,
Monocotyledons are distinguished by the fact that when once the stem has been formed its diameter remains unchanged. The same rule applies to the branches. The cause of this difference is found in the internal structure. In the Gymnosperm and Dicotyledon a transverse section in a very young stage has the following appearance: Starting from the outside we have, (1) a single protective layer of cells with thick external walls, the epidermis. (2) Inside this, and forming what is called the cortex, are a number of thin-walled cells arranged like bricks in a wall, or touching only at their rounded edges, and leaving intercellular spaces. Such an arrangement, where there is no dove-tailing between the cells, is called parenchymatous. (3) Within the cortex a ring of vascular bundles, each consisting essentially of a little group of bast-vessels towards the outside and wood-Vessels on the inside, separated by a single layer of cells, the cambium-layer. (4) Within the ring of bundles the pith, of parenchyma like the cortex, and united to it by strands of similar parenchymatous cells passing between the bundles and known as medullary rays. As the young stem grows, however, the spaces between the bundles are filled up by development of fresh bast, cambium, and wood, so that instead of a number of separate bundles there is a complete vascular ring.
The cambium-ring remains in active growth throughout the whole life of the plant, and by producing new bast on the outside and wood on the inside causes continual increase in thickness. The epidermis, which would of course soon give way beneath the strain of the growth inside, is replaced as a protective layer by the bark, development of which keeps pace with increase in diameter. Now in the young monocotyledonous stem, instead of a few bundles arranged in a ring separating pith from cortex, a great number are scattered through the whole internal parenchymatous tissue, so that we cannot distinguish any pith at all. The bundles, moreover, have no cambium-layer, so that when once formed their development is complete, and there is no increase in thickness.
Stems, which may be simple or branched, are either aerial or subterranean. Aerial forms are, (1) erect, as the trunks of trees, or the more slender stems of most herbaceous plants, or the hollow culms of grasses. (2) Prostrate, as the creeping runners of the strawberry; or, (3) Climbing, in which case they may either twine round a support, like the hop; or hold on by means of prickles, like the bramble; or more usually by tendrils, as in the vine; or, finally, by root-fibres given off from the stem, as in the ivy. Examples of subterranean stems are, (1) the rhizome, a horizontal stem sending forth aerial shoots from its upper and roots from its lower surface; (2) the tuber, a much-swollen fleshy stem, like the potato, the eyes of which are buds; (3) the bulb, a very short undeveloped stem with crowded overlapping leaves, as the onion.
Branches proceed from buds which are formed in the autumn in the axils of the leaves, that is, at the point where the leaf or leaf-stalk is joined on to the stem; they remain dormant through the winter, and grow out into new shoots in the spring.
The leaf is borne on the stem; its tissues, epidermal, cortical, and vascular, are continuous with those of the stem; but it is distinguished by the fact that its growth is limited, it soon reaches the normal size and stops growing. The places where leaves come off from the stem are called nodes. There is great variety both in the position and form of leaves. Their position is said to be radical when they are all borne close together at the base of the stem, as in the dandelion; or cauline, when they are borne on the upper parts; in the latter case they may have a whorled arrangement, where several come off at the same level in a circle round the stem, as in the herb Paris; or opposite, where two stand on opposite sides at each node, as in the gentians; or alternate, where only one comes off at the same level. The study of leaf arrangement is known as phyllotaxy. A leaf may be stalked or sessile; if sessile, the blade is joined directly on to the stem. The stalk is known as the petiole, the flattened expanded blade as the lamina. The leaf may be simple or compound. A simple leaf cannot be divided without tearing the lamina; while a compound leaf is made up of independent leaflets, which may all come off from the same point as in the horse-chestnut, which is the digitate form; or may be arranged along a continuation of the petiole, as in the ash, which is the pinnate form of a compound leaf. The tissue of the lamina is traversed by vascular bundles, which are continuous through the petiole with those of the stem. The infinite variety of their ramifications is the cause of the often very characteristic venation of the leaves.
Leaves are said to be deciduous when they fall annually, as they do in the most common forest-trees; or persistent when they last longer, as in the firs, laurels, etc. Leaves of phanerogams are often very much modified or metamorphosed; thus the spines of the cactus are metamorphosed or modified leaves, as are also several forms of those curious leaf-growths known as pitchers, and many tendrils, such as those of the pea tribe. When we consider the flower we shall find that its various members are all more or less modified leaves.
In Dicotyledons and Gymnosperms the primary root or radicle after emerging from the seed continues to grow vigorously, often with copious lateral branching, forming an extensive root-system; but in Monocotyledons it soon perishes, and its place is taken by roots developed from the base of the stem, such roots are called adventitious.
Adventitious roots occur also in Dicotyledons, as in creeping stems like the strawberry, which bears buds at intervals from which new shoots are formed and roots given off. The clinging roots of the ivy are also adventitious. There are many forms of roots: some are large and woody, as those of trees; others fibrous, as in grasses; or they may be greatly swollen, forming the fleshy globose root of the turnip, or the conical one of the carrot. Such fleshy developments are due to the plant storing up a quantity of reserve food-material in the first year on which to draw in the second, when it will want to expend all its energy in flowering and fruiting. The potato, which is a swollen stem, answers the same purpose. The mistletoe and other parasites give off sucker-like roots which penetrate into the tissues of their host.
As to their reproduction, plants may be asexual, that is, not requiring the co-operation of two distinct (male and female) elements to produce a new individual; or sexual, when two such elements are necessary, and a process of fertilization takes place in which the female cell is impregnated by one or more male cells, and the cell resulting from the fusion of the two gives rise by very extensive growth and division to a new individual. In the very lowest plants, like Protococcus, only asexual reproduction is known, but in most Thallophytes both forms occur. In the asexual method numbers of small cells called spores are produced which on germination give rise to a plant similar to that which bore them. In the sexual process the contents of a male organ escape and impregnate the oosphere, or female cell contained in the female organ. The fertilized oosphere is termed an oospore, and by growth and division gives rise to a plant like that on which it was produced. In mosses and fern-like plants both sexual and asexual reproduction occur; but here the history of the life of the plant is divided into two stages, one in which it exists as an asexual individual, another in which it is sexual. In the fern, for instance, brown marks are seen on the back of some of the leaves, these are little cases containing spores; the fern as we know it is an asexual individual producing spores. The spores when set free germinate on a damp surface and produce not a new fern-plant, but a tiny green heart-shaped cellular expansion, called a prothallium, attached to the substratum by delicate root-hairs. Microscopical examination of its under surface reveals the sexual organs, a male organ producing motile male cells, which escape, pass into the female organ, and fertilize the oosphere, which then becomes the oospore. The oospore does not produce a new prothallium, but a fern-plant like the one with which we originally started. The cycle is thus complete.
The flower of a seed-plant is a shoot modified for purposes of reproduction. A buttercup, for instance, consists of a number of modified leaves borne in several whorls on the somewhat expanded top of the stalk, the receptacle or thalamus. Dissection of the flower shows (1) An outer whorl of five green leaves, very like ordinary foliage leaves; these are the sepals, and together make up the calyx. (2) An inner whorl of five yellow leaves, composing the corolla, each leaf being a petal. (3) More or less protected by the petals are a great number of stamens, each consisting of a slender stalk or filament capped by an anther, a little case containing the dry powdery pollen. The stamens are really much modified leaves collectively they form the andrcecium. (4) The rest of the receptacle right up to the apex is also covered by very much modified leaves, the carpels, forming the pistil or gynoecium. Each carpel consists of a basal portion, the ovary, in which is contained an ovule, and of a terminal beak-like portion, the style.
The androecium and gynoecium, being the parts directly concerned in reproduction, are distinguished, as the essential organs of the flower, from the calyx and corolla, which are only indirectly so concerned, though of great importance in the process. The ovule contained in the ovary is equivalent to the spore produced by the fern, but instead of escaping and producing an independent sexual individual it remains in the ovary, where processes go on within it corresponding to those resulting in the formation of the free and independent prothallium of the fern, and finally an oosphere is produced. Pollen from the stamen of the same or another plant has meanwhile been brought on to the special receptive portion of the style known as the stigma, where it protrudes a long tube which reaches right down through the style to the ovule. This tube represents the male element; it comes into close contact with the oosphere and fertilizes it. The oosphere then becomes an oospore, which by growth and division forms the embryo or new plant, while still included in the coats of the ovule. The ovule thus be comes the seed, which ultimately leaves the mother plant, bearing with it the embryo.
In the buttercup the members of each whorl of leaves composing the flower spring from the receptacle quite independently of each other, and of those of adjoining whorls. In many flowers, however, cohesion takes place between the similar members of a whorl; thus the petals frequently cohere to a greater or less distance from their base, and two great divisions of the Dicotyledons depend on this condition, namely, Polypetaloe, where the petals are free, as in the buttercup and poppy; and Gamopetaloe, with more or less coherent petals, as in the bluebell and primrose. Similarly the gynoecium, instead of being composed of free carpels as in the buttercup, the apocarpous condition, may be formed by the cohesion of several carpels into a one to several chambered compound ovary, as in the snapdragon, when it is said to be syncarpous. Adhesion also occurs between members of different whorls; thus the stamens are frequently inserted on the base of the petals, so that if we pull off a petal a stamen comes with it; and sometimes, as in orchids, the androecium and gynoecium are adherent. If the other floral whorls are inserted on the receptacle beneath the pistil they are said to be hypogynous and the pistil superior, as for instance in the poppy; if, on the other hand, as in the fuchsia, they spring from the top of the ovary, they are said to be epigynous and the pistil inferior.
An important characteristic is the fruit, which is the result of fertilization on the ovary. While the changes are going on by which the ovule becomes the seed the ovary also grows, often enormously, and forms the pericarp, which surrounds and protects the seed or seeds. The pericarp consists of an outer layer or epicarp, a middle layer or mesocarp, and an inner or endocarp. The outer usually forms the skin of the fruit; the two others may be succulent as in the berry, or the mesocarp only may be succulent and the endocarp hard and stony as in the plum. Besides the embryo the seed contains a store of food-material on which the young plant feeds during tlie first stages of its growth. This consists of albuminous, starchy, or fatty matter. In what are called albuminous seeds, as those of palms, the seed is chiefly composed of food-material in which is embedded a small embryo; the edible part of a cocoa-nut is the albuminous reserve material. In other seeds, like the bean, the fleshy cotyledons have already absorbed this food material into themselves, and the seedling draws on its own cotyledons for support; these seeds are known as exalbuminous.
It was stated above that the ovule might be fertilized by pollen from the same flower or from another plant; experiment has shown that the latter produces better results, both as regards quality and quantity of seed, and the vigour of the seedlings. That is, cross-fertilization is preferable to self-fertilization, and the various, often extremely curious, shapes of a flower and its parts are mainly for the purpose of ensuring the former and preventing the latter.
Many flowers contain both stamens and pistil, these are termed bisexual or hermaphrodite; while others contain stamens or pistil only, such are said to be unisexual. When both male and female flowers occur on the same plant the species is monoecious, like the hazel; while it is dioecious if the separate sexes are borne on different individuals, as is the case in the hop.
Plants which, like the sunflower, pass through all the stages from germination to production of fruit and seed in one season, and then perish, are called annuals; if two years are required, as with the turnip and onion, they are biennials; while perennials last several to many years, during which they may flower and seed many times.
A plant is built up chiefly of four elements: carbon, hydrogen, oxygen, and nitrogen, with small quantities of sulphur and phosphorus and some mineral matter. Substances containing these must therefore form the food. A green plant can take up its carbonaceous food in a very simple form by means of the green chlorophyll contained especially in its leaves. This absorbs some of the sun's rays, and by virtue of the energy represented by the light so absorbed it can obtain the carbon from the carbon dioxide gas present in the atmosphere. An animal, having no chlorophyll, has to use more complex carbon-containing compounds, in fact those which have already been worked up in the vegetable kingdom. The other items of the food are obtained from the water and mineral salts in the soil, the salts being brought into solution and absorbed with large quantities of water by the roots. The leaves are the laboratory where the food is worked up into the complex compounds which form the plant substance, and to raise the crude material from the absorbing roots to the leaves there is an upward current of liquid through the stem. This is known as the transpiration current; it travels in the wood-cells. A much larger quantity of water is absorbed than is required as food; this is got rid of by transpiration, that is, by the giving off of water-vapour from the leaves. This is evident if a plant be placed under a glass shade in the sunlight, the vapour given off becoming condensed on the glass. The complex compounds elaborated in the leaves are returned to all parts of the plant where growth, or storage of reserve-material, is taking place, by means of the other constituent of the vascular bundle, the basttissue.
Fungi and a few seed-plants contain no chlorophyll and cannot therefore get their carbonaceous food from the carbon dioxide gas of the atmosphere, but have to live on decaying vegetable or animal matter, when they are termed saprophytes, like mushrooms, or on living plants or animals, when they are parasites; such are the fungi which cause diseases in these organisms. Plants, like animals, breathe; respiration goes on both day and night, and is represented by the absorption of oxygen from, and the return of carbon dioxide gas to the atmosphere. If we prevent a plant from breathing, that is keep it in an atmosphere containing no free oxygen, it will sooner or later die.
In botany, as in zoology, individuals which closely resemble each other form collectively a species. Where existing differences are considered too minute to constitute difference of species the set of individuals in which they occur ranks as a variety of the species. Species which, though having each some distinctive peculiarity, yet on the whole resemble each other, constitute a genus. Assemblages of genera agreeing in certain marked characters form families or natural orders. The names of the orders are generally formed on the type of Rosaceae, the rose order, Ulmaceae, the elm order, etc. Classes, such as Monocotyledons and Dicotyledons, contain a large number of natural orders. The older systems of classification were based largely on the uses of plants, for they were studied simply from a medicinal or generally economic point of view.
In 1682, however, John Ray discovered the difference between Monocotyledons and Dicotyledons, and published an arrangement of plants founded on their structural forms, especially on the characters afforded by the seed; this formed the basis of the natural system of classification, one, that is, which brings together those genera and families which a careful comparative study of the whole structure and development shows to be most nearly related.
Linnaeus did not recognize John Ray's great primary divisions, and his system from 1735 is a purely artificial one, since it only takes account of a few marked characters afforded by one or two sets of organs, and does not propose to unite plants by their natural affinities. He divides Phanerogams into twenty-three classes, chiefly according to the number and character of the stamens; each class is subdivided into orders based on the number and character of the styles. Owing to the exclusive part played by the sexual organs this arrangement is known as the sexual system.
The great value of Linnaeus's work was his careful scientific revision and adjustment of all the known genera, and his introduction of the binomial system of nomenclature, in which every species has a double name, that of the genus to which it belongs coming first, then that of the species; thus Bellis perennis L. is the daisy, and the name shows that the species perennis of the genus Bellis is the plant in question. The L. which follows indicates that we mean the plant so named by Linnceus. The sexual system is now only of historic interest. By the sagacity of the Jussieus the genera of Linnaeus were more or less naturally grouped under John Ray's primary divisions; and by the subsequent labours of De Candolle, Robert Brown, Lindley, and many others we have attained to a fairly natural system. Research Botany
Bow Compasses are compasses having the two legs united by a bow passing through one of them, the distance between the legs being adjusted by means of a screw and nut. Research Bow Compasses
Bowstring-hemp is a fibre extracted from the leaves of the Indian plant Sanseviera zeylanica. It is so named because the natives used it to make bow-strings. Research Bowstring-Hemp
Boxer 99 is a powerful, full-featured text editor for the Windows operating system that will appeal to programmers, writers, engineers, students and others. Boxer features colour syntax highlighting and printing, column blocking, undo and redo, regular expression searches and other features. Research Boxer 99
Boyle's Law (also known as Mariotte's Law) is a law in physics to the effect that the volume of a gas will vary inversely with the pressure to which it is subjected if its temperature is kept constant. Research Boyle's Law
Brachycephalic is a term applied in ethnology to heads whose diameter from side to side is not much less than from front to back, as in the Mongolian type: opposed to dolichocephalic. Research Brachycephalic
A brake is a contrivance for retarding or arresting motion by means of friction. In machinery it generally consists of a simple or compound lever, that may be pressed forcibly upon the periphery of a wheel, fixed upon a shaft or axis. A similar contrivance is attached to motor vehicles and railway carriages, but continuous brakes applied to every pair of wheels in a railway train, and operated by air either by the compression or vacuum method, are now generally used on railways. By the compression method, of which the Westinghouse brake is an example, the air is compressed by a pump on the locomotive and conveyed by pipes and tubes to cylinders which are under each car, and the pistons of which act on the brake-levers. In the vacuum method, exemplified in the Loughridge brake, the air is exhausted from the device beneath the car, and the pressure of the atmosphere operates the brake-levers. Research Brake
Brass is an alloy of copper and zinc formerly called Prince's Metal, German Gold, Deutsche Gold and also Dutch Gold. Brass is of a bright-yellow colour, and hard, ductile, and malleable. The best brass consists of two parts by weight of copper to one of zinc; but any degree of variation may be obtained by altering the proportions; thus by increasing the quantity of zinc we may form tombac and pinchbeck, and with nearly a seventh more of zinc than copper the compound becomes brittle and of a silver-white colour. By increasing the copper, on the other hand, the compound increases in strength and tenacity. Brass which is to be turned or filed is made workable by mixing about 2 percent of lead in the alloy, which has the effect of hardening the brass and preventing the tool being clogged. For engraving purposes a little tin is usually mixed with the brass. Brass is used for a vast variety of purposes, both useful and ornamental. Research Brass
Brazing is a form of soldering by means of a kind of brass called spelter. The surfaces to be united are thoroughly cleaned, and heated by a forge or blow-torch, spelter is then applied to the joint in the form of a wire or filings along with borax which acts as a flux. Research Brazing
A breast-wheel is a water-wheel in which the water driving it is delivered to the float-boards between the top and bottom, generally a little below the level of the axis. In this kind of wheel the water acts partly by impulse, partly by weight. Research Breast-Wheel
Breeding is the art of improving races or breeds of domestic animals, or modifying them in certain directions, by continuous attention to their pairing, in conjunction with a similar attention to their feeding and general treatment.
Animals (and plants no less) show great susceptibility of modification under systematic cultivation; and there can be no doubt that by such cultivation the sum of desirable qualities in particular races has been greatly increased, and that in two ways. Individual specimens are produced possessing more good qualities than can be found in any one specimen of the original stock; and from the same stock many varieties are taken characterized by different perfections, the germs of all of which may have been in the original stock but could not have been simultaneously developed in a single specimen. But when an effort is made to develop rapidly, or to its extreme limit, any particular quality, it is always made at the expense of some other quality, or of other qualities generally, by which the intrinsic value of the result is necessarily affected. High speed in horses, for example, is only attained at the expense of a sacrifice of strength and power of endurance.
So the celebrated merinosheep are the result of a system of breeding which reduces the general size and vigour of the animal, and diminishes the value of the carcass. Much care and judgment, therefore, are needed in breeding, not only in order to produce a particular effect, but also to produce it with the least sacrifice of other qualities.
Breeding, as a means of improving domestic animals, has been practised more or less systematically wherever any attention has been paid to the care of live stock, and nowhere have more satisfactory results been obtained than in Britain. One of the earliest improvers in Britain was Robert Bakewell, of Dishley, in Leicestershire, who commenced his experiments about 1745, and was very successful, especially with sheep, the celebrated Dishley breed of Leicestershiresheep having since maintained a high reputation. Quantity of meat, smallness of bone, lightness of offal; in cows, yield and quality of milk, in sheep, weight of fleece and fineness of wool, have all been studied with remarkable effects by modern breeders. Research Breeding
In telecommunications, BRI (Basic Rate Interface) is a consumer grade ISDN line consisting of 2 64K bearer channels and one 16K delta (controller) channel. Research BRI
BRIEF by Solution Systems Inc. is a highly flexible, full-screen editor and macro generator designed for use with dBase or high-level languages such as C, Pascal, and COBOL. You can customise the editor by reconfiguring your keyboard, changing the command functions, and creating new commands as needed. BRIEF for OS/2 runs in OS/ 2 protected mode to take advantage of that platform's multitasking and virtual memory support. It is fully compatible with the DOS version of BRIEF. The
BRIEF macro language is a structured programming language similar to C. The macro language can be programmed and must be compiled to run the commands you create. BRIEF has unlimited variables and an IF/THEN/ ELSE loop feature found only in high-level on-screen languages.
BRIEF lets you undo your last 300 commands including deletions, insertions, cursor movement, cut and paste, global replacement, and read of file. There is no limit to file size, the number of active files, or the number of windows on-screen. Research Brief
Brine is water saturated with common salt. It is naturally produced in many places beneath the surface of the earth, and is also made artificially, for preserving meat, a little potassium nitrate (saltpetre) being generally added to the solution. Research Brine
A briquette is a mass of fuel in the shape of a brick, or a small ovoid, consisting mainly of coal-dust and some binding material, such as pitch, tar or asphalt. The materials are pressed together, heated and then pressed in moulds. Briquettes are useful as a domestic fuel as they burn slowly, but have the drawback of not producing as much heat as good coal and leaving a lot of ash. Research Briquette
The Britannia joint is a form of electrical joint used for bare overhead wires where great tensile strength is required. The two wires are each tinned, and then each have a short shoulder bent in them, and are then bound together with tinned wire before the whole is soldered. Research Britannia Joint
Britannia Metal (White Metal) is a metallic alloy consisting of 85 to 94 percent tin, 5 to 10 percent antimony and about one percent of zinc or bismuth. It was used before cupro-nickel for making teapots and cutlery. Research Britannia Metal
Broadband is a generic term for non-dial-up modem internet access. The term confusingly includes aDSL, DSL and cable connections. Broadband connections are often asynchronous - the rate of sending data is not the same as the rate at which data is received - and sometimes suffer from 'contention' where multiple subscribers share a physical connection, the available data transfer being shared equally between the connected users. Contention occurs throughout the Internet, but can be particularly noticeable on DSL type broadband connections where additional contention occurs closer to the user. Research Broadband
A broadcast storm is a form of malicious denial of service attack launched against a computer network. There are various forms of a broadcast storm, but the basic method is to send a lot of data packets to all the hosts in the network with a destination address that don't exist. Each host will try to forward each packet, which then returns because of the invalid destination address, and with enough data packets doing this the network can become swamped and be unable to cope with the legitimate traffic. Research Broadcast Storm
Bromine (named from the Greek bromos meaning a getid odour) is a non-metallic element normally a deep red, corrosive, toxic liquid giving of an irritating reddish brown vapour of disagreeable odour. It has the symbolBr. It was first discovered in salt water by Balard in 1826.
In its general chemical properties it much resembles chlorine and iodine, and is generally associated with them. As bromides it is found in minute quantities in sea-water, in the ashes of marine plants, in animals, and in some salt springs. It may be extracted from bittern by the agency of chlorine. It has bleaching powers like chlorine, and is very poisonous. Its density is about three times that of water. It combines with hydrogen to form hydrobromic acid gas. With oxygen and hydrogen it forms bromic acid. Bromide of potassium (K Br) has sedative and other properties, and is used in medicine (for treating scrofula, goitre, rheumatism, &c.); bromide of silver is used in film photography. Research Bromine
Bromoform is the bromineanalogue of chloroform. It is a very heavy liquid, which is insoluble in water and turns red in the light from the separation of bromine. It is used for separating and determining the density of minerals. Research Bromoform
Bronopol is a toxicalcohol used in fabric softeners and detergents. It is also used in face creams, shampoos, hair dressings, mascara and bath oils. It is a white crystalline powder that can cause skin irritation at concentrations of .25%. Research Bronopol
A brontometer is an apparatus for measuring thunderstorms invented by Richard, of Paris in 1890. The recording part of the instrument consisted of a drum about 20 cm wide on which was coiled endless paper fed by a clock which caused the paper to travel at a rate of 1 cm per minute. Pressing on the paper were several pens connected to various automatic meteorological apparatus. The pens registered the velocity of the wind, rainfall and atmospheric pressure. Other pens worked by keys enabled the observer to record the precise time of thunder and lightning. Research Brontometer
Bronze is an alloy of copper, to which other metallic substances are sometimes added, especially zinc. It is a finegrained metal, taking a smooth and polished surface, harder and more fusible than copper, but not so malleable. In various parts of the world weapons and implements were made of this alloy before iron came into use, and hence the bronze age is regarded as one coming between the stone age and the iron age of prehistoric archeology.
Both in ancient and modern times bronze has been much used in making casts of all kinds, medals, bas-reliefs, statues, and other works of art; and varieties of it are also used for bells, gongs, reflectors of telescopes, and formerly for cannons, etc.
Bronze is of a reddish, brownish, or olive-green colour, and is darkened by exposure to the atmosphere. Ancient bronze generally contains from 4 to 15 percent of tin. The alloy of British bronze coinage at the start of the 20th century consisted of 94 parts of copper, 4 of tin, and 1 of zinc. An alloy of about 85 parts copper, 11 zinc, and 4 tin is used for statues. Bell-metal consists of 78 of copper and 22 of tin. An alloy called phosphor bronze, consisting of about 90 percent of copper, 9 of tin, and from .5 to .75 of phosphorus has been found to have peculiar advantages for certain purposes. The addition of phosphorus increases the homogeneousness of the compound, and by varying the proportion of the constituents the hardness, tenacity, and elasticity of the alloy may be modified at pleasure. Research Bronze
Bronzing is the operation of covering articles with a wash or coating to give them the appearance of bronze. Two kinds are common, the yellow and the red. The yellow is made of fine copper dust, the red of copper dust with a little pulverized red ochre. The fine green tint which bronze acquires by oxidization, called patina antiqua, is imitated by an application of sal-ammoniac and salt of sorrel dissolved in vinegar. Towards the end of the 19th century bronze was deposited on small statues and other articles with good effect by means of the electrotype process. Research Bronzing
In computing, Brooks's Law states 'Adding manpower to a late software project makes it later'. A result of the fact that the advantage from splitting work among N programmers is O(N) (that is, proportional to N), but the complexity and communications cost associated with co-ordinating and then merging their work is O(N^2) (that is, proportional to the square of N). The quote is from Fred Brooks, a manager of IBM's OS/360 project and author of 'The Mythical Man-Month'. Research Brook's Law
In chemistry, Brownian movement is the rapid oscillatory movement of small particles when suspended in water or other liquids. Research Brownian movement
A browser, or more properly a web browser, is a computer program used to render and display HTML documents. Web browsers are typically graphical and based upon an early design known as Mosaic, invented by staff at the NCSA. Web browsers are also becoming available built into other devices, such as mobile phones. Research Browser
A browser sniffer is a script, usually a JavaScript, embedded in an HTML web page which attempts to determine the client web browser being used to access the page. A browser sniffer attempts to read the USER AGENT parameter passed by the clientbrowser, and may redirect the reader automatically to different web pages depending upon the perceived browser in use. Browser sniffers are used because of incompatibilities in the enhanced functionality offered by different web browsers, and the desire of web page designers to achieve a consistent look-and-feel to their web pages across different platforms. Research Browser Sniffer
Brunswick Black is a hard, quick drying bituminous varnish or pigment composed of asphalt or pitch, linseed oil and turpentine used to give a glossy appearance to metal and other articles. Brunswick Black has a fair degree of heat resistance and was formerly used for stoves. Research Brunswick Black
In computing, a bubble sort is a technique for sorting data in which adjacent items are continually exchanged until the data is in sequence. It is so named because elements appear to 'bubble' up the list. Research Bubble sort
A buck saw is a type of saw with its blade set in a frame and tensioned by a turnbuckle across the back of the frame. Buck saws are used for cutting wood. Research Buck Saw
In chemistry, a buffer is a substance that keeps the pH of a solution relatively constant in spite of the addition of considerable amounts of acid or base. Research Buffer
In audio engineering a bulk dump is a MIDIfunction that allow the transfer of system specific data, such as sample files or mixer settings, between MIDI capable devices. The data are transmitted as MIDI System Exclusive messages. Research Bulk Dump
A Bunsen burner is a small gas and air burner used chiefly in chemistry laboratories to heat substances. In the standard model, a Bunsen burner has an air regulator consisting of large holes on two sides of the vertical shaft which may be opened or closed by means of a metal collar. Research Bunsen Burner
A Bunsen's battery is a form of galvanic battery, the cells of which consist of cleft cylinders of zinc immersed in dilute sulphuric acid, and rectangular prisms of carbon in nitric acid, with an intervening porous cell of unglazed earthenware. Research Bunsen's Battery
A burin (also called a graver) is a tempered steel instrument used for engravingcopper, steel etc. It has a triangular point attached to a wooden handle. In working, the burin is held in the palm of the hand, and pushed forward so as to cut a portion of the metal. Research Burin
Burnett's Disinfecting Liquid is an antiseptic liquid and deodorizer prepared from chloride of zinc. It was useful in deodorizing sewage, bilge-water in ships, etc, and was found in service in the dissecting-room during the 19th century and early 20th century. Research Burnett's Disinfecting Liquid
A burning-glass is a lens which, by bringing the sun's rays rapidly to a focus, produces a heat strong enough to kindle combustible matter.
The lenses commonly used were convex on both sides, and having a small focal distance. That such a glass may produce its greatest effect it is necessary that the rays of the sun should fall upon it in a perpendicular direction. The effect may be greatly augmented by the use of a second lens, of a smaller focal distance, placed between the first and its focus. Some immense burning-glasses have been made, producing surprising effects.
Concave burning-mirrors produce the same kind of results, and have almost four times more power than burning-glasses of equal extent and curvature. The concavity must present a surface of high reflecting power (polished silver or other metal, or silvered glass), and must be either spherical or parabolic. Plane mirrors may also be employed like concave ones, if several of them are combined in a proper manner.
The ancients were acquainted with such mirrors, and Archimedes is said to have set the Roman fleet on fire at the siege of Syracuse (B.C. 212) by some such means (effectively the first use of the 'ray-gun' of science fiction). In 1747 Buffon by a combination of mirrors burned wood at the distance of 200 feet (60 metres) and melted tin at the distance of 150 (45 metres), etc. Research Burning-Glass
A burnisher is a blunt, smooth tool used for polishing rough surfaces by rubbing. Agate, tempered steel and dogs' teeth are traditionally used to make burnishes. Research Burnisher
Burnt Sienna is the popular name for Terradi Sienna, a brown ferruginousochre used in painting, and obtained from Italy. Before being used as a pigment it is calcined, and hence the name
Burnt Sienna. Research Burnt Sienna
Two clack valves, set back to back constitute a butterfly valve. The disk valve of rubber, plastic, vulcanised fibre, or metal moves axially on a fixed central spindle, its travel being limited by a perforated guard. If a flexible material be used for the disk the seating is usually a grid. Valves of this kind are the best for air- and water-pumps of large capacity working against moderate pressures. Research Butterfly Valve
Butyric Acid is an acid originally obtained from butter, and also present in perspiration. It is a colourless liquid, having a smell like that of rancid butter, and the formula C4H3O2. Research Butyric Acid
Butyric Ether is a substance obtained from butyric acid with the flavour of pineapples, and traditionally used in the flavouring of confectionery and as an ingredient in perfumes, etc. Research Butyric Ether
Byline by Ashton-Tate offers a style of desktop publishing for people who don't like or don't have a mouse. Not quite a WYSIWYGpackage nor a fully-fledged batch program, Byline uses a page layout system with keyboard-only interaction and instant preview. Byline uses familiar commands and keyboard sequences to lay out a page, complete with multiple columns and graphics. It can be used to integrate text and graphics from many sources including standard word processing and paint programs, dBase users can read data directly from their database and format it with Byline. Grids are used to set up pages and help create an organised document. One side of the screen displays the document while the other side contains a form which allows definition of document characteristics such as titles, borders and font style and sizes. Nearly all formatting is maintained when files are imported. Byline can edit the text with its built-in word processor which includes cut-and-paste and search-and-replace functions. Changes made to word processing documents in
Byline are reflected in the original file. Four fonts are provided. Times, Helvetica, Courier and dBase. Other fonts and typeface sizes which are available in a given printer are inaccessible. Byline's graphic editing capabilities include cropping and scaling of images. All other editing must be done in the graphics package. Especially useful is the screen capture utility which allows any screen image to be saved if it is in a graphic file format Byline can read. A demonstration disk is available. This software is designed for minor publishing requirements giving simple, effective desktop publishing facilities and which are easy to learn but flexible enough to produce good handouts, memos and the occasional newsletters. Byline will produce documents which are more readable and impressive than ordinary typed documents but not to PageMaker or Ventura Publisher standard. Research Byline
In computing, a byte is eight consecutive binary units (bits) interpreted as a number between 0 and 255, unsigned, or between -128 and 127, signed. Research Byte
Abbreviations
SciTech
Research Babbage
