The G6-233 is a Personal Computer by Gateway 2000. It is built around an Intel 233Mhz Pentium II Processor with 64MB of SDRAM (expandable to 384MB), 512KB L2 Cache, 4.3GB, 10ms UltraATA Hard Drive, 1 3.5' 1.44MB Floppy Disk Drive, Mitsumi 32X 90ms CDROM, STBAGP 3D Graphics Accelerator with 4MB DRAM, and supplied with a 15 inch EV500 TCO-92 0.28dp Monitor. Research G6-233
Gadolinium is a silvery white metal element with the symbolGd of the group of rare earth metals. It is found in the mineral gadolinite. It is ferromagnetic (strongly attracted by a magnet). The metal is relatively stable in dry air, but in moist air it tarnishes with the formation of a loosely adhering oxide film which 'spalls' off and exposes more surface to oxidation. The metal reacts slowly with water and is soluble in dilute acid.
Gadolinium has the highest thermal neutron capture cross-section of any known element. Gadolinium is used for making gadolinium yttrium garnets which have microwave applications.
Gadolinium compounds are used for making phosphors for colour TV tubes. Gadolinium is also used in alloys and CD disks and has superconductive properties. Solutions of gadolinium compounds are used as intravenous contrasts to enhance images in patients undergoing MRI (magnetic resonance imaging). Research Gadolinium
A galactometer is an instrument, similar to a hydrometer, used for measuring the relative density of milk. It is used to determine the fat content. Research Galactometer
Galactose (lactoglucose) is a sugar formed together with glucose when lactose is boiled in dilute acids. It occurs naturally in ivy. Research Galactose
Galalith (erinoid) is a synthetic plastic material manufactured by the interaction of casein and formaldehyde. It is odourless, insoluble in water, and only with difficulty inflammable. Research Galalith
Galbanum is a bitter aromatic gumresin extracted from any of several Asian umbelliferous plants of the genusFerula, especially from Ferula galbaniflua. It is used in incense and in medicine as a counterirritant. Research Galbanum
Galipot, also known as French turpentine, is a resin obtained from several species of pine, especially from the south European tree Pinus pinaster. The resin solidies as long, soft stalactitic pieces down the sides of the tree by evaporation, of part of the volatile oil. Research Galipot
A galley was a rectangular tray, open at one end, used for holding set type in the printing industry. Later the term came to be a unit of measurement, 22 inches long, used in type composition. Research Galley
Gallic Acid (Trihydroxy-benzoic Acid) is an acid which was first procured from the gall-nut by Scheele in 1786. It occurs in the seeds of the mango, acorn, tea, walnut and many other plants and is a decomposition product of tannic acid. It crystallizes in brilliant colourless prisms, with an astringenttaste. It colours ferric salts of a deep bluish-black. It is used as an important black dye and is an ingredient in ink. Research Gallic Acid
Gallium is a rare malleable metal element, discovered by spectrumanalysis in 1875 by De Boisbaudran in the zinc-blende of Pierrefitte in the Pyrenees. It is of a greyish-white colour, has a brilliant lustre, and is fused by the mere warmth of the hand. In its properties it is related to aluminium. Research Gallium
The galvanic skin response (GSR) is a change in the electrical resistance of the skin occurring in moments of strong emotion. Measurements of this change are used in lie detector tests. Research Galvanic Skin Response
Galvanism is the production of electricity by means of the galvanic battery. The name is derived from Galvani, professor of anatomy at Bologna, who observed that the limbs of a dead frog could be caused to move by the contact of metals. His experiments attracted the attention of Volta, professor of natural philosophy at Pavia, who shortly afterwards invented the galvanic or voltaic battery. Research Galvanism
Galvanized Iron is a name loosely given to sheets of iron coated with zinc by a non-galvanic process, the iron being first cleansed by friction and the action of dilute sulphuric acid, and then plunged into a bath composed of melted zinc and other substances, as sal-ammoniac, or mercury and potassium; more properly the name is given to sheets of iron coated first with tin by a galvanic process, and then with zinc by immersion in a bath containing fluidzinc covered with sal-ammoniac mixed with earthy matter. So long as the coating is entire, and so long as it is not exposed to corrosive substances, galvanized iron is very durable. Galvanized iron has been used as a building material since at least 1905. Research Galvanized Iron
A galvanometer is an instrument for measuring a (usually minute) electric current by the deflection of a magnetic needle. Basically, it is comprised of a coil beneath a suspended magnetic needle. When electric current passes through the coil it sets up a magnetic field and attracts the needle, the stronger the current the more powerful the magnetic field and the more pronounced the needle's deflection from the earth's magnetic field. Research Galvanometer
Gamboge is a gum-resin obtained from a tree (Garcinia) growing in the Far East. It is used as a yellow paint-pigment, in the manufacture of varnish, in tanning and as a purgative. Research Gamboge
Gamma Rays are a short, intense burst of electromagnetic radiation emitted by an unstable nucleus of radioactive material. Gamma rays have no electrical charge and can penetrate even thick lead and concrete. Research Gamma Rays
Gas is an elastic aeriform fluid, a term originally synonymous with air, but afterwards restricted to such bodies as were supposed to be incapable of being reduced to a liquid or solid state. Under this supposition gas was a term applied to all permanently elastic fluids or airs differing from common air. After the liquefaction of gases by Faraday, the old distinction between gas and vapour, that the latter could be reduced to a liquid or solid condition by reduction of temperature and increase of pressure, while a gas could not be so altered, was no longer tenable, so that the term resumed nearly its original signification, and designates any substance in an elastic aeriform state.
Gases are distinguished from liquids by the name of elastic fluids; while liquids are termed non-elastic, because they have, comparatively, no elasticity. But the most promient distinction is the following: Liquids may be compressed to a slight extent, but when the pressure is released they return to their original condition, and in so far they are elastic; but gases when left unconfined expand in every direction. In respect of this expansiveness, all gaseous bodies obey more or less strictly two laws, commonly called the 'gaseous laws'.
The first, known as Boyle's Law, given first by Robert Boyle in 1662, and then by Mariotte in 1676, is that 'The volimie of a given mass of gas varies inversely with the pressure to which the gas is subjected'.
The second of the gaseous laws is that of Charles or Gay-Lussac. Dalton published it in 1801; but Gay-Lussac, who stated it in 1802, gives the credit of having discovered it, fifteen years previously, to Citizen Charles. The law may be stated as follows: 'The volume of a gas maintained under constant pressure increases for equal increments of temperature by a constant fraction of its original volume; and this fraction is the same whatever is the nature of the gas. A mass of gas, whose volume is 273 at 0 degrees C., becomes 274 at 1 degree, and 373 at 100 degrees, the pressure remaining constant'. This law may also be stated in the form - the volume of a given mass of any gas is directly proportional to the absolute temperature of the gas, provided the pressure remain constant. The absolute temperature is obtained by adding 273 degrees to the temperature in degrees centigrade, since the absolute zero is -273 degrees C.
In virtue of these laws a gas may now be defined to be a substance possessing the condition of perfect fluidelasticity, and presenting under a constant pressure a uniform state of expansion for equal increments of temperature - a property distinguishing it from vapour. There is, however, no known gas that obeys these two laws perfectly: thus, of the six gases oxygen, hydrogen, nitrogen, carbon monoxide, nitric oxide, and methane, all except hydrogen are more compressible than they should be theoretically, while hydrogen deviates slightly in the opposite direction, being less compressible than Boyle's law would indicate. The other gases exhibit even greater deviations from Boyle's law, and the amount of the deviation rapidly increases as the gas is brought nearer and nearer to liquefaction.
Charles' law, according to which equal rises in temperature should produce equal increments in volume, does not hold absolutely for all gases, and the deviations become greater as the point of liquefaction is approached. Characteristic of gases is the fact that they all possess a critical point or critical temperature, at which all distinction between the liquid and gaseous phases disappear wlien a suitable pressure (the critical pressure) is used. This was first observed by Andrews for carbon dioxide, the critical temperature of which is 31.3 degrees C, and its critical pressure 72.9 atmospheres. The liquefaction of gases is effected by the aid of low temperature and high pressure. Research Gas
Gas black is a finely powdered carbon produced by the incomplete burning of natural gas. It is used as a pigment in paints, where it provides an intense black colour with good staining properties. Research Gas Black
Gas chromatography is a technique for analysing a mixture of volatile substances in which the mixture is carried by an inert gas through a column packed with a selective adsorbent and a detector records on a moving strip the conductivity of the gas leaving the tube. Peaks on the resulting graph indicate the presence of a particular component. Research Gas Chromatography
Gas engine was the original name for the combustion engine - that is an engine in which the movement of the pistons is caused by the explosive energy of a mixture of inflammable gas with atmospheric air, the early gas being used being ordinary coal gas, gas specially made, gas from blast furnaces, the vapour of petroleum, etc.
One of the first successful and commercial gas engines was that of the German, Otto, introduced about 1866. In its early form it consists of an upright cylinder in which worked a heavy piston, the rod of which formed a rack gearing with a cogwheel on the shaft of the fly-wheel. As the piston ascended the cog-wheel slipped loosely on the shaft; as it descended its energy was transferred to the shaft through the cog-wheel, the force of the down-stroke being due to the rapid condensation of the gases after the explosion aided by the weight of the piston itself. The mixed gases - coal-gas and air - were introduced at the base of the cylinder and fired by communication with a gas-jet kept constantly burning. One great objection to this engine - its noise in working - was overcome in the Otto Silent Gas Engine, in which the working cylinder was horizontal and considerably shorter than in the older form. By 1906 various other forms of gas engine had also been introduced, some of them of a large size, up to 2000 horse-power. In these the compression of the gas before ignition was the rule, an improvement that Otto adopted in 1876, but much higher compression, was then employed than before, a great saving in gas being thus secured. By 1905 the Otto engine manufactured by Crossley was the best known, such engines being capable of performing the same work as any existing stationery engine. The Otto gas engine formed the basis of the internal-combustion engine (as it was later known) of the mid-20th century. Research Gas Engine
The gas equation is an equation that equates the product of the pressure and the volume of one mole of a gas to the product of its thermodynamic temperature and the gas constant. The equation is exact for an ideal gas and is a good approximation for real gases at low pressures. Research Gas Equation
Gas lighting was a formerly common application of ordinary coal-gas, the gas obtained by heating coal, to the lighting of buildings, streets, &c. In 1739 the Reverend Clayton published a paper in
the Philosophical Transactions, on the inflammable nature of the gases obtained by the decomposition of pit-coal in heated close vessels; but no practical application of thia discovery was made before 1792, when a Mr. Murdoch, a native of Ayrshire, in the employ of Messrs. Watt and Boulton, lighted his own house and offices at Redruth on this principle. In 1798 he erected a gas apparatus on a large scale at the SohoFoundry, Birmingham, and in 1802 Le Bon lighted his house in Paris by gas, and made a proposal to supply the whole city. In 1803 Mr. Winsor exhibited gas illuminations at London in the Lyceum, and afterwards raised the sum of 50,000 pounds from a number of subscribers who formed themselves into a National Light and Heat Company in 1810. With this money Mr. Winsor lighted Pall Mall, but was soon succeeded by Mr. Samuel Grieg, who invented the hydraulic main, the wet-lime purifier, and the wet gas-meter. From this time coal gas became the most common illuminating agent wherever it could be prepared economically.
Another kind of gas for lighting that came into use to some extent, namely, water-gas, was produced from the decomposition of water in the form of steam by passing it through incandescent fuel.
Gas was obtained from coal, the best sorts being those bituminous coals known in England by the name of cannel, and in Scotland by the name of parrot. The coal was distilled in retorts of cast-iron or later, after about 1900, more generally of fire-clay, heated to a bright red heat. As they issued from the retort into the hydraulic main the products of distillation contained vapours of tar, together with steam impregnated with more or less ammoniumcarbonate, sulphide, hydrosulphide, thiosulphite, etc. These vapours would condense in the pipes in which the gas must be distributed, and would clog them up; they therefore had to be so far removed by previous cooling as to cause no inconvenient condensation at ordinary temperatures. The crude gas contained besides, sulphuretted hydrogen, the combustion of which would cause an offensive smell. Carbonic acid weakened the illuminating power of the gas, and also had to be removed.
The profitable consumption of gas, whereby the strongest light can be had at the least expenditure of gas, depends considerably upon the form of the burner, and the mode by which the flame is fed with the air necessary for its combustion. There must be a sufficient supply of oxygen to convert the carbon of the gas into carbonic acid, and the hydrogen into water. If there is not a sufficient supply of oxygen, the flame will be smoky from excess of carbon. In this case the remedy is either to reduce the supply of gas or increase the supply of air. This may be effected by modifying the form of the burner, or in the case of the Argand burner by having a different shape of glass chimney. As to the form of the burner, it was found that a plain jet about 6 mm in diameter at the orifice, will not give a flame free from smoke of a greater height than 60 mm but the same quantity of gas which would give a smoky flame from a plain jet, would produce a clear bright flame by extending or dividing the aperture of the jet so as to expose a larger surface of flame to the atmosphere. It was not, however, necessary to increase the superficial area of the flame;
it could even be diminished with a more intensely luminous effect by having instead of one aperture two small ones pierced at an angle to each other, so that the jets crossed each other a system known as the fishtail or union jet.
Another form was the slit or batwing burner, in which a clean slit was cut across the top of the beak. In the Argand burner a circle of small holes supplied the gas, and a current of air was admitted through the centre of the flame, which was surrounded by a glass chimney. In the Welsbach incandescent lamp the light was produced by causing the burning gas to raise to white heat what is known as the mantle, suspended over the burner. The mantle consisted essentially of cottonyarn steeped in a solution of salts of such metals as thorium, cerium, yttrium, lanthanum, magnesium, etc, and when the thread had been burned away there remained a skeleton of the oxides of the metals used. Research Gas Lighting
A gas mask is a breathing apparatus consisting of an air-tight face piece held tightly across the face by straps at the back of the head and which is fitted with a filter device to strain impurities such as poisonous gasses from the air being inhaled by the wearer, and also protecting the eyes from noxious substances. Gas masks were invented during the Great War in response to the chemical warfare employed on both the German and Allied sides. Research Gas Mask
Gas Oil is a liquid petroleum distillate with a viscosity somewhat below that of lubricating oils. It is used in the manufacture of coal gas and as the charging stock in cracking plants where it is broken down for use as motor spirit. Research Gas Oil
A gas-turbine is a form of engine in which a continuous stream of hot gases is directed against the blades of a turbine, causing it to turn. In most cases the gas, usually air, is first compressed in a compressor before passing into combustionchambers, where a portion of the gas is mixed with fuel and burned. The rest of the gas bypasses the combustion chamber and mixes with the hot gases emerging after combustion. This is then forced through nozzles to drive a turbine. Part of the power from this turbine is used to drive the compressor; the remaining power can be used in various ways, depending on the function of the engine: it may drive the propeller shaft of a turboprop aircraft or ship, the drive-shaft of a locomotive, or an electric generator. Alternatively, a turbine just big enough to drive the compressor can be used, and the remaining energy of the hot exhaust gases used to give a high-speed exhaust jet and hence a forward thrust; this is the jet engine. Gas-turbines are used in electricity generation for standby and peak-load service, in portable power plants, and in combined-cycle power generation. The high power-to-weight ratio of gas-turbines has led to their use in aeroplanes, and also in diesel locomotives and naval vessels. Research Gas-Turbine
A gasket is a compressible packing piece of paper, rubber, asbestos, or other material, sandwiched between the faces of a metal joint to provide a seal. Research Gasket
Gator Edit is a powerful text editor for the Windows operating system that allows you to open up to 100 files simultaneously. It offers many text-formatting and editing tools and has user- configurable toolbars. Gator Edit also comes with a spelling checker, a thesaurus, bookmarking, a search-and-replace function, and the ability to read and export DOS, Unix, and Mac text files.
Gator Edit features a powerful file finder, a Private Clipboard function, and a Toolbar Builder that allows you to build and save as many toolbars as you like. You can customize each toolbar for a given purpose. Dock, float, name, hide, and display them however you like. Research Gator Edit
A gauge is any scientific measuring instrument - for example, a wire gauge or a pressure gauge. The term is also applied to the width of a railroad or tramway track. Research Gauge
In physics, a gauge boson is a boson that mediates the interaction between elementary particles. There are four types: photons for electromagnetic interactions, gluons for strong interactions, intermediate vector bosons for weak interactions, and gravitons for gravitational interactions. Research Gauge Boson
In physics, gauge theory is a type of theory of elementary particles designed to explain the strong, weak, and electromagnetic interactions in terms of exchange of virtual particles. Research Gauge Theory
Gauss is the c.g.s. unit (symbolGs) of magnetic induction or magnetic fluxdensity, replaced by the SI unit, the tesla, but still commonly used. It is equal to one line of magnetic flux per square centimetre. The Earth' s magnetic field is about 0.5 Gs, and changes to it over time are measured in gammas (one gamma equals 10-5 gauss). Research Gauss
Gay-Lussac's barometer was a form of barometer in the form of a siphon. It had two scales with a common zero point, and graduated in contrary directions, the difference between the two levels of mercury being the true height of mercury. Research Gay-Lussac's Barometer
Gay-Lussac's law is the principle that gases react together in volumes (measured at the same temperature and pressure) that bear a simple ratio to each other and to the gaseous products. Research Gay-Lussac's law
A gazogene was an apparatus used during the Victorian period for manufacturing aerated water on a small scale for domestic use, by the combination of an alkali and an acid, such as sodium carbonate and tartaric acid, which yield carbon dioxide when mixed with water. It generally consisted of two globes, one above the other, connected by a tube, the lower for containing water, and the upper the ingredients for producing the gas. The vessel was made air-tight by means of a screw-top, and when water was gently introduced into the upper globe from the lower, by inclining the vessel so as to fill about a half of the former, chemical action takes place, and the carbon dioxide evolved gradually saturated the water in the lower globe. When this had taken place, the aerated water could be drawn off by opening a stop-cock at the top attached to a second tube which reached almost to the bottom of the lower globe. Research Gazogene
GCOS is a quick-and-dirty clone of System/360 DOS that emerged from GE around 1970. Originally it was called GECOS (the General Electric Comprehensive Operating System). Later it was changed to support primitive timesharing and transaction processing. After the buyout of GE's computer division by Honeywell, the name was changed to General Comprehensive Operating System (GCOS). Other OS groups at Honeywell began referring to it as `God's Chosen Operating System', allegedly in reaction to the GCOS crowd's uninformed and snotty attitude about the superiority of their product. Research GCOS
A gear is a toothed wheel that transmits the turning movement of one shaft to another shaft. Gear wheels may be used in pairs, or in threes if both shafts are to turn in the same direction. The
gear ratio - the ratio of the number of teeth on the two wheels - determines the torque ratio, the turning force on the output shaft compared with the turning force on the input shaft. The ratio of the angular velocities of the shafts is the inverse of the gear ratio. The common type of gear for parallel shafts is the spur gear, with straight teeth parallel to the shaft axis. The helical gear has teeth cut along sections of a helix or corkscrew shape; the double form of the helix gear is the most efficient for energy transfer. Bevil gears, with tapering teeth set on the base of a cone, are used to connect intersecting shafts. Research Gear
In machiney, gearing is the parts collectively by which motion communicated to one portion of a machine is transmitted to another, generally a train of toothed wheels. There are two chief sorts of wheel gearing: spur-gearing and bevelled gearing. In the former the teeth are arranged round either the concave or convex surface of a cylindrical wheel in the direction of radii from the centre of the wheel, and are of equal depth throughout. In bevelled gearing the teeth are placed upon a bevelled surface round a wheel which if the slope of the bevel were continued would form a cone, the teeth sloping similarly. Research Gearing
A Geiger counter is any of a number of devices named after Hans Geiger, and used for detecting nuclear radiation and/or measuring its intensity by counting the number of ionising particles produced. It detects the momentary current that passes between electrodes in a suitable gas when a nuclear particle or a radiationpulse causes the ionisation of that gas. The electrodes are connected to electronic devices that enable the number of particles passing to be measured. The increased frequency of measured particles indicates the intensity of radiation. Geiger-Muller, Geiger-Klemperer, and Rutherford-Geiger counters are all devices often referred to loosely as
Geiger counters. Research Geiger counter
The Geissler Tube is a discharge tube made of very hard glass, often of ornamental shape, and exhausted to a pressure of a few millimetres of mercury. Each end of the tube has a platinum wire sealed into it to serve as electrodes. When a discharge of electricity is caused to take place in these tubes by connecting the electrodes to the terminals of a Ruhmkorff's coil or a Holtz's machine, very brilliant effects may be produced. They are used for demonstrating the luminous effects accompanying electric discharges through rarefied gases. Research Geissler Tube
Gelatine is a concrete animal substance, transparent, and soluble slowly in cold water, but rapidly in warm water. It is confined to the solid parts of the body, such as tendons, ligaments, cartilages, and bones, and exists nearly pure in the skin, but it is not contained in any healthy animalfluid. Its leading character is the formation of a tremulous jelly when its solution in boiling water cools.
Gelatine does not exist as such in the animal tissues, but is formed by the action of boiling water. The coarser forms of gelatine from hoofs, hides, etc, are called glue; that from skin and finer membranes is called size; and the purest gelatine, from the air-bladders and other membranes of fish, is called isinglass. With tannin a yellowish white precipitate is thrown down from a solution of gelatine, which forms an elasticadhesive mass, not unlike vegetablegluten, and is a compound of tannin and gelatine. It is this action of tannin on gelatine that is the foundation of the art of tanning leather.
Gelatine when acted upon by sulphuric acid yields gelatine sugar or glycocoll. When treated with potash it is said to yield glycocoll and leucine. Gelatine is nearly related to the proteids. Research Gelatine
Artline by Digital Research, is a program for creating illustrations, mastheads and logos for desktop publishing. With the ability to trace scanned images and seven different zoom levels ranging from 6% to 4000%, its magnifier tool in 100% view shows a screen picture dot for dot as the printed picture would appear on a 300 dots per inch laser printer. The drawing tools include rectangle, ellipse, text and symbol. The symbol selector allows a library of symbols to be loaded and viewed interactively. A sophisticated drawing tool called 'The Quill' can be used to draw straight lines and curves, whether simple, compound or joined. Points on a curve can be selected and moved. Anchor points and direction points can also be shown and curve segments copied. The Quill works with Bezier or spline curves. Text can be edited as graphic elements to produce, for example, trailing shadow effects and can also be arranged around circles and curves. File formats supported include .IMG, .PCX and TIFF. Artline generates GEM or EPS formats
which can be loaded directly into Ventura Publisher or PageMaker. A Bitstream Fontware installation kit is provided and a serif and sans seriftypeface are included with Artline. Research GEM Artline
GEM Draw Plus by Digital Research, is a freehand-drawing program that runs under the GEM/3 desktop. As with other drawing programs, GEM Draw Plus provides a desktop of tools, similar to the way the Macintosh works. You can choose elements such as lines, boxes, circles, and other polygons and text in multiple fonts, sizes, and styles when creating an image. The product can be used to create organisation charts, page borders, floor plans, logos, and other types of diagrams. GEM Draw Plus has a library of over 100 pre-drawn icons and symbols which can be incorporated. Any picture you draw can be stored in your personal picture library and used in other drawings. Because GEM offers a windowing environment, graphics can be cut and pasted between windows.
GEM Draw Plus offers a choice of colours, patterns, line widths, and type styles. The zoom feature uses arrows and scroll bars to display areas of your picture for close detailed work. A Snap command automatically returns you to the spot on the grid where you were last working. Research GEM Draw Plus
Project Gemini was the second phase of the American manned space programme of the 1960's. Gemini followed on from the Mercuryproject and utilised a two-man spacecraft. The object of Gemini was to demonstrate the ability of the astronauts and their spacecraft to manoeuvre in space using manual controls, the feasability and techniques for orbital rendezvous and docking, and various spacecraft systems. Project Gemini was managed by NASA, but the American Department of Defense was also strongly involved and the project had to meet requirements and objectives of both organisations. Twelve flights were made during the Gemini project during the period 1964 to 1965. Research Gemini
Genetic fingerprinting is the pattern of DNAunique to each individual that can be analysed in a sample of blood, saliva, or tissue. It is used as a means of identification in criminal investigations, for example a trace of semen on a rape victim may be used to identify her attacker. Research Genetic Fingerprinting
Genifer was an advanced dBase applications generator for experienced dBase users. It simplified the process of creating sophisticated applications and was an efficient tool for decreasing application development time. The product generated structured and noted application code that could be modified. Database design features included the ability to set default field values, define table, file, or range validation (including displaying an error message if entry is not valid), and defining dBase picture formatting.
Genifer wrote dBase programs by scanning menus, report formats, and data entry screens that were developed with its own text editor or with a word processor. A field-painting character of your choice told Genifer where to place fields. When exiting the text editor or word processor, users could instruct the product where fields were to be created. Genifer was an excellent tool for prototyping applications. It also helped document an application by maintaining a data dictionary that stored information about the databases and the fields, and a layout file that stored all menus, screens, and report layouts. The data dictionary and layout file could be modified and printed. Custom features let you configure Genifer for your own word processor. You could configure the report-page definition and include comments in the dBase program code or help screens in the application.
Genifer supported a full template language that supports all dialects of dBase such as Clipper and FoxBASE+. Research Genifer
Gentian violet is a greenish crystalline substance, obtained from rosaniline, that forms a violet solution in water, and is used as an indicator, antiseptic, and in the treatment of burns. Research Gentian Violet
Geodesy or geodetics is the branch of science concerned with determining the exact position of geographical points and the shape and size of the earth. Research Geodesy
Geognosy is a term which originated among the German mineralogists, and is nearly synonymous with geology. It is the science of the substances which compose the earth or its crust, their structure, position, relative situation and properties. Research Geognosy
In mathematics, the geometrical mean is the second of the terms of a geometrical progression containing three terms. The geometrical mean of two numbers is equal to the square root of their product. Research Geometrical Mean
In mathematics, a geometrical progression is a series of numbers which increase or decrease by equal ratios, for example as, 2, 4, 8, 16, or 16, 8, 4, 2. Research Geometrical Progression
Geometry (from the Greek ge, earth, and metron, measure), as its name implies, was primarily the mathematical science which had for its object the measurement of portions of the earth's surface; but now geometry may be termed the science which treats of the properties and relations of definite portions of space, such as surfaces, volumes, angles, lines. The relation between the parts of the same figure may be of two kinds, of position or of magnitude; for example, two points in a straight line, four points on the same circle, two straight lines perpendicular to one another, a straight line tangent to a circle, are relations of position. On the other hand, the proportionality of homologous lines of two similar figures, the equality of the square constructed on the hypotenuse of a right-angled triangle to the sum of the squares constructed on the sides containing the right angle, that of the volumes of two pyramids on equal bases and of the same height, are relations of dimension. But the relations of position govern the relations of dimension, and vice versa; that is, the one set of relations depend upon the other. Thus it ia because a triangle is rectangular that the square constructed on one of its sides iaequivalent to the sum of the squares constructed on the other two, and, vice versa, that relation between the magnitudes of the squares on the three sides depends on the triangle being right-angled. The geometer may draw indifferently from the study of a figure either the knowledge of the relations of position or that of the relations of dimension, on the condition that he knows how to apply relations of the one kind to those of the other: and the principal aim of geometry is to examine into the connection between the relations of magnitude and those of position.
Geometry may be conveniently divided into several principal sections - elementary geometry, practical geometry, analytical geometry, infinitesimal geometry, etc.
Elementary geometry consists of two parts - plane geometry, the object of which is the study of the simplest figures formed on a plane by straight lines and circles; and solid geometry or geometry of three dimensions, which treats of straight lines and planes considered in any relative position whatever, of figures terminated by planes, of the cylinder, of the cone, and of the sphere.
Analytical geometry, either plane or solid, makes use of the method of co-ordinates introduced by Descartes and primarily applied to curves. In ancient times, though curves were studied and the principal properties of conic sections known, still no connection existed between these curves, nor was there any means of establishing one, so that the study of one was of no value to that of another. The first question in introducing the analytic method was then to fix upon some means which should serve to construct every curve by successive points as numerous and as closely brought together as is necessary in order to lay down the curve, Now the position of a point in a plane may be determined by two intersecting perpendiculars drawn from two fixed lines - the co-ordinate axes - at right angles to each other. An equation may then be found which states the relation between the co-ordinates of any point, that is, its distance from the two co-ordinate axes. The study of the curves will thus be simply the study of their equations. In this way a typical equation for a curve in a certain system may be got, so that if at another time the curve is represented under another definition in investigating its equation in the same system of co-ordinates, particularized so aa to simplify as much as possible the calculations, it will suffice to compare the particular equation with the general one to verify the identity of the curve, to give it its name, and to know all the properties of it which have been studied previously. In a similar way the analytical geometry of solid bodies is based on the fact that the position of any point in space can be determined by reference to three intersecting planes.
Infinitesimal geometry is simply a continuation of the analytical geometry of Descartes, of which it may indeed be said it forms a part; the difference consists simply in the nature of the questions which, as they involve the measurement of magnitudes, the incessantly variable elements of which cannot be summed up by finite parts, require the use of the infinitesimal calculus.
Descriptive geometry consists in the application of geometrical rules to the representation of the figures and the various relations of the forms of bodies according to certain conventional methods. In the descriptive geometry the situation of points in space is represented by their orthographical projections, on two planes at right angles to each other called the planes of projection. Research Geometry
Geophysics is the study of the earth's physical properties and of the physical processes acting upon, above, and within the earth. It includes seismology, geomagnetism, meteorology, and oceanography. Research Geophysics
A geosynchronous orbit is a position at an approximate altitude of 37 km above the Equator, where a velocity of about 2 km per hour in the same direction as Earth's rotation makes a satellite appear stationary over the Earth's surface. At such a point, ground-based microwave antennae can remain fixed and achieve linkage with transponders on board the satellite to produce a microwave relay between points as much as one-third of the way around the globe, or about 13 km; this concept first proposed by British physicist and science fiction writer Arthur C Clarke in a 1947 publication. Research Geosynchronous Orbit
Geothermal energy is energy extracted for heating and electricity generation from natural steam, hot water, or hot dry rocks in the Earth's crust. Water is pumped down through an injection well where it passes through joints in the hot rocks. It rises to the surface through a recovery well and may be converted to steam or run through a heat exchanger. Dry steam may be directed through turbines to produce electricity. It is an important source of energy in volcanically active areas such as Iceland and New Zealand. Research Geothermal Energy
Geranial (citral) is a pleasant-smelling aldehyde which occurs in various essential oils. It can be obtained from lemon-grass oil and is used in the manufacture of perfumes. Research Geranial
German silver also known as nickel silver or pack-fong is an alloy of copper, zinc and nickel. It was first made in Europe at Hildberghausen in Germany, but was invented by the Chinese long before. German silver is made in different proportions, amongst which the following may be mentioned. Spoons and forks were made from two parts copper, one nickel, and one zinc; knife and fork handles were typically made from 5 copper, 2 nickel, 2 zinc, a mixture closely resembling alloyed silver. The addition of lead produces an alloy which appears well fitted for casts, and for making candlesticks, etc. Iron or steel, on the other hand, makes the alloy whiter, harder, and more brittle. German silver is harder than silver, and takes a high polish. It melts at a red heat, the zinc being volatilized in the open air. It is attacked by the strong acids, but it is also affected by common organic acids, such as vinegar, and by some saline solutions. Research German Silver
Germanium is a metal element with the symbolGe used in the manufacture of electronic semiconductors. It has low conductivity at room temperature, but increasing conductivity with increases of temperature. Research Germanium
GetBack by MicroTools Inc. is a full featured GUI backup and restore utility (a text based interface is also present for slower machines). It can backup up to four megabytes per minute. It includes many outstanding features including extensive online help, mouse support, file compression, batch mode operation, point and clickdirectory tree selection, full, incremental and differential backups, and multiple drive support. It formats floppy disks as needed or on demand. Supports all DOS based networks. Research GetBack
GIF (Graphic Interchange Format) is a file format developed in the mid-1980s by CompuServe for use in photo-quality computer bitmap graphics images and now commonly used. Gif images use a 256 bytepalette of 24-bit colours, limiting the image to 256 colours, but allowing each colour to have 256 shades of each of red, green and blue. Research GIF
The GIMP (GIMP is an acronym for GNU Image Manipulation Program) is a computer software application that started as an undergraduate project by Peter Mattis and Spencer Kimball at the University of California and has evolved into an application designed for retouching photographs, composing and authoring images. Its powerful capabilities as an image manipulation program make it a worthy competitor to other similar programs such as AdobePhotoshop or Corel PhotoPaint, but the biggest advantage of The GIMP is it's free availability although it's not freeware, rather it is an OSS (Open Source Software) program covered by the GPL license, which gives the user the freedom to access and also to change the source code that makes up the program. The Gimp offers a full suite of painting tools including brushes, a pencil, an airbrush, an ink tool, and cloning. Tile-based memory management so image size is limited only by available disk space; sub-pixel sampling for all paint tools, allowing for high-quality anti-aliasing; full Alpha channel
(transparency) support; layers and channels. Advanced scripting capabilities provided by a procedural database so you can call internal GIMP functions from external scripts, such as Script-Fu, Perl-Fu (Perl scripts) and Python-Fu (Python scripts). The GIMP offers multiple undo and redo, limited only by disk space; transformation tools including rotate, scale, shear, and flip. File formats supported include PostScript, JPEG, GIF, PNG, XPM, TIFF, TGA, MPEG, PCX, BMP and many others. Selection tools including rectangular, elliptical, free, fuzzy, paths, and intelligent scissors. The GIMP supports plug-ins that allow for the easy addition of new functions, new file formats, and new effects filters. The GIMP is probably best known for its use on the GNU/Linux platform, but there are many platforms that GIMP can run on, including GNU/Linux, Microsoft Windows 95, 98, NT4 and 2000, OpenBSD, NetBSD, FreeBSD, Solaris, SunOS, AIX, HP-UX, Tru64, Digital Unix, OSF/1, IRIX, OS/2 and BeOS. Research Gimp
Gin is the name of certain machines employed in raising weights. One form consists of three poles, 12 to 15 feet long, often tapering from the lower extremity to the top and united at their upper extremities whence a block and tackle is suspended. A space of 8 or 9 ft. separates the lower extremities planted in the ground, and a kind of windlass is attached to two of the legs. Another kind of gin was a sort of whim or windlass for raising coal, etc. It was worked by a horse, which turned a cylinder, which wound on it a rope, by which the weight was raised. Research Gin
Giobertine tincture is a preparation for restoring illegible writings or faded pictures. The inventor of it was Giovanni Antonio Gioberti (born in 1761, died in 1824), a native of Piedmont. Research Giobertine Tincture
Glass is an artificial hard, brittle, transparent or translucent, noncrystalline solid, consisting of metal silicates or similar compounds fused with an alkali. In its finest qualities glass is quite transparent, and is used for making windows, mirrors, bottles, composite armour plate for armoured fighting vehicles etc.
The ancient Egyptians carried the art of making glass to great perfection, and are known to have practised it as early as 2000 BC, if not earlier. The Assyrians, the Phoenicians, the Greeks and Etruscans were all acquainted with the manufacture. The Romans attained peculiar excellence in glass-making, and among them it was applied to a great variety of purposes. Among the most beautiful specimens of their art are the vases adorned with engraved figures in relief; they were sometimes transparent, sometimes of different colours on a dark ground, and very delicately executed. The Portland or Barberini vase is almost the only surviving specimen of this kind. The mode of preparing glass was known long before it was thought of making windows of it. The first mention of this mode of using glass is to be found in
Lactantius, in the 3rd century AD. St Jerome also speaks of glass being so used in 422 AD.
Benedict Biscop introduced glass windows into Britain in 674 AD. In church windows it was used from the 3rd century. The Venetians were long celebrated for their glass manufacture, which was established before 700 AD. Britain did not become distinguished for glass until about the commencement of the 16th century.
The excise laws relative to the glass manufacture were at one time complicated in the extreme, and tended to check improvements in glass-making. These laws were repealed in 1845 by Sir Robert Peel, as part of his free-trade policy, and beneficial effects were immediately apparent in the improved quality, cheapness, and greater variety of descriptions of glass produced. Traditionally, glass is largely made in France, Germany, Belgium, and the United States. For coloured glass Bohemia has long had a high reputation.
The first mention of the manufacture of glass in the United States is in Captain John Smith's 'History of Virginia', in which he speaks of a glass factory having been founded at Jamestown in 1615, and a second in 1622. The work was coarse, being chiefly confined to bottles. In 1754, a successful factory was established in Brooklyn by Bamper, a Dutchman. In 1779, factories were founded at Temple, New Hampshire, and in 1795 the industry was begun at Pittsburgh. By 1813 there were five glass factories at Pittsburgh. In 1840 there were eighty-one factories in the United States, by 1870, 201 factories flourished in different places and since then the industry rapidly increased.
Glass is formed by the fusion of siliceous matter, such as powdered flint or fine sand, together with some alkali, alkaline earth, salt, or metallic oxide. The nature of the glass will depend upon the quality and proportion of the ingredients of which it is formed; and thus an infinite variety of kinds of glass may be made, but in commerce five kinds are usually recognized:
1. Bottle or coarse green glass. 2. Broad, spread, or sheet window-glass. 3. Crown-glass, or the best window-glass. 4. Plate-glass, or glass of pure soda. 5. Flint-glass, or glass of lead.
Coloured glass may be mentioned as a sixth kind. The physical properties of glass are of the highest importance. Perhaps the chief of these is its transparency, and next to that its resistance to acids (except hydrofluoric acid). It preserves its transparency in a considerable heat, and its expansibility is less than that of any other known solid. Its great ductility, when heated, is also a remarkable property. It can, in this state, be drawn into all shapes, and even be spun into the finest threads. It is a bad conductor of heat, and is very brittle. It is usually cut by the diamond.
The works in which glass is made are called glass-houses. They were traditionally constructed of brick, and made of conical form. A large vault was made in the interior of the cone, extending from side to side, and of sufficient height to allow workmen to wheel in and out rubbish from beneath the furnace, which was placed over the vault, and separated from it by an iron grating. The materials used for the formation of the glass are sometimes calcined in a calcar or fritting furnace, and a chemical union between the ingredients commenced, forming a frit. But this process is not essential, and the materials, after being ground and thoroughly mixed up together, are usually placed at once in melting pots or crucibles made of Stourbridgefire-clay, or other similar material, the melting-pots being then placed in the melting furnace or oven. This is a kind of reverberatory furnace, traditionally circular in form, arched or domed above, and capable of keeping up an intense heat. The crucibles are placed in the furnace at equal distances from each other round the circumference, each pot being opposite to an opening in the wall of the furnace in order that the crucible may be charged or discharged by the workman from without. In the 19th century a furnace called a tankfurnace came into use which enabled melting pots to be dispensed with, as the material could be melted in and worked from the furnace directly.
The use of the annealingfurnace, is also essential in glass-making, the process of allowing the glass to cool there being called annealing. Unless this process be carefully managed, the articles formed in the glass-house can be of no use, from their liability to break by the slightest scratch or change of temperature.
Sheet glass is the commonest description of glass. It is composed of various ingredients in varying proportions, usually of sand, chalk, or limestone, sulphate of soda, and cullet or broken glass. A coarse variety of it may be made of a mixture of two parts by measure of soap-boilers' waste, one of soda-ash and one of cleaned sand. In France the materials employed are commonly: sand 100 parts, sulphate of soda 30, carbonate of lime 30, coke to aid in the reduction of the sulphate of soda 5, with some bioxide of manganese to correct the greenish tinge that glass with a soda base possesses. Traditionally when the materials were properly melted a quantity was taken out of the pot on the end of an iron tube about 5 feet long, and the workman by blowing into and swinging the tube while heating and reheating the glass, imparted a cylindrical shape to the newly-formed product. The rounded extremity of the cylinder (which was about 4 feet long or more) was softened in the furnace in order to enable the workman to blow a hole in it. This opening was made by heating the cylinder and then stopping up the tube with the thumb, when the expansion of the air caused the cylinder to burst open at the end. The other rounded end was detached after cooling by winding round its circumference a thread of red hot glass, which caused a clear fracture. The cylinder was then split open parallel to its axis by a diamond, and then conveyed to the flattening furnace where it was heated and opened out into a flat sheet of glass. It was afterwards placed in the annealingfurnace.
Crown glass is differently formed by different makers, but its composition is essentially the same as the best sheet glass. It used to be the only window-glass made in Britain, but its manufacture had been almost or altogether superseded by that of sheet glass by the start of the 20th century. The ingredients being melted and at the proper temperature, a quantity of the glass was withdrawn by the tube (to the amount, by successive addition, usually of 10 lbs in all). By various manipulations this from having the form of a hollow oblate spheroid was made to assume the form of a thin circular plate, with a thick part called the bull's eye in the centre, being the point at which an iron rod was attached to it for the purpose of causing it to revolve rapidly and spread out into a sheet before the furnace. The bull's eye used to be commonly seen in the windows of humble dwellings, the pieces of glass containing them being cheap.
Flint-glass or Crystal is one of the kinds largely made, being employed especially for table utensils, globes, ornaments, etc. Powdered flint was formerly employed in its manufacture, but fine white sand has been substituted. The other materials are red-lead or litharge, and pearl-ash (carbonate of potash). The following is said to be a good mixture : Fine white sand, 300 parts; red-lead or litharge, 200; refined pearl-ash, 86; nitre, 20; with a small quantity of arsenic and manganese. The furnace is kept at a very high temperature until the whole of the materials are fused. When the glass becomes translucent the temperature is diminished until it becomes a tenacious mass. Suppose a glass vessel is to be made, the iron tube is put into the crucible, and the required quantity of glass lifted out, which after certain adjustments is rolled into a cylindrical form on an iron table called the merver or marver. The workman
then blows the glass into the form of a hollow globe, and re-heats and blows until the globe becomes of the required thinness. An iron rod called the punty is now attached to the end of the glass furthest from the tube, and the tube detached. The workman now heats the glass on the punty, and sitting down upon a chair with smooth arms, he lays the punty upon them, and rolling it with his left hand he gives the glass a rotatory motion, while with an instrument in his right, somewhat like a pair of sugar-tongs, he enlarges or contracts the different parts of the vessel until it assumes the requisite shape. A pair of shear's is al.so made use of in certain cases. The article is then detached from the punty, and carried to the annealingfurnace. Many of the articles, after coming from the annealingfurnace, are sent to the cutter or grinder. The operation of grinding is performed by wheels of various diameter and of various edges, some of iron, others of stone, and some of wood. Rich and delicate designs may be cut upon the articles by means of small wheels of copper and steel upon which emery is kept constantly falling.
Ornamental figures may also be engraved, or rather etched, upon articles of glass by means of hydrofluoric acid, care being taken to place a coating of some substance over the parts not to be acted upon. Various ornamental forms are given to the surface of glass vessels by metallic moulds. The mould is usually of copper, with the figure cut on its inside, and opens with hinges to permit the glass to be taken out. The angles of moulded objects are always less sharp than those of cut-glass.
Green or bottle-glass is formed of the coarsest materials, such as coarse sea or river sand, lime, and clay, and the most inferior alkalies, as soap-boilers' waste, and the slag of iron ore. A cheap mixture for this kind of glass may be made of common sand and lime, with a little clay and sea salt. The manipulations of the traditional glass-blower in fashioning bottle-glass into various forms were in general the same as those performed by the flint-glass blower. Wine and beer bottles, which are required to be all of a certain capacity, are blown in moulds, so that their containing portion may be as nearly as possible of the requisite size. When the articles are made they are carried to the annealingfurnace. Green bottle-glass is preferable to all other kinds for vessels required to contain corrosive substances; it is less fusible than flint glass, and
thus is better calculated for many chemical purposes.
Plate-glass is a fine and thick glass cast in sheets. One maker's ingredients are as follows: white sand, 300 lbs; soda, 200; lime, 30; oxide of manganese, 2; oxide of cobalt, 3 ounces; and fragments of glass (cullet) equal to the weight of sand. After being melted in large crucibles, and the liquid glass having been thoroughly skimmed, it is transferred by a copper ladle to smaller pots (cuvettes). When the glass in the smaller crucible is ready for casting it is poured upon an iron casting-table, and a large metal cylinder moved along spreads the glass into a broad uniformsheet. The subsequent stages of the process are concerned with the discovery of flaws, the squaring of the edges, the grinding of the surfaces plane, the grinding of the sides, and the polishing. Before grinding and polishing the glass is what is called common 'rough plate,' and in this state it is much used for roofing, cellar-lighting, etc, being non-transparent. 'Rolled plate,' which is cast on a table that imparts a surface of grooves, flutings, lines, etc, is extensively used for the same purposes.
There are several other kinds of glass that may be noticed. Pressed glass is flint-glass formed into articles by pressing into moulds of iron or bronze, a fine surface being afterwards attained by heating so that a thin film on the surface melts.
Slag glass is glass from the slag of blast-furnaces mixed with other ingredients; it is largely used for bottles.
Optical glass is made of special varieties of flint and crown glass.
Strass, which was used for imitating gems, was a very dense flint-glass, colours being imparted by metallic oxides.
Spun glass is glass in the form of very fine threads, in which state it may be woven into textile fabrics of great beauty.
Toughened or hardened glass, having certain properties owing to its being heated to the melting point and plunged into an oleaginous mixture, was invented prior to the start of the 20th century, but was not developed into a working product until the mid-20th century, and is now very commonly used for windows.
Coloured glass is of two kinds - entirely coloured, the colouring matter being melted along with the other ingredients; or partially coloured, a quantity of white glass being gathered from one pot, and dipped into the other containing the coloured glass, by which the whole receives a skin of coloured glass. The colouring matters are chiefly the metallic oxides. A beautiful yellow colour is imparted by silver in union with alumina (powdered clay and chloride of silver being used), also by uranium and by glass of antimony; red colours by oxide of iron, copper, and gold; green by protoxide of iron, oxide of copper, oxide of chromium, &c.; blue by cobalt; orange by peroxide of iron with chloride of silver. ohemia is particularly famous for its manufactures of articles in coloured glass. Research Glass
Glauber's salt or Glauber salt is the crystalline decahydrate of sodium sulphate. It is so called because of the importance attached to its chemical and medicinal properties by Johann Glauber. It forms large colourless mono-clinic prisms, which effloresce on exposure to the air. It is soluble in water, and when heated melts in its water of crystallization. It is found in many localities, both dissolved in the water of mineral-springs and of saltlakes, round which it effloresces. Research Glauber's Salt
Glazing is the covering of earthenware (pottery) vessels with a vitreous coating in order to prevent their being penetrated by fluids. Research Glazing
Gliadin is a protein of cereals, found especially in wheat, with a high proline content. It forms a sticky mass with water that binds flour into dough. Research Gliadin
In computing, the term globing refers to the ability to group sets of filenames with a pattern, known as the globing pattern. Special characters, such as the asterisk and question mark, are interpreted and expanded by the shell. Research Globing
Gloss paint is a type of paint composed of pigments ground up in a varnish medium, which produces a hard, shiny, and usually durable finish. Research Gloss Paint
Glucic Acid is an acid produced by the action of alkalis on glucose or of acids on cane-sugar. It is a colourless substance, is very soluble in water, attracts rapidly the moisture of the air, and its solution has a decidedly sour taste. All its neutral salts are soluble. Research Glucic Acid
Glucina is the only oxide of the metal glucinum or beryllium. It is white, tasteless, without odour, and quite insoluble in water, but soluble in the liquid fixed alkalies. Its formula is BeO. Research Glucina
The glucosides are a group of carbon compounds occurring in plants, and characterised by the fact that on hydrolysis or saponification with dilute acids a sugar, usually glucose, is formed along with other products. Research Glucoside
Glutathione (GSH) is a tripeptide and accounts for over 90% of the intracellular non-protein thiols where it functions as an antioxidant and in the activation of T cells. It is especially important in the intracellular removal of the free radical gydrogen peroxide because it provides a substrate for glutathione peroxidase, the major hydrogen peroxide removing enzyme in humans. GSH is present in foods in very small amounts, and is synthesised in the body from other peptides - cysteine, glycine and glutamine. Cysteine and overall proteinintake are very important for the synthesis of GSH. Research Glutathione
Glutelin is a group of plant proteins found in cereals. They are insoluble in water, precipitated by alcohol and are not coagulated by heat. Research Glutelin
Gluten is a tough elasticprotein of a greyish colour which becomes brown and brittle by drying, found in the flour of wheat and other grain. It contributes much to the nutritive quality of flour, and gives tenacity to its paste. Research Gluten
Glycerol is a colourless or pale yellow odourless sweet-tasting syrupy liquid; 1,2,3-propanetriol. It is a by-product of soap manufacture and is used as a solvent, antifreeze, plasticiser, and sweetener (E422). Research Glycerol
Glyceryl monostearate is an emulsifier widely used in processed foods. It is hydrophilic (water soluble) at the glycerol end and lyophilic (fat soluble) at the stearate end. Research Glyceryl Monostearate
Glycol ethers are general solvents, also known as cellosolves, which are used in the semiconductor industry. They are also used in surface coatings, such as lacquers, paints, and varnishes; fingernail polishes and removers; dyes; writing inks; cleaners; and degreasers. Three important
glycol ethers are ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether. All glycol ethers have a low vapour pressure and a high potential for dermal absorption. They are non-flammable. Research Glycol ether
Glycolic acid is a colourless crystalline soluble hygroscopic compound found in sugar cane and sugar beet. It is used in tanning and in the manufacture of pharmaceuticals, pesticides, adhesives, and plasticisers. Research Glycolic Acid
Glyptal is an alkyd resin obtained from polyhydric alcohols and polybasic organic acids or their anhydrides. It is used for surface coatings. Research Glyptal
GNOME (GNU Network Object Model Environment) is a popular graphical user interface for X Windows designed to be an effective desktop and flexible and sophisticated developer's environment. Research GNOME
GNU (GNU's Not Unix) is a project initiated during the early 1980s by Richard Stallman with the aim of providing a free replacement for the BerkeleyUNIXcomputer operating system. GNU is designed to be freely copyable, and users are encouraged to improve it and submit their changes to the GNU library. Research GNU
A Goldschmidt Alternator is a dynamo-electric ac generator for producing currents of high frequency. A number of windings arranged alternatively on the rotor and the stator are tuned to successively high frequencies. Currents of one frequency in one of the coils, say on the rotor, produce currents of higher frequency in one of the stator coils, and these in turn produce currents of still higher frequencies in the next rotor coil. The process continues for the complete series of coils, and frequencies up to some 100 kHz can be produced. Research Goldschmidt Alternator
A goniometer is an instrument for measuring solid angles, and is used in crystallography. The reflecting goniometer is an instrument of this kind for measuring the angles of crystals by determining through what angular space the crystal must be turned so that two rays reflected from two surfaces successively shall have the same direction. Research Goniometer
Gopher is a now defunct computer program developed at the University of Minnesota, which was formerly used to retrieve information from the internet. Like Archie, or a modern search engine,
gopher was a program that enabled users to access a database of indexed information resources, and would return documents matching an entered search word or phrase. Research Gopher
A gouge is a form of chisel with a blade curved lengthwise to form a partial cylinder. The bevel can be on either the convex or concave side. Gouges are used for carving or scooping out grooves in wood and for tooling leather &c. Research Gouge
In mechanics, a governor is a contrivance for maintaining a uniformvelocity with a varying resistance of a piece of machinery. Originally, governors were employed in steam engines and worked by regulating the amount of steam that passed. A common form of steam-engine governor consisted of a pair of balls suspended from a vertical shaft kept in motion by the engine. When the engine went too fast the balls flew farther asunder, and depressed the end of a lever, which partly shut a throttle-valve, and diminished the quantity of steam admitted into the cylinder; and on the other hand, when the engine went too slow, the balls fell down towards the spindle and elevated the valve, thus increasing the quantity of steam admitted into the cylinder. By this ingenious contrivance, therefore, the quantity of steam admitted to the cylinder was exactly
proportioned to the resistance of the engine, and the velocity kept constantly the same. A similar contrivance was employed in mills to equalize the motion of the machinery. When any part of the machinery was suddenly stopped, or suddenly set agoing, and the moving power remained the same, an alteration in the velocity of the mill would take place, and it moved faster or slower. A governor was used to remedy this. Research Governor
Graduation is the art of dividing into the necessary spaces the scales of mathematical, astronomical, and other philosophical instruments. Common graduation is simply effected by copying from a scale prepared by a higher process; original graduation is chiefly performed either by stepping or bisection. Stepping consists in ascertaining by repeated trial with finely-pointed spring-dividers - which are made, as it were, to proceed by successive steps - the size of the divisions required, their number being known, and then finally marking them.
In bisection the beam compasses are used, an arc with a radius of nearly half the line being described from either end of the line, and the short distance between the arcs bisected with the aid of a magnifier and a fine pointer. The process is repeated, for each of the two halves thus obtained, until by subdivision the required graduation is obtained.
Ordinary instruments are graduated by machines, most of which are based upon the principle of that invented by Ramsden in 1766. In this there is a horizontal wheel, turning on a vertical axis, with a toothed edge which is advanced a certain amount (e.g. 10 minutes of arc) by each revolution of the endless screw with which it gears. The screw is worked by a treadle, and the machine can be so adjusted that a movement of the treadle shall secure either the whole or any desired part of a revolution of the screw.
A dividing engine was invented by Troughton, but it was exceedingly complicated. That of Simms, which was self-acting and threw itself out of gear when its work was done, takes a high place among mechanical inventions. The most accurate of the early graduation machineswas that produced in 1831 by Andrew Ross. For fine graduation Proment invented a machine in which the object to be graduated was slowly and intermittingly pushed forward by a screw, while a fine steel or diamond point, working automatically, made a cut at each cessation of the feeding motion. He thus drew 25,000 lines marking equal intervals in the space of one inch, but the number was since increased to 225,000 by Nobert. These nachines now appear very crude since the advent of modern electronics and the laser. Research Graduation
Graham's law of diffusion (also known simply as Graham's Law) states: At constant temperature gases diffuse at rates which are inversely proportional to the square roots of their densities. The law was formulated in 1829 by Thomas Graham. Research Graham's Law of Diffusion
Gram's stain is a method of staining, developed in 1884 by H C J Gram, which is used to differentiate bacteria. The bacterial sample is smeared on a microscope slide, stained with a violet dye, treated with acetone-alcohol, and finally counterstained with a red dye. Gram-positive bacteria retain the first dye, appearing blue-black under the microscope. In Gram-negative bacteria, the acetone-alcohol washes out the violet dye and the counterstain is taken up, the cells appearing red. Research Gram's Stain
A gramaphone is a now almost obsolete device for replaying sound recordings made on plastic disks. A disk was engraved with a spiral pattern of grooves, and the recording reproduced by a blunt stylus of sapphire or diamond which transmitted the bumps of travelling over the grooves to a sensitive material, originally glass or mica which then vibrated reproducing the original sound waves. The sound was then passed to an amplifier, originally a horn and later an electronic amplifier. The recordings for a gramaphone were made by a phonograph, the original invented in 1877 by Thomas Edison which recorded the sound on tinfoil, and later improved by Tainter to engrave wax disks instead. Research Gramaphone
Micrografx Graph Plus is a Windows-based business-presentation program designed for creating area, bar, column, line, pie, scatter, and table charts. Charts can be enhanced to produce three- dimensional, ranked, shadowed, logarithmic, and log-log charts. Graph Plus lets you create and rotate chart titles (single or multiline) and labels. The program is a good data-analysis tool.
Graph Plus runs under Microsoft Windows 2.0 or above and takes advantage of Window's Dynamic Data Exchange (DDE), and links applications to allow the transparent sharing of data between two Windows applications. This provides automatic updating of charts as data changes.
Graph Plus uses a worksheet to enter or import labels and data values. The worksheet offers basic spreadsheet functions such as sorting, totalling, and addition and subtraction of rows and columns. Research Graph Plus
Graphology is the study of a person's handwriting to obtain information about his or her personality. Its practice is widespread in ContinentalEurope, and in particular in Belgium, France, Germany, the Netherlands, and Switzerland with many firms consulting graphologists for advice about which people to hire. Research Graphology
The graphoscope is an optical apparatus used for magnifying and giving fine effects to engravings, photographs etc. It was invented by Riswell and first exhibited in 1871. Research Graphoscope
Graphotype was a process for obtaining blocks for surface-printing invented by Witt Hitchcock in 1860. Drawings were made on blocks of chalk with a silicious ink. When the ink dried, the soft parts were brushed away leaving the drawing in relief and stereotypes could then be taken from the block. Research Graphotype
Gravitation is the force by reason of which all the bodies and particles of matter in the universe tend towards one another. According to the law of gravitation discovered by Isaac Newton, every portion of matter attracts every other portion with a force directly proportional to the product of the two masses, and inversely proportional to the square of the distance between them. Kepler had given the laws, deduced from observation, according to which the planets describe their orbits. From these Isaac Newton deduced the laws of the force in the case of the planets and subsequently he generalized the statement of them, by showing the identity of the nature of the force that retains the moon in her orbit, with that which attracts matter near to the surface of the earth.
The application of the grand law that he had discovered subsequently occupied a large part of the mathematical labours of Isaac Newton. Attacking the problem of lunar inequalities, he accounted for them by considering the perturbations due to the attraction of various bodies of the solar system; and by accounting for all the observed perturbations by means of his newly-discovered law he confirmed the truth of the law itself in such a way as to put it beyond all question.
The computation of these various attractions has reached such a degree of accuracy in the hands of mathematicians since Isaac Newton, that the most complicated motions of the heavenly bodies can be predicted. The law has also been applied successfully in weighing the planets, explaining the paths of comets, the motions of the tidal wave, etc. It has also been demonstrated to hold good in the case of comparatively small bodies. Thus Maskelyne determined the attraction of a particular mountain, and Cavendish and Bailly measured the attraction of balls of lead on light finely-balanced bodies, and thus determined the mean density of the earth. Research Gravitation
Gravity is the term applied to the force with which the earth attracts every particle of matter (gravitation). The force of gravity is least at the equator, and gradually increases as we recede toward the poles. Thus a given mass, if tested by means of a spring-balance of sufficient delicacy, would appear to weigh least at the equator, and would seem to get heavier and heavier as the latitude increases. This is due to two causes: first, the centrifugal force at the equator is greater than that in high latitudes, because of the greater radius of the circle described at that place; and, second, the attraction is diminished by the greater distance of objects on the surface from the earth's centre. From both causes combined a body which weighs 194 lbs. at the equator would weigh 195 lbs. at either pole. Experiments to determine the force of gravity from point to point are made by determining the length of a pendulum that beats seconds at each place. By experiments made by Captain Kater at Leith Port it was found that the force of gravity at that place is such that a body, unresisted by air or otherwise, would acquire in one second, under its influence, a velocity of 32.207 feet per second. At Greenwich the acceleration is 32.1912 feet. The term gravity is now popularly used in place of the term gravitation. Research Gravity
Green is one of the three primary colours of light and one of the three secondary colours of pigment mixtures, being obtained by mixing blue and yellow. Research Green
Grep (Global Regular Expression and Print) is an originally Unix, now widely available computer program that evolved from the Unix editor 'Ed'. Grep searches a named input file or files (or standard input if no files are named) for lines containing a match to a given pattern. Research Grep
In horology, a gridiron-pendulum is a compensation pendulum in which the bob is supported by parallel bars of two metals which are unequally expanded by heat. These are so disposed that, while one tends to lengthen, the other tends to shorten. Research Gridiron-Pendulum
A gridiron-valve was a type of valve found in steam engines, whose opening was divided into a number of narrow parts by which the travel could be abridged and the more rapid opening or closing of the valve affected. Research Gridiron-Valve
In weaving, a griff is a series of horizontal, parallel-edged bars, also known as knives or blades, arranged in a reciprocating frame to raise and lower the vertical hooked rods connected to the shedding mechanism, when the hooked ends of the rods are brought by a pattern device within the path of the knives. Research Griff
Grimaldi's Fringes is a term in optics given to the coloured bands observed when a beam of light passing through a narrow slit falls on a screen. They are due to the interference of the luminous waves and are named after Francesco Grimaldi who wrote a treatise on the subject. Research Grimaldi's Fringes
A grub-saw is a hand-saw used for cutting marble into strips. It has a steel blade, notched at the edge and stiffened by a backing of wood similar to the metal back of a tenon-saw. Research Grub-Saw
Guano is a manure consisting of the excreta of fish-eating sea-fowl, such as gulls, cormorants, and penguins, and of walruses, seals and the like together with other animal remains including birds' feathers and bones.
Guano is high in nitrogenous substances and phosphates and other chemicals. Research Guano
Gum-arabic is the purest form of gum, and may be regarded as typical. It comes from various species of Acacia, such as the Acaciavera, Acacia seyal, and Acacia arabica or nilotica. The gum exudes spontaneously, and its appearance is an indication of the tree being in an unhealthy condition; but in order to get it in sufficient quantity incisions are made in the bark. Gum-arabic is very largely employed in the finishing and dressing of fabrics; for thickening the colours in calico-printing; in pharmacy; as a cement; in ink-making; for making crayons and water-colour cakes, and for many other purposes. The purest gum-arabic is in round tears, transparent, and almost colourless, faintly odorous, completely soluble in water, the solution being feebly acid. Research Gum Arabic
Gun metal is an alloy of 90 copper to 10 tin (or sometimes zinc rather than tin or sometimes less copper and a small amount of zinc). It is a typical bronze, formerly used for making cannons (whence it gets its name) and is still used for bearings and other parts that require a high resistance to wear and corrosion. Research Gun Metal
Gunite is a cement-sand mortar that is sprayed onto formwork, walls, or rock by a compressed air ejector giving a very dense strong concrete layer. It is used to repair reinforced concrete, to line tunnel walls or mine airways, etc. Research Gunite
Gunnery is the science of conducting the fire of artillery. Gunnery may be divided into the theoretical and practical branches. The former consists chiefly in the application of mathematics to the solution of the problems in dynamics involved in the consideration of the motion of shot through the air, and is essential to the design of good systems of rifling and well-proportioned projectiles.
Practical gunnery, which deals with the actual firing, has reference rather to the use of individual guns than to the handling of artillery on a large scale. The line taken by a projectile in its passage through the air to the first point of impact is called its trajectory. This is always a curve, since though the force of the powder tends to propel the projectile in a straight line, the force of the earth's gravity begins to drag it down on leaving the gun; the trajectory is also subject to modifications caused by the resistance of the air, the form of the shot, etc. Among things to be considered in gunnery are the velocity of the projectile, initial and subsequent, the angle of elevation of the piece, the range or distance to which the projectile is carried, etc.
The trajectory is more curved with a low-velocity gun than with a high-velocity one; hence to obtain the same range the former must have a greater angle of elevation above the horizontal plane. To allow for the fall of the projectile it is necessary to point the axis of the bore of the gun as much above the mark aimed at as the projectile would have fallen below if the gun had been pointed Straight. Hence the use of sights both for small arms and heavy guns. The latter have usually what is called a 'tangent scale' at the breech and a foresight at the muzzle to enable the piece to be aimed suitably. In order to know how to aim a gun so as to hit an object, its range or distance must be found. This may be done by trial, that is by firing several experimental shots; but special instruments known as range-finders have been in use since the start of the 20th century, the principle on which they are constructed being that of measuring the angle subtended at the object by a known base - the base being at the instrument itself.
In determining the velocity of projectiles various instruments were formerly used. Among these were Wheatstone's electro-magnetic chronoscope, the Bashforth chronograph, the Noble chronoscope, etc.
Horizontal fire against the front of a column or line of works is termed direct fire ; that which sweeps along a line of men or earth-works, enfilade fire, high angle and vertical fire is when the piece is fired at a high angle of elevation. Research Gunnery
Gutta-percha is a tough plastic-like substance resembling caoutchouc in many of its properties, but stronger, more soluble, and less elastic. It is the inspissated milky juice of Isonandra Gutta and other kindred trees of the natural order Sapotaceae. It chiefly comes from Malacca, Borneo, and other islands of the MalayArchipelago. When pure, gutta-percha is of a brownish-red colour. Below the temperature of 50 degrees Fahrenheit it is as hard as wood and excessively tough. By an increase of heat it becomes more flexible, until at a temperature of 115 degrees Fahrenheit it becomes pasty, and between this and 140 degrees or 150 degrees it may be moulded into all varieties of forms with the greatest ease, retaining precisely the same form as it cools and hardens to its previous state of rigidity. It is insoluble in water, soluble with difficulty in ether and other caoutchouc solvents, but very readily in oil of turpentine and naphtha. It is not attacked by solutions of alkalies nor by hydrofluoric acid, but it is acted on by sulphuric, nitric, and hydrochloric acids.
Gutta-percha has formerly been applied to a variety of purposes since before the 20th century and the invention of artificial plastics, for example as a substitute for leather, especially in the soles of shoes, etc, as an insulating coating for the copperwires of submarine telegraph cables, as an ingredient in mastics and cements, for the manufacture of flexible hose-tubes, bottles, etc. Research Gutta-percha
A gyroscope is any rotating body that exhibits two fundamental properties: gyroscopic inertia, or rigidity in space, and precession, the tilting of the axis at right angles to any force tending to alter the plane of rotation. These properties are inherent in all rotating bodies, including the earth itself. The term gyroscope is commonly applied to spherical, wheel-shaped, or disk-shaped bodies that are universally mounted to be free to rotate in any direction; they are used to demonstrate these properties or to indicate movements in space. A gyroscope that is constrained from moving around one axis other than the axis of rotation is sometimes called a gyrostat. In nearly all its practical applications, the gyroscope is constrained or controlled this way, and the prefix gyro is customarily added to the name of the application, as, for instance, gyrocompass, gyrostabiliser, and gyropilot. Research Gyroscope
Gyroscopic inertia is the rigidity in space of a gyroscope. It is a consequence of Newton's first law of motion which states that a body tends to continue in its state of rest or uniform motion unless subject to outside forces. Thus, the wheel of a gyroscope, when started spinning, tends to continue to rotate in the same plane about the same axis in space. An example of this tendency is a spinning top, which has freedom about two axes in addition to the spinningaxis. Another example is a riflebullet that, because it spins or revolves in flight, exhibits gyroscopic inertia, tending to maintain a straighter line of flight than it would if not rotating. Rigidity in space can best be demonstrated, however, by a model gyroscope consisting of a flywheel supported in rings in such a way that the axle of the flywheel can assume any angle in space.
When the flywheel is spinning, the model can be moved about, tipped, or turned at the will of the demonstrator, but the flywheel will maintain its original plane of rotation as long as it continues to spin with sufficient velocity to overcome the friction with its supporting bearings. Gyroscopes constitute an important part of automatic-navigation or inertial-guidance systems in aircraft, spacecraft, guided missiles, rockets, and ships and submarines. In these systems, inertial-guidance instruments comprise gyroscopes and accelerometers that continuously calculate exact speed and direction of the craft in motion. These signals are fed into a computer, which records and compensates for course aberrations.
The most advanced research craft and missiles also obtain guidance from so-called laser gyros, which are not really inertial devices but instead measure changes in counter rotating beams of laser light caused by changes in craft direction. Another advanced system, called the electrically suspended gyro, uses a hollow berylliumsphere suspended in a magnetic cradle; fibre-optic systems are also being developed. Research Gyroscopic Inertia
Gzexe is a computer program for Unix that compresses executable files in place so that they automatically uncompress and execute when executed although there is a penalty in performance, as the computer system needs to uncompress the program before executing it. Research Gzexe
Gzip is a computer program available on Windows and Unix platforms, that reduces the size of specified files using Lempel-Ziv coding (LZ77). Research Gzip
Abbreviations
SciTech
Research G6-233
