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An F Connector is a two-wire (signal and ground) coaxial cable connector used to connect RF frequency signals (aerials, televisions and VCRs etc as well as broadband telephony signals). The plug's shell and socket are threaded ensuring a tight connection and reliability.
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The F Layer is a region of the ionised gas in the ionosphere, often known as the Appleton Layer. It is the most important layer from the point of view of long-distance radio communications.
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In engineering, the term face refers to the flattening and smoothing of a surface.
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In engineering, a face plate is a plate attached to the spindle of a lathe, to which the work to be turned may be attached. In engineering, a face plate is a covering plate for an object, used to receive wear or shock, thereby protecting the object.
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In engineering, a face wheel is a wheel whose disk face is adapted for grinding and polishing.
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In founding, the term facing refers to a powdered substance, such as charcoal, bituminous coal, &c., which is applied to the face of a mould, or mixed with the sand that forms the mould, to give the casting a fine and smooth surface.
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In arithmetic, the factor is the multiplier and multiplicand, from the multiplication of which proceeds the product; thus 7 and 4 are the factors of 28 (28 equals 7 multiplied by four). In algebra any expression which is considered as part of a product is considered a factor.
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Faeces is the term applied to egested food.
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Fahrenheit is a now mainly obsolete scale of temperature. It was invented by Gabriel Fahrenheit and used in the graduation of his thermometer. The Fahrenheit thermometer is so graduated that the freezing point of water is at 32 degrees above the zero of its scale, and the boiling point is at 212 degrees above.
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Fail soft is a computer term for the ability to fail with the minimum destruction or minimising potential damage.
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Faints is the name given to the impure spirit which comes over first and last in distillation.
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All bodies on the earth, by virtue of the attraction of gravitation, tend to the centre of the earth. A ball held in the hand presses downward; if dropped, it descends perpendicularly; if placed on an inclined plane, it rolls down, in doing which it presses the plane with a part of its weight. In the air bodies fall with unequal velocities, a piece of paper, for instance, more slowly than a ball of lead; and it was formerly thought that the velocity of the fall of bodies was in proportion to their weight.
This error was attacked by Galileo, who, experimenting with balls of different substances which he dropped from the tower of Pisa, was led to the conclusion that the resistance of the air acting on different extents of surface was the cause of the unequal velocities, and that in a vacuum all bodies would fall with the same velocity. The truth of this last proposition wag first demonstrated by Isaac Newton in his celebrated 'guinea-and-feather' experiment, where a guinea and feather are shown to fall side by side in the vacuum of the air-pump. This experiment proves that the force of gravitation in bodies is proportional to their inertia, that is to their mass. The laws of falling bodies, that is of bodies falling freely in a straight line and through a distance short in comparison with the earth's centre, are the following:
1. When a body falls from rest it acquires velocity at the rate of about 32.2 feet per second. This number, which represents the acceleration due to the force of gravity, varies slightly with the locality, increasing from the equator to the poles, and diminishing as we recede from the centre of the earth. At the end of five seconds, therefore, the body would be found to be moving at the rate of 5 x 32.2, that is 161 feet per second.
2. The space fallen through in the first second is half of 32.2, that is 16.1 feet; and the space fallen through in any given time is found by multiplying the square of the number of seconds by 16.1. Thus, in three seconds a body falls 9 x 16.1 feet, or 144.9 feet.
3. The square of the velocity acquired by falling through any number of feet is found by multiplying twice that number by 32.2. Thus if a body falls 9 feet, the square of the velocity acquired is 2 x 32 x 9, or 576 feet per second, 32 being used instead of 32.2; and taking the square root of 576, we find that a velocity of 24 feet is acquired in a fall of 9 feet.
4. When a body is projected vertically upward with a given velocity, it continues to rise during a number of seconds found by dividing the number that expresses the velocity of projection by 32.2; and it rises to a height found by dividing the square of that number by 2 x 32.2, or 64.4.
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The farad is the unit of measurement of electrical capacitance. A capacitor has a capacitance of one farad if a quantity of one coulomb has to be imparted to it in order to raise the potential difference between the plates by one volt. More convenient units for small capacitances are the microfarad and the picofarad.
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The Faraday cage is an earthed metallic wire or gauze screen enclosing electrical equipment to shield it from the influence of external electric fields. The principle, put forward by Michael Faraday, is that within a conductor there is no charge, and this has been proved correct. The principle is used to make metal jump suits to be worn by electrical engineers working on high tension electricity cables.
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A Faraday screen is an earthed wire screen placed in an equipment so as to prevent electrostatic but not electromagnetic coupling between components.
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A fatty acid is an organic hydrocarbon with a carboxyl group at one end. Fatty acids are obtained by the hydrolosis of fats.
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A faucet is a form of valve or cock in which a spigot or plug opens or closes a part of a pipe for the passage of liquid.
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Fehling's Solution is a laboratory reagent consisting of a solution containing copper sulphate, caustic soda and a double tartrate of potassium and sodium (Rochelle salt). Fehling's solution is used in the laboratory as a method for the quantitative examination of sugars.
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Fermentation is the biochemical decomposition of sugars into alcohol by the action of yeast, resulting in effervescence and the evolution of heat.
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Fermium is a man made, radioactive metal element with the symbol Fm. It is named after Enrico Fermi.
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Ferrel's Law is a meteorological generalisation propounded around 1900 by the American, Professor Ferrel that the deflecting force exerted on the winds of the globe by the earth's rotation is inversely proportionate to the velocity of motion, increasing from zero at the equator to a maximum value at either pole. This force deflects the winds in the northern hemisphere to the right and the southern hemisphere to the left.
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A ferrite-rod aerial is a receiving aerial consisting of a small coil mounted on a short rod of magnetic ferrite. The coil is, in effect, a small frame aerial, and the function of the ferrite rod is to concentrate the magnetic flux from a large area surrounding the aerial. Like all frame aerials the ferrite-rod aerial has pronounced directional properties. Its main advantage however lies in its compact dimensions.
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Ferrites are a class of chemical compounds having the general formulae MFe2O4, where M is a divalent metal. Certain of these compounds are ferromagnetic, and possess in addition other properties which render them valuable for use in electric circuit components operating at high frequencies.
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A ferro-ceramic bead is a short tube of about 3 mm length and diameter of some 3.5 mm, constructed of ferro-ceramic material. They are used in radio and television to increase the inductance and high-frequency resistance of the wire upon which they are threaded, without affecting DC resistance.
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Ferrochrome is various alloys of iron and chromium employed in the manufacture of steel.
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Ferromagnetic is a term applied to materials such as iron, cobalt, nickel and certain alloys, which have a magnetic permeability very much greater than unity and which varies with the strength of the applied field.
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Ferrous is a chemistry term referring to materials which contain iron.
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The Fibonacci sequence or Fibonacci series is the infinite sequence of numbers, 0, 1, 1, 2, 3, 5, 8, etc., in which each member - known as a Fibonacci number - is the sum of the previous two numbers. The series is named after the Italian mathematician Leonardo Fibonacci.
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Fibre Optics is a technology using light as a digital information bearer. Fibre optic cables ( light guides ) are a direct replacement for conventional wire, coaxial cable and many forms of radio, including microwave. Fibre optic lines actually cost less, occupy less space and provided far more transmission capacity than earlier methods, while providing superior quality due to virtual immunity to electrical interference.
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Fibroin (Fibrosin) is a tough, elastic, albuminoid protein which forms over 50 percent of silk and spider's web.
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FidoNet is a world-wide hobbyist network of personal computers which exchange mail, discussion groups, and files. It was founded in 1984 and originally consisting only of IBM PCs and compatibles,
FidoNet now includes such diverse machines as Apple IIs, Ataris, Amigas, and UNIX systems.
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A file is a bar of cast-steel with small sharp-edged elevations on its surface called teeth, the use of which is to cut into or abrade metals, wood, ivory, horn, plastic etc.
Files are of various shapes, as flat, half-round, three-sided, square, or round, and are generally thickest in the middle, while their teeth are of various degrees of fineness and of different forms. A file whose teeth are in parallel ridges only is called single-cut or float-cut. Such are mostly used for brass and copper.
When there are two series of ridges crossing each other the file is double-cut, which is the file best suited for iron and steel.
Rasps are files which have isolated sharp teeth separated by comparatively wide spaces, and are used chiefly for soft materials such as wood, plastic and horn.
Each of these three classes of files is traditionally made in six different degrees of fineness, the coarsest being called rough, the next middle, followed by bastard, second-cut, smooth, and superfine or deadsmooth, each a degree finer than that which precedes it. Files were formerly made by the hand, The bionics, as the steel before it has teeth is called, were laid on the anvil and struck with the chisel, which rested obliquely on the blank, each blow raising a ridge or tooth. The strength of the blow depended on the hardness of the metal, and when one part is harder than another the workman altered his blows accordingly. When one side is covered with single cuts, if the file was to be double cut he added in the same manner a second series, crossing the others at a certain angle. In making fine files a good file-cutter would cut upwards of two hundred teeth within the space of an inch. The files, except those that are used for soft substances, were then hardened by heating them to a cherry-red colour and then dipping them in water. They were then finished by scouring and rubbing over with olive-oil and turpentine.
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FileMaker II by Claris, was a database publishing tool that combined file management and form generation to give impressive visual impact. FileMaker II supported full font and size control and line and box drawing. It was a good product for generating business forms and was compatible with Macintosh networks such as ApphShare and TOPS. FileMaker II could be used to create and run scripts for automating repetitive jobs such as printing mailing labels and performing searches. Although FileMaker II was not considered a relational database, its look-up function gave it some relational attributes that let users copy data from other files when the key fields matched. Even though
FileMaker II stored all the working records on disk and not in RAM, it searched database files quickly because each word was automatically indexed. Picture fields were not indexed. Indexes enhance the speed of searches only not sorts, so large data fits took some time to complete their sorts.
FileMaker II let you generate professional-quality reports and forms using an interface similar to MacDraw.
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Filtration is the process of freeing a liquid from solid matter suspended in it by causing it to pass through some pervious substance or substances which catch and retain the solid matter, The materials of which a filter is composed must have pores or interstices sufficiently coarse to allow the passage of the liquid, and yet sufficiently fine to prevent the passage of any solid particles. On a small scale unsized paper is often used; on a large scale various kinds of stone, sand, gravel, powdered glass, clay, charcoal, coke, etc, are traditionally employed. In domestic filters the simplest forms are those in which the water passes down by gravity through the filtering medium to a reservoir below. Lateral and ascending filters are not uncommon.
Filtration can be hastened by applying suction or pressure. The latter method is used in the Pasteur-Chamberland filter, consisting of a hollow cylinder of porous porcelain, which can be attached to an ordinary water-tap, the water being thus forced through the pores. The filters at water-works are large tanks or beds, filled with layers of large stones, pebbles, coarse gravel, fine gravel, coarse sand and fine sand - the fine sand being at the top. Other materials are sometimes utilized, such as furnace cinders or clinkers, shells or shell-sand, and so forth. The water in the reservoir, collected from springs, streams, and rain, is allowed to deposit its suspended matter in settling-tanks, and then it is run into the filters. By percolation the rest of the mineral matter is removed, and the water then flows into the pipes which are to convey it to the locality where it is to be used. Filtration can only remove substances mechanically suspended, for dissolved substances distillation is necessary.
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Fine Reader 4 is an optical character recognition program by Abby Software for the PC running Windows 95 and Windows NT. Unlike other OCR systems it is very tolerant of different fonts and has a very high success rate in recognising text from a wide variety of printed sources, not just modern texts produced using standard fonts.
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Finger is a computer program that displays a particular user or all users logged on the system or a remote system. Typically it shows the full name, last login time, idle time, terminal line, and terminal location (where applicable). Because most Finger installations support redirection to another terminal, for example: $finger @systemtwo.com@systemone.com It can be used for denial of service attacks on network servers. The redirection serves both to hide the terminal originating the finger request, and can be used to generate repeated finger requests to a host computer, using up memory and bandwidth.
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Fire is the rapid liberation of heat by the chemical combination of various substances with the oxygen of the air, a process known as combustion.
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A fire extinguisher is an apparatus for putting out fires. The first, the 'fire-annihilator' was invented by Philips in 1849. It was an apparatus which produced steam and carbonic acid, which extinguished flames, however it was not a commercial success. In 1862 Carlier invented L'Extincteur which was patented in 1862 by Vignon. It was an iron cylinder filled with water and carbonic acid gas, generated by bicarbonate of soda and tartaric acid. This device was further improved by Dick and a model patented in 1869.
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The fire point is the temperature at which a substance will ignite and continue to burn when brought into contact with a small flame.
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A Fire-alarm is an apparatus used for detecting fires, and for giving instantaneous notice of an outbreak. As early as 1900 detectors were often placed in the different apartments of a building, which rang an alarm when the temperature reached a certain height. During the Victorian period in Britain large towns had a series of signal-boxes distributed in different quarters from which an alarm could be immediately telegraphed to the fire-brigade station.
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In steam engines, a fire-box was the box (generally made of copper) in which the fire in a locomotive engine was placed.
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Firedamp is the name given by miners to the explosive mixture of the hydrocarbon methane with air, which sometimes occurs in coal-mines.
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In computing, a firewall is a system that is set up to control traffic flow between two networks.
Firewalls are most commonly specially configured Unix systems, but firewalls have also been built out of many other systems, including systems designed specifically for use as firewalls. The most common firewall today is CheckPoint FireWall-1, but competitions such as Cisco's PIX are quickly catching up on CheckPoint. One type of firewall is the packet filtering
firewall. In a packet filtering firewall, the firewall examines five characteristics of a packet: Source IP address Source port Destination IP address Destination port IP protocol (TCP or UDP) Based upon rules configured into the firewall, the packet will either be allowed through, rejected, or dropped. If the firewall rejects the packet, it sends a message back to the sender letting him know that the packet was rejected. If the packet was dropped, the firewall simply does not respond to the packet. The sender must wait for the communications to time out. Dropping packets instead of rejecting them greatly increases the time required to scan your network. Packet filtering
firewalls operate on Layer 3 of the OSI model, the Network Layer.
Routers are a very common form of packet filtering firewall. An improved form of the packet filtering firewall is a packet filtering firewall with a stateful inspection engine. With this enhancement, the firewall 'remembers' conversations between systems. It is then necessary to fully examine only the first packet of a conversation.
Another type of firewall is the application-proxy firewall. In a proxying firewall, every packet is stopped at the firewall. The packet is then examined and compared to the rules configured into the firewall. If the packet passes the examinations, it is re-created and sent out. Because each packet is destroyed and re-created, there is a potential that an application-proxy firewall can prevent unknown attacks based upon weaknesses in the TCP/IP protocol suite that would not be prevented by a packet filtering firewall. The drawback is that a separate application-proxy must be written for each application type being proxied. You need an HTTP proxy for web traffic, an FTP proxy for file transfers, a Gopher proxy for Gopher traffic, etc. Application-proxy firewalls operate on Layer 7 of the OSI model, the Application Layer. Application-gateway firewalls also operate on Layer 7 of the OSI model. Application-gateway firewalls exist for only a few network applications.
A typical application-gateway firewall is a system where you must telnet to one system in order telnet again to a system outside of the network. Another type of application-proxy firewall are SOCKS firewalls. Where normal application-proxy firewalls do not require modifications to network clients, SOCKS firewalls requires specially modified network clients. This means you have to modify every system on your internal network which needs to communicate with the external network. On a Windows or OS/2 system, this can be as easy as swapping a few DLL's.
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A fish-joint is a splice or joining, as in railway lines, where two rails end to end are fastened together by flat pieces of iron or steel (known as fish-plates) placed on each side of the rails, and fastened by screw-nuts and bolts (known as fish-bolts). Fish-joints allow the joined materials to expand and contract with the ambient temperature without buckling and breaking, the joint sliding as the pieces expand and contract.
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In chemistry, fission is the disintegration of the nucleus of a heavy atom with the liberation of large amounts of energy.
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Flake white is an artists' pigment produced from fine quality white lead by precipitation.
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Flamboyant finish is a form of industrial paintwork, popular for bicycle frames, whereby the article to be painted is given one or two coats of metallic paint, usually aluminium, before being lightly sprayed with a coat of semi-transparent very pure brilliant colour and finished with a coat of clear lacquer.
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A flame is a blaze rising from a burning body, or any inflammable gas in a state of visible combustion. Flame is attended with great heat, and sometimes with the evolution of much light; but the temperature may be intense when the light is feeble, as is the case with the flame of burning hydrogen gas. The flame of a candle may be divided into three zones: an inner zone containing chiefly unburned gas, another zone containing partially-burned gas, and an outer zone where the gas is completely consumed by combination with the oxygen of the air. The luminosity of flame depends upon the presence of extremely small particles of solid matter (usually carbon) or of dense gaseous products of combustion. When the pressure of the gas producing the flame is so great that it is all but flaring, it is found that certain sounds will cause the flame to alter its shape, thus producing the phenomenon of sensitive flames.
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A flange is a projecting edge, rim, or rib on any object, as for example the rims by which cast-iron pipes were connected together, or the projecting pieces on the wheels of railway carriages to keep them on the rails.
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Flash is a vector type animation format made by Macromedia and created using Macromedia applications, such as Director and Fireworks. Compared to most other types of animated images or film clips, Flash objects have a relatively small file size, because they are based on vector graphics and are popular because they take less time to download, however the user must have a Flash plug-in installed in order to view a Flash file.
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The flashpoint is the temperature at which a material gives off a vapour which will ignite upon exposure to a naked flame.
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Flint-glass is a species of glass, so called because pulverized flints were originally employed in its manufacture. It was extensively used for domestic purposes. Its dispersive power in regard to light renders it invaluable in the manufacture of the object-glasses of telescopes and microscopes, as by combining a concave lens of flint-glass with one or two convex lenses of crown-glass, which possesses much less dispersive power, a compound lens is formed in which the prismatic colours arising from simple refraction are destroyed, and the lens rendered achromatic. Quartz and fine sand were later substituted for flint in the manufacture of this glass.
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In computing, a flip-flop is a one-bit memory element. More fully, a flip-flop is an electronic circuit element capable of exhibiting either of two stable states and of switching between them in a reproducible manner.
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A floorboard saw is a light hand saw characterised by having teeth running round to the back edge of the blade, and designed for cutting floorboards in situ.
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A Florence flask is a round bottle with a flat bottom and a long neck used in laboratories.
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Flour paste, comprising just wheat flour and water, is an adhesive formerly much used for hanging wallpaper.
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Flowers was formerly a chemical name for fine particles of bodies in the form of a powder or mealy substance, for example flowers of sulphur, etc.
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A fluid is a body whose particles on the slightest pressure move and change their relative position without separation; that is a liquid or a gas, as opposed to a solid. Fluids are divided into liquids, such as water and bodies in the form of water; and gaseous bodies or aeriform fluids. Liquids have been also termed non-elastic fluids, for although they are not altogether void of elasticity, they possess it only in a small degree. Air and aeriform bodies have been called elastic fluids on account of their great elasticity.
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Fluorescein is an organic dye compound obtained by heating together pthalic anhydride and resorcinol. It is a red powder insoluble in water, but it dissolves in alcohol and also in alkalis, giving a brilliant green fluorescence.
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Fluorescence is the process of emission of electromagnetic radiation resulting from the absorption of certain types of energy. Fluorescent paints are usually the sulphides of calcium, barium and strontium which glow in the dark after having been exposed to light for a while.
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Fluorides are the metalic salts of hydrofluoric acid. Calcium fluoride and cryolite are the most common fluorides, and occur naturally. Othe fluorides are prepared artificially by neutralizing the hydrofluoric acid with metallic hydroxides or carbonates. The term 'flouride' used in popular language refers to sodium flouride, which is controversially added to drinking water supposedly to help strengthen tooth enamel against decay.
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Fluorine is a very poisonous greenish-yellow gaseous element with the symbol F belonging to the group known as the halogens. It is the most chemically reactive element (many substances ignite spontaneously in it), and for this reason it is never found uncombined. Fluorine was isolated in 1886 by Moissan by the electrolysis of a solution of potassic fluoride in hydrofluoric acid. Fluorine has also been detected in the bones, teeth, blood, milk, and urine; in plants; in volcanic sublimates;
in rocks; in coprolites and mineral phosphates and in a variety of minerals.
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A fluorocarbon is a compound in which hydrogen atoms of a hydrocarbon have been replaced with fluorine.
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A flux is a substance or mixture added to assist the fusion of minerals. In the large way, limestone and fluorite are used as fluxes. In the smelting of iron the flux must be such that it will combine with the earthy matter of the ore, and form a slag, which must neither be too refractory nor fusible. The fluxes made use of in assays or chemical experiments consist usually of alkalies and alkaline salts, as borax, potassium cyanide, potassium carbonate, sodium carbonate, common salt, which render the earthy mixtures fusible by converting them into glass. The fluxes used in pottery are various, but almost all consist of litharge or red-lead, borax, carbonates of potassium and sodium, and sand. In soldering, a flux is a substance used to keep the surfaces which have to be soldered together clean, by reducing any oxides which may form to the metallic state.
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In mathematics fluxions is the analysis of infinitely small variable quantities, an old method of calculation first invented by Isaac Newton, which does not essentially differ from that employed in the differential calculus invented by Leibnitz, except in the notation. Newton's notation was adhered to by English writers up to the early part of the present century, but the differential calculus is now universally employed.
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A fly-wheel is a heavy wheel whose inertia maintains a nearly uniform speed of rotation under variable load or driving force, and is thus used for the purpose of rendering the motion equable and regular by means of its momentum. The revolving fly-wheel is a reservoir of energy by virtue of its movement of inertia, and its effectiveness depends on the amount of energy which it absorbs or gives up for a given change of speed.
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The Flying Teapot was a British Bulletin Board System (BBS) specialising in the distribution of pirated software (warez) during the early 1990s.
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In optics, the focus is a point in which any number of rays of light meet after being reflected or refracted by a mirror or a lens.
In geometry, the focus is an important point on the principal axis of the parabola, ellipse, and hyperbola. The ellipse and hyperbola have each two foci, the parabola one, though in the latter case we may suppose a second focus at an infinite distance. The foci were so called from the fact that rays of light proceeding from one focus and reflected from a corresponding reflecting surf ace pass through the other focus.
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Fog is a cloud at or near the surface of the earth, produced by the condensation of the invisible vapour of the atmosphere into minute watery particles, this condensation being caused by a cold current of air, or the contiguity of a cold surface. Fogs are more frequent in those seasons of the year when there is a considerable difference of temperature in the different parts of the day. In low, moist places, and in confined places, as valleys, bays, or lakes, surrounded by high lands, they are much more prevalent than in open countries or elevated spots, where they are quickly dispersed by the winds. The former disagreeable pungency of fogs in large towns - the infamous London smog - was due to the presence of smoke and other impurities.
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In metallurgy, foil is a term for a thin sheet of metal intermediate between a leaf, such as gold leaf, and sheet metal. It varies in thickness according to the constituent metal or metals. Very thin tin foil is used for backing mirrors, and in chemistry and electronics.
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A folded dipole is a dipole aerial consisting of two conductors in parallel, only one of which is broken at the centre for connection to the feeder. This construction increases the bandwidth and the centre impedance of the aerial.
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Folic acid is a B vitamin essential for growth, and plays many other roles in the body. A lack of
folic acid causes anaemia because it is necessary for the synthesis of nucleic acids and the formation of red blood cells.
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In computing, a font is a specific typeface and type size. Thus, Arial (typeface) 12 point (type size) describes a font, and Arial 10 point describes a separate font. The term is widely mis-used as a replacement for 'typeface'.
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In computing, footprint refers to the floor or desk area taken up by a piece of hardware.
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In computing, foreground describes a process or program which is currently executing, and which you must wait to finish before you can issue other commands.
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A forestaff was an instrument formerly used at sea for taking the altitude of heavenly bodies.
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A forge is a blacksmith's fireplace or furnace for melting and refining metal.
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Formaldehyde (methyl aldehyde) is the simplest representative of the aldehydes. It has the formula H. CHO, and is a colourless and very pungent gas. It is very soluble in water. It has a powerful preserving effect and is used in aqueous solution for preserving anatomical specimens.
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Formalin is an aqueous solution of formaldehyde (40 percent) and often 15 percent methyl alcohol. It is used as a disinfectant and as a preservative.
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There are many theories as to how the solar system formed. And it is generally accepted that any theory of the formation of the solar system must explain at least the following two observations: First, the planets, with the exception of Pluto, orbit in almost the same plane (the 'ecliptic'). Second, the inner four planets are small and rocky, while the outer four planets are large and gaseous. One theory that does a reasonably good job of explaining these observations is the disk model.
The Sun is thought to have formed by the collapse of a large interstellar gas cloud. The original cloud was probably thousands of times larger than the present solar system. Initially the cloud had a very slow rotation rate (it's essentially impossible for one of these clouds to have a rotation rate of exactly zero). As it collapsed, it began rotating faster. The collapse process is not 100% efficient, though, so some of the material did not fall into the proto-Sun. This rotating gas that was left behind settled into a disk. In addition to gas, interstellar clouds can also contain dust. Therefore, the rotating disk consisted of dust grains and gas. In the process of settling into a disk-and even after the disk had formed-the dust grains began to collide and stick together. Initially quite small, this process of colliding dust grains sticking together (known as ' accretion') began to build up larger dust grains. The accretion process continued with large dust grains accreting to form small pebbles, small pebbles accreting to form large pebbles, pebbles forming rocks, rocks forming boulders, etc. Initially this process is quite random: Two dust grains collide only if their paths happen to cross. However, as particles became larger, they exert a larger gravitational force and attract smaller particles to them. Hence, once started, the accretion process can actually speed up.
The collapse process itself can generate considerable heat. Furthermore, as the Sun's mass grew, it eventually reached the point at which fusion reactions in its core could be sustained. The result was that there was a heat source in the middle of the disk: the inner parts of the disk were warmer than the outer parts. In the inner part of the disk, only those materials which can remain solid at high temperatures could form the planets. That is, the dust grains were composed of materials such as silicon, iron, nickel, and the like; as these materials accrete they form rocks. Farther from the early Sun, where the disk was cooler, there were not only dust grains but also snowflakes (primarily ice flakes of water, methane, and ammonia). In the outer parts of the disk, not only could dust grains accrete to form rocks, but these snowflakes could accrete to form snowballs. Water, methane, and ammonia are relatively abundant substances, particularly compared to substances formed from silicon, iron, etc.
In the inner part of the solar system, where only rocks could remain solid, we therefore expect small planets, whereas in the outer solar system, where both rocks and ices could remain solid, we therefore expect large planets. (Not only did the gaseous planets form from more abundant substances, they also had more raw material from which to form). It is currently thought that the giant planets, particularly Jupiter and Saturn, formed from a run-away accretion process. They started accreting slowly and probably initially were quite rocky. However, once their mass reached about 10 to 15 times that of Earth, their gravitational force was so strong that they could attract not only other rocks and snowballs around them, but also some of the gas in the disk that had not frozen into an ice. As they attracted more material, their gravitational force increased, thereby attracting even more material and increasing their gravitational force even more. The result was run-away accretion and large planets. One of the problems with this theory for the formation of Jupiter, though, is that it seems to take longer than the disk may have existed. The conventional scenario predicts that Jupiter might have taken several million years to form.
Other theories indicate that a giant planet might also form from small, unstable clumps in the disk. Rather than being 'bottom-up'. One of the results of finding planets around other stars is the realization that this model does not require the planets to always have been in the same orbits as they have today. Interactions between the planets, particularly the giant planets, and the disk of material could have resulted from migration. The giant planets may have moved inward or outward from their current locations during their formation. If planets can migrate during or shortly after their formation, it makes it easier to explain the presence of Uranus and Neptune. A straightforward application of the above model encounters a slightly embarrassing problem: The time to form Uranus and Neptune is longer than the age of the solar system. If, however, these planets formed at a closer distance, then migrated outward, it may be easier to understand why Uranus and Neptune are at their current distances from the Sun.
Research Formation of The Solar System
Formic acid is the lowest member of the fatty acids. It has the formula H.COOH and is found in nature in ants, stinging nettles, and in various parts of the animal body. Commercially it is used in tanning and electro-plating. It was originally extracted from crushed ants, before artificial production was developed by Pelouze in 1831.
Research Formic Acid
FormTool by Bloc development is a computer forms editor that lets users create forms such as time sheets, expense reports, or activity logs. FormTool can draw vertical and horizontal lines, boxes, and grids. One keystroke can create page-wide lines or change a line into a double line. A drag mode lets you position blocks and copy or move them within or between forms using the windowing facility. FormTool can extract data from dBase, DIF, and ASCII files to merge into template forms. You can also create a form, fill it in on the screen, and print the form and data together. The on- screen data entry capabilities are limited, however. FormTool includes a forms database to sort and organise forms. Information about the forms includes date created, form name, and degree of complexity. A unique quick view lets you see forms before selecting them. The product works with standard-width paper sizes and lets you customise for odd sizes up to a width of 13.2 inches and a height of 13.3 inches. An automatic form sizer determines form size based on
file size; this is a particularly useful feature when using the file importing utility.
Research FormTool
A formula is a fixed form of words or symbols. In mathematics it is a general theorem, a rule or principle expressed in algebraic symbols. In chemistry a formula is a mode of expressing the composition of a compound by means of symbols and letters.
Research Formula
Formulin is a mixture of 67% methanol and 33% formaldehyde used as to preserve specimens and as a fumigant. It causes vertigo, anxiety and panic attacks if consumed.
Research Formulin
Fortin's barometer was a form of barometer, similar to the cistern barometer, but the base of the cistern was made of leather, and could be raised or depressed by means of a screw; a constant level of the mercury from which to measure the zero of the scale thus being possible, which is wasn't with the cistern barometer.
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A foundry is a factory where casting (founding) takes place.
Research Foundry
Foxbase+ is a developmental tool based on the dBase data structure and programming language. Foxbase+ creates files with a .FOX extension which must be run with either Foxbase+ Development or Foxbase+ Runtime. A runtime version is necessary to distribute programs to other users. Under the runtime version, Foxbase+ programs may be executed but not modified. The runtime version ensures the integrity of source code by only allowing users with the development program access to the source code.
Foxbase+ includes an interpreter similar to dBase from which you can run
Foxbase+ programs or any uncompiled dBase III Plus program. In fact, you can run almost any dBase III Plus command from the Foxbase+ dot prompt without worrying about incompatibility. The Product's Assistant is similar to that in dBase III Plus. Foxbase+ has many features that make it easy to use, such as the FoxCentral interface, which allows novice users to take advantage of Foxbase+'s features. A screen and code generator is also included.
Research Foxbase+
FoxPro is the PC version of FoxBASE+/Mac. It is a relational database with a report generator, application generator, and screen painter. Although it is a character-based product, it has some features of a graphical interface: pull-down and pop-up menus, buttons, check boxes, and scroll bars. FoxPro can be used for simple data entry, query and report applications, or complex menu- driven user applications. For less experienced users, it offers an easy-to-use, mouse-driven interface; for developers, it offers an interactive syntactical mode. There are step-by-step tutorials geared to four levels of experience. Most functions run in their own window. Colours can be assigned to any screen area. Applications created in Foxbase+ and dBase III Plus are fully supported.
Research FoxPro
In arithmetic and algebra, a fraction is a combination of numbers representing one or more parts of a unit or integer: thus, four-fifths (4/5) is a fraction formed by dividing a unit into five equal parts, and taking one part four times.
Fractious are divided into vulgar and decimal. Vulgar fractions are expressed by two numbers, one above another, with a line between them. The lower, the denominator, indicates into how many equal parts the unit is divided; and the number above the line, called the numerator, indicates how many of such parts are taken.
A proper fraction is one whose numerator is less than its denominator. An improper fraction is one whose numerator is not less than its denominator, as (8/5).
A simple fraction expresses one or more of the equal parts into which the unit is divided, without reference to any other fraction.
A compound, fraction expresses one or more of the equal parts into which another fraction or a mixed number is divided. Compound fractions have the word of interposed between the simple fractions of which they are composed: thus 1/3 of 4/5 of 1 4/7is a compound fraction.
A complex fraction is that which has a fraction either in its numerator or denominator, or in each of them.
In decimal fractions the denominator is 10, or some number produced by the continued multiplication of 10 as a factor, such as 100, 1000, etc; hence, there is no necessity for writing the denominator, and the fraction is usually expressed by putting a point (•) before the numerator, as 0.5 - 5/10. All calculations are much simplified in decimal fractions; yet, simple as the system is, it was only discovered first in the 15th century by the German mathematician Regiomontanus.
Research Fraction
In computing, a framebuffer is a memory projection of a video card's RAM into main memory. This allows applications to access the video RAM without communicating directly to the video card, which is a slower process.
Research Framebuffer
Ashton-Tate's Framework is a decision support tool designed to help you organise and analyse all the information encountered in the daily work environment. Framework III contains a spreadsheet, database, word processor with outlining, graphics, and communications with electronic mail. By combining all the software tools typically needed, Framework III lets the user switch from one function or one project to another without changing disks or leaving the program. The word processing module in Framework III is the central feature of this product. It includes an 80,000- word spell checker and a thesaurus; foreign language disks are available for each of these features. You can generate tables of contents, footnote documents, and see formatting such as bold, italics, subscript, and superscript onscreen.
Framework III's extremely powerful outlining capability makes the product a perfect choice for professionals who often need to organise and re-organise lengthy documents into many sections with subheadings and titles. Documents can include spreadsheet and database information as well as graphics. Electronic mail capabilities are integrated into Framework III's pull-down menus.
Framework III users can communicate with each other or users of other compatible network mail programs. The electronic mail feature uses the MHS (Message Handling Service) format.
Research Framework
Franckincense is a gum resin obtained from trees of the genus Boswellia, used in the making of incense and in ancient times in medicine.
Research Franckincense
Frangulin is a yellow crystallisable dye extracted from the bark of the alder. It is used to dye wool, silk and cotton.
Research Frangulin
The Franklin aerial is a directional aerial consisting of a number of radiating elements, uniformly spaced on a line at right angles to the desired direction of maximum radiation.
Research Franklin Aerial
A Franklin stove is a cast-iron room-heating stove in the manner of a fireplace, but being enclosed on all sides except the front which is either open or fitted with doors which may be opened or closed. Franklin stoves were designed by the 19th century American inventor Benjamin Franklin.
Research Franklin Stove
Free MP3 by Axis Soft is a nice, little MP3-player for the Windows operating system which plays any MP3-file. All mpeg-audio formats are supported, including variable bitrate (Xing alike). You can add your tracks to a play list and arrange the tracks in the play list in any way you like. The play list is Winamp compatible, so you can also use already generated lists. You can add and edit the description of a track (ID3 support). The looks and feel of the player can be changed with skins. A spectrum analyser completes this nice looking MP3-player.
Research Free MP3
Free web hosting is the idea that a company will host your web site on their computer without you making a payment to them. These companies make their money in one of three ways. The most common is to add an advertising banner to the pages of your web site hosted for free, the advertising revenue then goes to the hosting company. A second way, popular in the UK, is for telephone companies to provide free web space providing you access the internet via them. They receive revenue from the cost of your dial-up connection. The third and final way is for web design companies who charge you to design your web site and then host it for free. Most free web hosting services are very restrictive. For example, most only offer less than 25 mB of space, they may add a banner advert to every page, you may be forbidden from carrying your own advertising. Some, however, are very flexible. They may for example provide unlimited web space and only place a single advertising banner on the 'home page', with no restrictions on the placement of your own adverts.
Research Free Web Hosting
FreeForm by Herne Data Systems Ltd formats all styles of standard DOS disks, as well as non-DOS disks, and customized DOS disks (i.e you can make up your own copy protection schemes). It gives complete control over formatting parameters such as sector size, disk density, number of sectors and tracks. It is menu driven, and includes user configurable formatting parameters.
Research FreeForm
Aldus Freehand is a comprehensive drawing program for the Mac that lets you produce high-quality graphics on PostScript output devices. It combines a wide range of drawing tools with colour support, automatic tracing for imported images, special effects, and advanced text-handling capabilities to create a variety of line-oriented illustrations including technical, scientific, and architectural illustrations. Its curve-handling capabilities and colour support provide flexibility for more sophisticated illustration. Freehand has strong text manipulation capabilities. Each block of text is considered an element and can be rotated, mirrored, skewed, and resized.
Research Freehand
In computing, freeware refers to free software, often written by enthusiasts and distributed by users' groups, or via electronic mail, local bulletin boards, USENET, or other electronic media. At one time, 'freeware' was a trademark of Andrew Fluegelman, the author of the well-known MS-DOS communications program PC-TALK III. It wasn't enforced after his mysterious disappearance and presumed death in 1984.
Research Freeware
French ochre is a good quality opaque ochre of a bright yellow colour and good staining strength.
Research French Ochre
French polish is a spirit varnish comprised of shellac dissolved in methylated spirits sometimes with other spirit-soluble gums added, used for giving a smooth surface-coating to furniture and cabinet-work. These varnishes are sometimes coloured to modify the character of the wood. A reddish tinge is imparted by dragon's-blood or red sanders-wood, and a yellowish tinge by gamboge or turmeric-root.
Research French Polish
Frequency drift is a phenomenon which affects electronic circuits. It is variations in the natural frequency of an oscillatory circuit of an oscillator due for example, to changes of capacitance with changes of temperature.
Research Frequency Drift
Frequency modulation (FM) is a system of radio transmission in which the amplitude of the carrier remains constant but the frequency is varied in accordance with the amplitude of the modulating waveform. In frequency modulation the loudness of the applied audio-frequency modulation is represented by the amount of change of carrier frequency, and the frequency of the signal is represented by the number of times the carrier frequency is changed every second.
Research Frequency Modulation
Frequency synthesis is a tuning method in transmitters and receivers which uses a few piezoelectric crystals to generate a wide range of frequencies.
Research Frequency Synthesis
A fret saw is a long, narrow-bladed saw with the blade held tightly in a U-bend used to cut ornamental work from thin wood. A fret saw is similar to, but smaller than a coping saw.
Research Fret Saw
In physics, friction is the effect of rubbing, or the resistance which a moving body meets with from the surface on which it moves. Friction arises from the roughness of the surface of the body moved on and that of the moving body. No such thing can be found as perfect smoothness of surface in bodies. In every case there is, to a less or greater extent, a roughness or unevenness of the parts of tlie surface, arising from peculiar texture, porosity, and other causes, and therefore when two surfaces come together the prominent parts of the one fall into the cavities of the other. This tends to prevent or retard motion, for in dragging the one body over the other an exertion must be used to lift the prominences over the parts which oppose them. What is called the coefficient of friction for any two surfaces is the ratio that subsists between the force necessary to move one of these surfaces horizontally over the other, and the pressure between the two surfaces. Thus the coefficient of friction for oak and cast-iron is 38 : 100, or .38. Friction plays a most important part in nature and art; for instance, without friction threads could not be made nor textile fabrics manufactured.
Research Friction
Friction-roller is a name common to any small roller or cylinder employed to convert sliding motion into rolling motion. Such cylinders are often placed under heavy bodies when they are required to be moved any short distance on the surface of the ground; and, in machinery, the same method is occasionally employed to diminish the friction of a heavily-loaded axis. In that case a number of small cylinders are inclosed round the axis, and partake of its motion.
Research Friction-Roller
In machinery, friction-wheels are two simple wheels or cylinders intended to assist in diminishing the friction of a horizontal axis. The wheels are simply plain cylinders carried on parallel and independent axes. They are disposed so as to overlap pair and pair at each end of the main axis, which rests in the angles thus formed by the circumferences. The axis, instead of sliding on a fixed surface, as in ordinary cases, carries round the circumferences of the wheels on which it is supported with the same velocity as it possesses itself, and in consequence the friction of the system is proportionally lessened.
Research Friction-Wheel
In printing, a frisket was a light frame of the printing-press which folded down upon the tympan ober the sheet of paper to be printed. Its object was two-fold: to hold the sheet in place and to keep the margins clean.
Research Frisket
A fro or frow was a blunt edged type of wedge used for splitting wood.
Research Fro
Microsoft FrontPage is a collection of computer programs for Web site managers. It includes the
FrontPage Editor which is a WYSIWYG Web page editor, the FrontPage Explorer can show you your site in both hierarchical and graphical views and the FrontPage TCP/IP Test checks your machine for a Winsock layer, IP address, and other items needed to establish a connection to the Internet. It also includes a personal web server and server administration programs.
Research FrontPage
Fructose (fruit-sugar or laevulose) is a simple and very sweet sugar found in plant juices, fruit and honey. It is a mono-saccharose, white, crystalline compound.
Research Fructose
In geometry, the frustum is the part of a solid next to the base, left by cutting off the top portion by a plane parallel to the base; or the part of any solid between two planes, which may be either parallel or inclined to each other, as the frustum of a cone, of a pyramid, or of a sphere, which latter is any part comprised between two parallel circular sections.
Research Frustum
In Unix and Linux computer systems, fstab is a file that contains descriptive information about the various filesystems. Fstab is only ever read by programs and not written to;
Rather it is the responsibility of the system administrator to properly create and maintain the fstab file.
Research Fstab
Fsutil is a command-line utility for the Windows XP operating system that enables a system administrator to perform many FAT and NTFS file system related tasks, such as switching on and off last access time stamping, managing reparse points, managing sparse files, dismounting a volume, or extending a volume. Fsutil takes various parameters, for example: 'fsutil behavior set disablelastaccess 1' turns off the time stamping of last access dates on files, speeding up XP particularly on systems where numerous files are frequently accessed. Some of the fsutil sub commands, such as behavior, write changes to the Windows XP system registery, and as such the changes do not become active until the computer is restarted.
Research Fsutil
FTP is the user interface to the ARPAnet File Transfer Protocol. It is a computer program that allows a user to transfer files to and from a remote networked site.
Research FTP
FTP Bounce is a method of hacking or breaking into a computer network and exploits a security hole in many FTP servers that allow the FTP server to open a connection to any computer connected to it via the 'port' command, allowing the client computer access to a computer it would not otherwise be allowed to access. Using this method of attack, a hacker can log into one computer on the internet, and tell that computer (via the FTP port command) to log in to another computer on the internet. The target computer being unaware of the hacker's real computer identity or IP address. The solution, in simple terms, is to use an FTP server that does not allow connections to any computer other than the client, and to use separate computers on the network for FTP servers etc, with 'firewall' protection software between them.
Research FTP Bounce
A fugitometer is a device comprising a humidifier and an arc light which approximates to daylight. A fugitometer is used to test the effects of weathering - moisture and light - upon paint samples.
Research Fugitometer
In mechanics, a fulcrum is the support cr fixed point about which a lever turns.
Research Fulcrum
Full Duplex is a communications term referring to a circuit which allows independent transmission information in both directions simultaneously. - Synonym: In wire telephony, 4 wire circuit.
Research Full Duplex
A fulling-mill is a mill for fulling cloth by means of pestles or stampers, which beat and press it to a close or compact state, and cleanse it. The principal parts of a fulling-mill are the wheel, with its trundle, which gives motion to the tree or spindle, whose teeth communicate that motion to the pestles or stampers, which fall into troughs, wherein the cloth is put, with fuller's earth, to be scoured and thickened by this process of beating.
Research Fulling-Mill
Fulminates are the metallic salts of fulminic acid. They can be made by dissolving a metal in strong nitric acid and adding alcohol. The fulminate is then precipitated. Fulminates are highly explosive compounds used for the manufacture of detonators.
Research Fulminate
Fulmination, or explosion, is a term used in chemistry to denote the sudden decomposition of a body by heat or percussion, accompanied by a flash of light and a loud report. Small quantities of fulminating compounds or fulminates are commonly employed to detonate (or cause to explode) large quantities of other explosives, as in blasting, etc. Fulminate of mercury (a mercurt-based salt of fulminic acid) is the most common of these detonators, and forms the priming of percussion caps.
Research Fulmination
Fulminic Acid is an acid known only in the form of its salts - mercury fulminate, Hg(CNO)2, and silver fulminate, AgCNO, both of which are powerful detonators,
Research Fulminic Acid
In mathematics, a function is a quantity so connected with another that no change can be made in the latter without producing a corresponding change in the former, in which case the dependent quantity is said to be a function of the other; thus, the circumference of a circle is a function of the diameter; the area of a triangle is a function of any two of the sides and the angle they contain. In order to indicate in a general way that one quantity y is a function of another x the notation y=f(x), or something similar, is adopted.
Research Function
A funicular railway is a railway for transporting passengers up a steep incline. They often run on the principle of balance, two carriages of equal weight being joined by a long cable which passes over a pulley at the upper end. Small power is required at the pulley to bring one car up the slope while the other descends.
Research Funicular Railway
The Funnel Web Analyzer by Quest Software is a freeware computer program for the Windows, Mac OS X, Linux and Solaris operating systems that provides analysis of http server log files. The Funnel Web Analyzer provides details of visitor demographics including geographical data based upon domain name, search engine terms used to find the web site and similar reports which may be formatted in HTML, PDF and plain text formats. Funnel Web Analyzer supports incremental analysis so that subsequent analysis can be combined with earlier results and new combined reports produced.
Research Funnel Web Analyzer
a fuse is a slow burning cord or other mechanism for delaying igniting a charge, such as a mine. Early fuses (slow-matches) were made of lightly twisted hemp dipped in potassium nitrate and ignited. Modern fuses may be electrical attached to a timer, or chemical in which an acid burns away a division in a container holding two chemicals which ignite when combined.
Research Fuse
A fusee is the cone or conical part of a mechanical watch or clock, around which is wound the chain or cord. It is a mechanical contrivance for equalizing the power of the mainspring; for as the action of a spring varies with its degree of tension, the power derived from the force of a spring requires to be modified according to circumstances before it can become a proper substitute for a uniform. power. In order, therefore, to correct this irregular action of the mainspring, the fusee on which the chain or catgut acts is made somewhat conical, so that its radius at every point may be adapted to the strength of the spring.
Research Fusee
Fusel oil is the residue left after removing the ethyl alcohol from various liquors obtained by fermentation, potato spirit being the best source. Fusel oil consists principally of isoamyl and normal amyl alcohols, together with smaller amounts of butyl alcohol, and various aldehydes and esters. It is a poisonous, unpleasant smelling, oily liquid principally used as a source of amyl alcohol.
Research Fusel Oil
Fusible is a term meaning something which can be melted. Fusible metal is an alloy, usually of lead, tin, and bismuth, compounded in such definite proportions as to melt at a given low temperature. In steam-engines, a plug of fusible metal was placed in the skin of the boiler, so as to melt and allow the steam to escape when a dangerous heat is reached - thereby forming a safety fuse.
Research Fusible
Fusible porcelain is a silicate of alumina and soda obtained from cryolite and sand, fused and worked as glass.
Research Fusible Porcelain
Fusion is the conversion of a solid body into the liquid state by direct heat, as distinguished from solution, in which the effect is produced by means of a liquid. It is difficult, however, to draw a line between the two, for the main difference is in the temperature, and when a flux is employed all distinction disappears. The term is specially applied to the action of heat on the metals, but it is extended to any solid matter; thus the passage of ice into water at zero degrees Celsius is true fusion. There are bodies like carbon, lime, magnesia, zirconia, and other metallic oxides, which are practically, if not absolutely, infusible.
Research Fusion
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