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Knight's Mechanical Encyclopedia (ed. Knight), A. (search)
Remarks.) The various proportions and relative qualities as to melting-point and gravity are collected from a multitude of sources, the best attainable. The authorities, however, differ somewhat widely, and this can only be accounted for from the fact that so few metals can be obtained pure. The differences in the metals obtained from different localities are often unsuspected, and are fully proven in the variable statements of the cohesion in the tables compiled by Muschenbroek, Tredgold, Barlow, Brown, Rumford, Rennie, Telford, Bramah, and others. The difficulty that has thus arisen has caused variable statements in the formulas for bell and ordnance casting, and has very considerably affected the exactness of statement in all the alloys, especially the more fusible ones, where the various combinations of lead, tin, and bismuth give such variable results. It appears to be scarcely possible to give any sufficiently general rules, by which the properties of alloys may be safel
Knight's Mechanical Encyclopedia (ed. Knight), C. (search)
tructed by Vincenzio Galileo (the younger Galileo). A. D. 1650, Huyghens constructed clocks on this principle: — He first explained the nature, properties, and application of the pendulum, and made it perfect, except the compensation added by Graham, about 1700. Anchor pallets were introduced by Clement, in 1680, who also devised the mode of suspending the pendulum from a stud, by means of a piece of watchspring. The mechanism of repetition by means of pulling a string was invented by Barlow, 1676. The endless cord, to continue the clock in regular motion, during the time of winding up, was invented by Huyghens, 1660. This was otherwise effected by Harrison, 1735, by means of his auxiliary spring and additional ratchet. See going-wheel. Huyghens was also the contriver of the present dial-work for changing the hour into sixty minutes which divide the circumference of the dial, traversed by an additional hand in the center of the clock-face. Clocks were applied to purposes o
Knight's Mechanical Encyclopedia (ed. Knight), M. (search)
ation of all substances into magnetics and diamagnetics. A compass-needle made out of a diamagnetic would point east and west, where an ordinary compass-needle would point north and south. In telegraphy the magnets are known by their duty or their places in the circuit, as the sounding, relay, receiving magnets, etc. See electrical apparatus. Mag-net′ic Bat′ter-y. A combination of bar magnets acting together. Mag-net′ic Compen-sa′tor. An apparatus of iron plates, invented by Barlow, and placed near the binnacle for neutralizing the effect of ship's guns and other iron in deranging the bearings of the compass. It is superseded by the apparatus of Professor Airy, which consists of two magnets placed at right angles to each other below the compass, and a box of small iron chain. These are placed by experiment. See mariner's compass. Mag-net′ic guard. A respirator with a gauze of magnetic iron to arrest particles of steel dust when dry-grinding cutlery. Inven
Knight's Mechanical Encyclopedia (ed. Knight), P. (search)
ented by Leon Scott, which automatically records phonetic sounds by diagrams in a manner analogous to that in which the indicatordiagram of a steam-engine records the pressure of the steam. It proceeds upon the premises, that articulate sounds are accompanied by the expulsion of air from the mouth; that the impulses vary in pressure and duration and in the suddenness with which they commence and terminate; that different syllables vary in volume, force, continuity, and abruptness. Professor Barlow uses a speaking-trumpet about 4 inches long, having an ordinary mouth-piece connected to a tube, which has an end expansion of 2 1/2 inches diameter, which is covered with a membrane of gold-beater's skin or gutta-percha. A spring rests gently against the membrane, and carries a light arm of aluminium, which holds a small sable brush, forming a marker which touches a traveling strip of paper, registering the vibrations of the diaphragm which agree with the characteristic force, persist
Knight's Mechanical Encyclopedia (ed. Knight), R. (search)
ir (1816); the rail fastened with keys. q′, Brunton and Shield's rail and chair. r′, English rail and chair, 1840. s′, Samuel's cast-iron sleeper. t′, Barlow's rail (English). u′, tubular socketed rail. v′, Seaton's saddle-rail. w′, elastic rail. x′, Pierce's rail, on high standard. y′, Greave's pot-sleee machinery is somewhat similar to that of the alarmclock. James II., in person, heard arguments on interfering applications for patents for repeating-watches (Barlow vs. Quare), and decided in favor of Quare (1676). Priority of invention belonged, however, to Barlow, who employed two pins to strike the hours and quarters, whilBarlow, who employed two pins to strike the hours and quarters, while Quare afterward effected this with one only. The smallest repeating-watch ever known was made by Arnold for George III., to whom it was presented on his birthday, June 4, 1764. Although less than six tenths of an inch in diameter, it repeated the hours, quarters, and half-quarters, and contained the first ruby cyl
Knight's Mechanical Encyclopedia (ed. Knight), S. (search)
aily for two years, showed no signs of abrasion at the joints or elsewhere. See Railway-rail. Barlow's sleepers. Barlow's iron railway-sleeper (English) (a, Fig. 5176) is adapted for a saddle-sBarlow's iron railway-sleeper (English) (a, Fig. 5176) is adapted for a saddle-shaped rail, and rests upon iron ties or sleepers, which have seats for the rails, which are bolted thereto. Like some of the other iron devices, it was intended to preserve the permanent way against the attacks of insects in hot climates. English chairs and sleepers. Barlow's longitudinal cast-iron sleeper (b) has a central line of division and junction; to each cheek the halves of chairs materials are most frequently subjected in structures of any kind. The reader is referred to Barlow, On the strength of materials. Consult, also, Ordnance manual, ed. 1861, and technical works onge of an ordinary train, estimated to weigh 80 tons, caused a deflection of .41 foot, of which Mr. Barlow computed .182 foot was due to the elongation of the cables (a, Fig. 6093). This bridge has
Knight's Mechanical Encyclopedia (ed. Knight), T. (search)
impulses vary in quantity, pressure, and in the degree of suddenness with which they commence and terminate. An instrument which will record these impulses has been termed by its inventor, Leon Scott, a phonautograph, or phonograph, and by Mr. Barlow a logograph; the pressure of the air in speaking is directed against a membrane which vibrates and carries with it a delicate marker, which traces a line on a traveling ribbon. The excursions of the tracer are great or small from the base linetness of the rising and falling inflections, which make curves of various shapes, of even or irregular shape. The smoothness or ruggedness of a sound has thus its own graphic character, independent both of its actual intensity and its length. Barlow's logograph, described in the London Popular science Review, Vol. XIII. page 278, et seq., consists of a small speaking-trumpet. having an ordinary mouth-piece connected to a tube, the other end of which is widened out and covered with a thin m
Knight's Mechanical Encyclopedia (ed. Knight), W. (search)
ar laws. Dr. Hooke showed that the vibrations of such a spring are nearly isochronous, whatever their length, and cause the balance to which they are attached to make its excursions in equal times, although the excursions are longer when the spring is at its greatest power, when just wound up, and less in extent when the spring is nearly run down. The actual difference in the excursions is from nearly a full revolution down to about half a revolution. The repeating-witch was invented by Barlow, 1676: Quare invented a repeating movement about the same period. The drilling of jewels for the pivots was first done by Nicolas Facio, a Genevan, in 1700. The order of the jewels for hardness is as follows: diamond, sapphire, ruby, chrysolite, aqua-machine, garnet. The introduction of the main-spring, with its barrel and fuse, and the hair-spring for regulating its movement, were succeeded by other improvements, which rendered the watch, in its most perfect form, the chronometer, suff