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Knight's Mechanical Encyclopedia (ed. Knight), A. (search)
seats when attacked, and spring back again at once. The term is also applied to wagons for stores and ammunition. The Arnott stove. Ar′notts stove. The original form of Dr. Arnott's stove is shown in Fig. 364, and perhaps illustrates its pDr. Arnott's stove is shown in Fig. 364, and perhaps illustrates its peculiar principle better than do the subsequent modifications. a b d represent a box of sheet-iron, divided by the partition g h into two chambers, communicating freely at the top and bottom; e is the fire-box, formed of iron, lined with firebricked with the revolving mass. The methods of regulating the supply of air will be noticed presently. With this stove, Dr. Arnott, during the severe winter of 1836-37, was able to maintain in his library a uniform temperature of from 60° to 63°. The wood used in lighting an ordinary fire. The grate or fire-box, fully charged, held a supply for twenty-six hours. The Arnott stove. Another common form of this stove is shown in Fig. 365. A B C D is the outer casing; E the fire-box over which
Knight's Mechanical Encyclopedia (ed. Knight), B. (search)
e known several centuries ago, being made of fabric rendered air-proof by paint or varnish. The annexed cut is from the first German edition of Vegetius, A. D. 1511, and represents some soldiers reposing on one in time of war. The mode of inflation by bellows is also indicated. We see indications of the same idea in the account given of the sports of Heliogabalus, who had collapsing cushions wherewith he tricked his guests. See air-bed. See also hydrostatic bed. We are indebted to Dr. Arnott for the invention of the water-bed, which was contrived by him for the purpose of supporting the body without sensible inequality of pressure, thus preventing bed-sores. Clark, in 1813, and MacIntosh, in 1823, improved the matter by contributing a better material. The india-rubber cloth was long known simply as MacINTOSHntosh. Air-bed Bed-bot′tom. A device attached to a bedstead on which the bed immediately rests. The object to be attained is to secure sufficient strength wi
Knight's Mechanical Encyclopedia (ed. Knight), E. (search)
r-trum′pet. An instrument for the collection and conduction of sounds. By increasing the size of the auricle, a larger volume of sound is gathered than by the natural ear. The ear-trumpet for the assistance of the partially deaf is believed to have been invented by Baptista Porta about 1600. Kircher describes the funnel and tube for conveying sound, the device which is now so common for conveying intelligence between apartments and shops, in dwellings, warehouses, and factories. Dr. Arnott of England, who became partially deaf from a cold contracted in traveling, first devised the pair of shells or artificial ears which extend the surface displayed to gather the tremulous air. There are two qualities required in a speakingtube: that it shall concentrate a large amount of sound in a small space; and, secondly, that it shall not stifle the sounds within the tube itself. Guttapercha seems to answer the latter conditions better than any other material. The ear-trumpets ar
Knight's Mechanical Encyclopedia (ed. Knight), F. (search)
jambs. See coving. In 1745, Dr. Benjamin Franklin introduced a fireplace which he named the Pennsylvanian, in which Prince Rupert's descending flue was combined with Polignac's caliducts. This is shown at F. (Fig. 1997.) Count Rumford's improvements consisted mainly in the contraction of the chimney at the throat, the rounding of the breast-work, and the flaring of the covings, as illustrated in the accompanying plan and section G H. He preferred an angle of 45° for the covings. Arnott also made himself a name in this line. I J are a vertical section and plan showing an English tubular fireplace designed to warm a current of pure air derived from the outside, and direct it into the interior of a room; the air passes from the flue a to the under side of the hearth-plate b (shown in the plan), thence upward through the upright tubes at c c to a horizontal tube d (shown in the elevation), which has an opening through its entire length on the upper side, whence the hot air
Knight's Mechanical Encyclopedia (ed. Knight), H. (search)
nd then through a cellular steam-heater, where it acquires a temperature of from 75° to 85° Fah. From a brick chamber it passes by pipes to the various apartments, where it is admitted by dialed registers. See hot-air furnace; ventilation. Dr. Arnott calculated the quantity of heat-radiating surface necessary to warm a room in winter to 60° when the external temperature is 22°, to be a foot square of surface heated to 200° for every six feet of glass, as much for every 120 square feet of nnecting-rods, connecting the heads C together to resist the strain of the rams B, and forming guides for the rams. Hydro-static bed. A bag of india-rubber cloth inflated with water. Intended for bedridden or wounded persons; invented by Dr. Arnott, and described in his Elements of physics. Hydro-stat′ic Bel′lows. An instrument for illustrating the fact that the pressure of a small column of water balances that of another column of water, no matter how large. Water poured into th
Knight's Mechanical Encyclopedia (ed. Knight), M. (search)
nace had a magazine (English patent of 1785). The fire is fed from a reservoir above, and the resulting volatile products pass through the fire to the chimney. Cutler's magazine-grate was patented in England in 1815. The bottom plate of the chamber was movable, and by means of a wheel and axle the fuel contained in the chamber was raised so as to bring a new portion of fuel into the fire. The object is a full supply for a day, and a means of introducing below so as to burn the smoke. Arnott's improvement, which he termed a smokeless fireplace, is somewhat similar. Deakin's patent, 1816, had the magazine at the back of the fire, and the fuel was drawn forward horizontally by means of a screw. Alkin's English patent, 1825, resembled Deakin's. Rawe's magazine, 1854, is a fuel-pipe connecting the bottom of the grate with a side reservoir of fuel. The poker is the lever for introducing a fresh supply. Leighton, in 1856, surrounded the sides and back of the chamber wi
Knight's Mechanical Encyclopedia (ed. Knight), S. (search)
us escaping. To obviate this, and cause the smoke to pass over a mass of burning fuel, various contrivances have been invented for introducing the fresh fuel beneath that which is already burning; among these may be mentioned Cutler's; and Dr. Arnott's, which is an improvement upon it. These and others are adapted for open grates. See grate, smoke-consuming; base-burning stove. Watt, in his specification of 1785, claims constructing furnaces so that the smoke or flame of the fresh fuel by gas, the construction being agreeable thereto. See heating-apparatus; fur-Nace; and also under the various heads in the following list of stoves and heating appliances: — Andiron.Bath-furnace. Air-heater.Bath-heater. Air-stove.Battery. Arnott's stove.Blower. Asbestus-stove.Blow — up pan. Ash-pit.Boiler. Domestic Athanor.Boiler. Steam Autoclave.Boilery. Bagasse-dryer.Bone-black retort. Baker.Bookbinder's stove. Balneum.Brazier. Banking-up.Broiler. Bark-stove.Calcination. Ba
Knight's Mechanical Encyclopedia (ed. Knight), T. (search)
d with copper or other suitable material, to prevent steam from penetrating its walls and condensing inside. Thermo-met′ric Ven′ti-la-tor. A modification of Arnott's chimney-valve. It consists of a circular disk, like the throttle-valve of a steam-engine, accurately balanced on a spindle. On one side of the disk is an inven the rod and bringing the ring in contact with a claw at the short end of a bent lever communicating by a wire with the ash-pit door, which acted as a damper. Arnott's thermostat. Fig. 6370 shows a form applied by Dr. Arnott to his stove. a b is a curved tube containing mercury in the bend b: the end a is inserted in the Dr. Arnott to his stove. a b is a curved tube containing mercury in the bend b: the end a is inserted in the combustion-chamber, and as the contained air is expanded by heat, the mercury rises in the outer leg of the tube, carrying with it the fleat c, connected by a rod to the frame d, from which is suspended a wire carrying the valve f, which closes the opening of the pipe e by which air is supplied to the combustion-chamber. A fall o
Knight's Mechanical Encyclopedia (ed. Knight), U. (search)
to 2,400. Hospitals for epidemic cases5,000. The temperature in general should not exceed, for Workshops59° Fah. Hospitals61° to 64° Fah. Schools66° to 68° Fah. Meeting-rooms66° to 72° Fah. Theaters68° to 73° Fah. The air may be maintained at a higher temperature in wellventilated apartments than in those where it is not frequently renewed. Ordinarily, the fires by which the building is heated are wholly or principally relied on to effect the required renewal of the air. Dr. Arnott's plan, 1838, consists in cutting an opening in the chimney above the grate or fireplace, and providing this opening with a valve which opens inwardly to the flue, so as to draw off the foul air from the upper part of the apartment while preventing the entrance of smoke. The plan of the Marquis de Chabannes, employed at the Covent Garden Theater, 1819, consisted in using the large central chandelier as the principal ventilating-agent. This was surmounted by an inverted wrought-iron f