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Knight's Mechanical Encyclopedia (ed. Knight) 39 1 Browse Search
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d at a particular point, while the surrounding atmosphere is but little affected, as in the focus of a reflecting mirror, etc. Differential air-thermometer. Leslie, in his experiments on heat, made great use of this differential thermometer. By coloring the focal ball and leaving the other white, silvering or gilding one ofs been calculated that the nine earlier aqueducts of Rome had a total length of more than 249 miles, and the supply of water to Ancient Rome was computed by Professor Leslie, on the authority of Sextus Julius Frontinus, who was inspector of the aqueducts under the Emperor Nerva, and who has left a valuable treatise on the subjectcompanies the instrument. — Brande. At-mom′e-ter. An instrument to measure vaporous exhalations. An eraporometer or hygroscope. It was invented by Professor Leslie for determining the rate of evaporation from a humid surface in a given time. A thin ball of porous earthenware, two or three inches in diameter, with a s
s may be raised without smoking to the height of 3 1/2, 3, 2 1/2, and 2 inches respectively. The glass chimneys for the burners mentioned should be 8/10, 12/10, 13/10, 15/10 of an inch in diameter respectively. The Bude burner has two or three concentric Argand rings. The Winfield-Argand has a metallic button above the annulus to deflect the central current laterally. A contraction of the chimney above the jet has a similar effect upon the exterior envelope of air. Gas-burners. Leslie's Argand has a series of small tubes arranged in a circle, which eject the gas in a conical form just below the contraction of the chimney. Frankland's burner e is an Argand with two chimneys, the outer one standing on a plate so as to be closed at bottom, and the air passing between the two for the supply of the flame. Faraday's ventilating burner f removes the products of combustion, and prevents their mingling with the air of the apartment. It is shown in vertical and horizontal se
ed that removing the pressure of air facilitated evaporation to a degree which enabled him to freeze water even in summer. In 1777, Mr. Nairne discovered that introducing sulphuric acid into an exhausted receiver absorbed an aqueous vapor from and thereby dried rarefied air; and by an arrangement on these principles, in 1810, by which he got rid of the vapor that rose from the water, he prevented its forming a permanent atmosphere, so as to prevent the continuance of the operation. Professor Leslie succeeded in freezing quantities of water from 1 to 1 1/2 pounds in weight, though he could not effect the congelation of much larger quantities. This method of promoting evaporation John Vallance, in 1824, improved by removing the atmospheric pressure, which enabled him to carry off the vapor from large surfaces of water and consequently freeze large quantities of ice. The Parisian restaurants have decanters (carafes frappees) filled with water frozen by placing them in shallow tan
s ingenious contrivance has been rather a curiosity than a practical apparatus, as it is complicated, and requires considerable trouble in the manipulation. 7. Leslie's photometer is constructed on the assumed principle that light is convertible into heat. The differential thermometer with a black and a clear bulb is placed una hollow body assuming a convex form. Psy-chrom′e-ter. A form of hygrometer invented by August. It is on the principle suggested by Hutton, and employed by Leslie in his differential thermometer. It has two very sensitive thermometers freely suspended to the same frame. Of the two bulbs, one is wrapped with linen rags andwhen taken, is brought out by the application of a flux, and by heating the plate to a white heat is made permanent. Pyr′o-scope. An instrument, invented by Leslie, to measure the intensity of heat radiating from a hot body or the frigorific influence of a cold body. The instrument is like a differential thermometer, one ba
37BrickMar. 14, 1871. 128,517WilkinsJuly 2, 1872. 136,327LeslieFeb. 25, 1873. 10. Oiling Thread. 10,975SingerMay 30, 185gApr. 15, 1873. 138,153Henry et al.Apr. 22, 1873. 138,412LeslieApr. 29, 1873. 142,042Rayor et al.Aug. 19, 1873. 143,046WGunnermanOct. 5, 1869. 98,389KassonDec. 28, 1869. 100,161LeslieFeb. 22, 1870. 101,446EckApr. 5, 1870. 103,755LeslieMay 3LeslieMay 31, 1870. 106,481HallAug. 16, 1870. 108,492LeslieOct. 18, 1870. 108,787HowardNov. 1, 1870. 116,715JohnsonJuly 4, 1871. 1LeslieOct. 18, 1870. 108,787HowardNov. 1, 1870. 116,715JohnsonJuly 4, 1871. 123, 168GoodrichJan. 30, 1872. 124,853PetersonMar. 19, 1872. 125,032DaltonMar. 19, 1872. 125,608MooreApr. 9, 1872. 126,467Lawrence et al. May 7, 1872. 129,352LeslieJuly 16, 1872. 131,857DaltonOct. 1, 1872. (Reissue.)6,159ArnoldDec. 1, 187ScharffeMay 28, 1872. 129,087BishopJuly 16, 1872. 129,351LeslieJuly 16, 1872. 130,189ChamberlainAug. 6, 1872. 130,522Mootrument afterward constructed on the same principle by Sir John Leslie was by him termed a coniometer. Stere-o-mon′o-scope
nace. The expansion of the iron by heat is considerable, compared with that of the porcelain, and their difference measures the temperature. Pyrometer. In Leslie's differential thermometer (Fig. 6359), two globes containing air are connected by a bent tube partially filled with liquid. When both globes are at the same teut if their temperature be unequal, the greater expansion of the air in the more heated globe causes the liquid in the opposite leg to stand at a higher level. Leslie's differential thermometer. Rumford's thermoscope. Rumford's thermoscope (Fig. 6360) is analogous to the foregoing, the vertical branches of the tube being rences of temperature. The term was applied by Count Rumford to an instrument invented by him, and similar in principle to the differential thermometer of Professor Leslie. See differential thermometer. See also Fig. 6360. Any instrument which shows variations of temperature, whether or not it indicates the actual differenc
en used as wicks; asbestus was used by the ancients, and is yet used by the moderns. Gordon's English patent, many years since, described wicks composed of glass, metallic wire, or ashestus in fine filaments, formed into small bundles and bound spirally with wire or wrapped in wiregauze. The liquid is conveyed by capillary attraction in the fine interstices between the parallel filaments to the flame. Inventors have not entirely neglected the subject, as the following with indicate:— Leslie, October 26, 1858. A wick composed of a single yarn, double-looped. Wortendyke, April 26, 1859. A lamp-wick composed of strands that have received a preparatory twist in one direction are then spun in a contrary direction with and coiled upon a thread, and are then twisted together. Weeden, January 1, 1861. A wick composed of a single strand in a series of single loops. McKee, December 23, 1862. A lamp-wick made out of pulp, and felted or hardened together, instead of being wove