On a wooden base, provided with levelling screws, a graduated copper rule, about a yard long, is fixed edgeways. On this rule the various parts composing the apparatus are placed, and their distances can be fixed by means of binding screws. a is a support for a Locatelli's lamp, or other source of heat; F and E are screens; C is a support for the bodies experimented on, and m is a thermo electrical battery. Near the apparatus is a galvanometer, D, which has only a comparatively few turns of a tolerably thick (1 mm.) copper wire. Such galvanometers are called thermomultipliers. The delicacy of this apparatus is so great that the heat of the hand is enough, at a distance of a yard from the pile, to deflect the needle of the galvanometer, Blood globules, 8 Binocular vision, 372 Bodies, equilibrium of, 44; general Boiling, 232; laws of, 233 Bologna, Tower of, 46 Boyle's law, 132 Brahma's press, 82 British units, 103 Buffon's burning mirrors, 201 Bulging of earth at the equator, 30 Bunsen's battery, 447; burner, 338 Bunten's barometer, 122 Burning glasses, 331; mirrors, 201 Condensers, limit of charge of, 414 DAGUERREOTYPE, 366 Damper of piano, 177 Dancing puppets, 406 262 Dark lines of the spectrum, 336 Degrees, Fahrenheit, 190; Réaumur, 190 Density 2, of gases, 218 Dew, 273; point, 262 ELE Dial telegraph, 468 Differential thermometer, 193 Digester, 235 Dip, magnetic, 383 Discharge, slow and instantaneous, 413 Discharger, universal, 421 Discharging rod, 413 Dispersion of light, 333 Dissolving views, 360 Dissonance, 169 Distance of distinct vision, 371 Distillation, 242 Divisibility, 8 Dynamometer, 22 Dominant chords, 169 Dove's law of rotation of winds, 279 Double action machine, 249; descrip- tion of, 250 FAR trumpet, 165 Earth currents, 434 Earth, flattening of at the poles, 30; Egg, electric, 408 Elastic force of aqueous vapour, 236; Elasticity, 12, 13 Electric batteries, 416; egg, 408; spark, 405, 421; telegraphs, 468 Electric light, 450; stratification of, Electrical fluids, hypothesis of two, Galvanic shock, 448 Gases and liquids, mixture of, 136 Glaisher's factors, 262 |