558 INDEX. 



Page. 



Tornado generally accompanied by gyratory motion 298 



Tornadoes investigated by numerous American meteorologists 292 



Totten, Gen. J. G., observations of, on sudden disappearance of ice. 198 



Trade-wind belts shifting with the sun's varying declination 282 



Trade-winds, cause of oblique motion of 53 



Trade-winds, effect of, on ocean currents .. 15 



Trade-winds, explanation of 276 



Trade-winds, northern, distributed in three belts 16, 17 



Trade-winds perturbed by the Eocky mountain range 84 



Transactions of Society for Encouragement of Arts, cited 429 



Transverse vibrations of the jcther assumed to explain polarization. 103 

 Tree-trunks, the annular growths of, indicating the character of 



seasons . 190, 191 



Tubular lightning-rods preferable, if sufficiently heavy 399 



Tyndall, Prof. John, experiments by, on plasticity of ice 202 



Undulations, interference of, illustrated 101 



Uniformity of weather indications by telegraph 441 



Vapor, atmospheric, non-diathemanous to heat of low intensity — 46 



Vapor, density of, proportional to its elasticity 224 



Vapor elasticity of, at diiFerent temperatures 217 



Vapor in the air, effect of, on atmospheric electricity 357, 358 



Vapor in the air, elastic force of, increasing with elevation 268 



Vapor less elastic from the ocean than from fresh water 221 



Vapor sometimes increasing, sometimes diminishing the weight of 



the air 270 



Vapor, the latent heat of, very great 225 



Vapor, the weight of, at different temperatures 225 



Vapor, the weight of, method of determining 222, 223 



Vapor, weight and elasticity of, not aff'ected by the presence of 



other gases 225, 231 



Vegetation, annual consumption by, of one-ninth of the carbon in 



the atmosphere 164 



Vegetation supposed to absorb miasma 171, 173 



Vegetation, the process of, not a probable cause of atmospheric 



electricity 347 



Vegetative processes, times of, in difl"erent plants 188, 189 



Vitality capable of indefinite extension, and therefore not a power. 459 



Vitality a directing principle, not a mechanical energy 116, 117, 457, 459 



Vitreous or positive electricity, how produced 317 



Volcanic ashes transported by the air to great distances 255 



Volcanic smoke carried over a great part of Europe 281 



Volta, demonstration by, that the earth is negatively electrified — 349 



Volta, observation by, of "hour-glass" form of thunder-cloud 361 



Von Guericke, water barometer devised by 421 



