- - for Expansion with Heat, from 1 to 40 Degrees, on Inches of the Barometer, from 9 to 32 Inches, 363 - the 2nd, shewing the Variations of the Barometer, at each Inch and Tenth of the Quicksilver, from 1 to 32 Inches, the Air being at the freezing Point, 371 - the 3d, for easy Calculations, from the 2d Table, 373 - the 4th, shewing the Expansion with Heat, from 1 to 100 Degrees, on any Number of Feet in the Air, 381 Tastes not altered, on Account of the Height, 65 Thermometer warmer _above_ than _below_, 126 Thermometers compared, 12, _c._ Thunder-Clouds described, 52 - - under the Balloon, 172 Tide of Air in the Atmosphere, 291 Tides highest, 288, 289 Time, noted, 7, 8, 11, 22, 28, 36, 62, 63, 68, 73, 77, 85, 100, 101, 124, 162, 174, 186, 203, 206 - of Ascent, 28 Time, in which the Excursion was performed, viz. two Hours and a Quarter, 191 - Noon, a dangerous one, for Balloons to pass an Arm of the Sea, 256 - the best, pointed out, 256 - Noon and full Tide, improper: Midnight and low Water, proper Hours for Ascent, over Water, 287 Torrents of Air mediocèanal, depressing, 257, 258, 259 - - - - - accumulating, 260 Transparency circular, of Vapour, 222 Twine cut, lest it should prove a Conductor of Electricity between the Balloon and Earth, 103 U. Useful Conclusions, 159 Utility of Balloons, 332, 333 Utility _general_, of Balloons, 338 V. Valve upper, emits the _lightest_ Gass, 124 - _first_ tried, 133 - -Swing, or Umbrella-Pendulum, as _propulsive_ Machinery, communicates a _progressive_ Motion to the Balloon, 319 Vane-Sail, 318 Vapour, Observation of the _reddish_, 33 - _white_, _beautiful_ Effects of, 71 - - began to be accumulated at a _certain_ Height, 80 Vapours, their _Transparency_, 222 Varnishes, 320, 325 Velocity of the Balloon, 192 Vessels, the _four_ and the River Wever _disappeared_, 110 View _circular_, from the Balloon at its _greatest_ Elevation, 55 - of the Balloon over _Helsbye-Crag_,77 - of the Clouds, _from_ above _them_, 171 - _from_ the Balloon of the Country between Chester and Rixton-Moss, 192 Vis Inertiæ, 70, 316 W. Warmth of the superior Atmosphere, 275 - of the Air above Plains and cultivated Countries, 276 - of the Air over the _Sea_, at certain Times and Seasons, 276 - descending from _above_, 284 Water poured down, to observe the Effects of Air upon it, 74 - Balloon influenced on its Approach to, 76, 78 - Balloon above the Influence of, 131 - the Descent of Balloons over, 229 - the Causes of their Descent over, 230 - Absorption of, by Air, 247 - a curious Phenomenon seen on its Surface, 249, 250, _b._ - Means to prevent the Descent of Balloons over, and within its Influence, 294, 295 Waves of Air, 21 - of the Sea, the Dashing of, heard; the Sea being invisible, 80