The Improbability, therefore, (on Account of the Warmth of the Air at that Height, viz. 60°;) of having soared to so great an Altitude, seems to point out, that the shadows must have contributed a principal Share, in preventing a Sight of the public and Turnpike Roads.
[49] The magnitude of an Object decreases, as the squares of its Distance from the Eye increase.
At whatever Distance, for Example, the Eye can see any Object clearly; as at the Distance of a Foot, or a Yard, if the Object be removed to twice that Distance; it will appear 4 Times smaller than it did before: 2 multiplied into 2, equals 4, which is the Square of 2: in the same Manner, if the Object be removed to thrice the Distance from the Eye, it will appear 9 Times as small, as at the first Distance: for 3 into 3 gives 9, the Square of 3: and so of any farther Distance.
[50] See “Berkeley’s New Theory of Vision, Section 67.”
[51] Dr. Smith having Recourse to intervening Objects; the Writer cannot assent to the Validity of his Argument, illustrated by a well-known Figure, to solve the Appearance of the horizontal Moon. See “Priestley’s History of Light and Colours, Page 712.”
[52]Phil. Trans. for 1785, Part 1, Page 287.
[53]Cavallo’s Treatise on Air, Page 576. Vitriolic Acid Air, Alkaline Air, and other elastic Fluids, are instantly absorbed by Water; (Page 673.) Inflammable Air, and fixed Air, are likewise absorbed by water. (Page 434).
[54] Nam fit, ut interdum tanquam demissâ Columnâ In Mare de Cœlo descendat.—Lucr. L. 6. V. 425.
Una Eurus Notusque ruunt, creberque Procellis Africus. Also
Omnia Ventorum concurrere Prælia vidi. Virgil.
[55]Franklin’s Account of Whirlwinds and Waterspouts, in his Miscellaneous Tracts. Lowthorp’s Abridgement of Phil. Trans. Vol. 2. Page 103. Varenius Geogr. Gen. C. 21, Pag. 265. A clear Account of the Effects of a depression is to be met with in “the History of Jamaica, in 3 vols. vol. 3. Page 800, on Trade and Land Winds.”
[56] Mons. Maupertius has found, that the extreme Cold at Tornea, in the northern Regions beyond the Artic Circle, came directly from above: see “La Figure de la Terre,” Page 59. Il semble que le vent souffle—de tous Côtés à la Fois; et il lance la Neige avec une telle Impetuosité, qu’en un Moment tous les Chemins font perdus. “It seems that the Wind blows from all Points of the Compass at once,” &c.