278. The Height of 10 Miles seems not too great to limit human Respiration, shoud any Attempt be made, to soar with a Balloon in a mild Atmosphere; and particularly between the Tropics.[85]
But an Objection woud be found in the Size of a Balloon sufficiently capacious to contain nearly 6 Times the Bulk to which the Gass woud necessarily expand itself, at the Height of 10 Miles.
First Cause of Limitation, in the Ascent of Balloons.
Second Cause of Limitation in the Ascent of Balloons.
279. It seems most likely that the primary Cause that will affect the Ascent of Balloons is the Difficulty of encreasing the Dimension of the Balloon: the Second, is from the excessive Cold; if the Wind blows from any Points of the North.
Supposing the Construction of the Atmosphere to be as represented by different Authors, (which, by the Way, is scarcely credible) ten Miles will perhaps be the utmost attainable Height.
280. There is a Circumstance relative to the Motion of the Air, which has not been sufficiently attended to: and bears some Analogy with that of a Thorough Air.
This Circumstance may not improperly be called the Reception and Dispersion of Air.
In cold Climates, it is an Object of Dread: in warm ones, a most desirable Piece of Luxury.
A gentle Undulation of the Air is perceived in Peru, and other hot Climates, by Persons sitting in Arbours sheltered from the Sun.