July 10. 1784 Saturday.
May not the Ascent of Vapours be explained, or rather accounted for upon the Principle of the Air Balloon? Is not every Bubble of Vapour, that rises, an Air Balloon? Bubbles are formed at the Bottoms of Canals, Rivers, Ponds, rise to the Top, and mount up. These Bubbles are particles, or small quantities of inflammable Air, surrounded with a thin film of Water.
Champaign Wine, Bottled Porter &c. are full of Air Bubbles or Balloons. Set a Decanter or Tumbler of Water in the Sun, and thousands of Air Balloons are formed in the Water at the Bottom and on the Sides of the Glass. Turn the Glass aside so as to expose these Bubbles to the Air, many of them burst in an Instant, others do not, but continue sometime covered with a thin film of Water. Inflammable Air being lighter, than common Air, rises in it.
In the common Experiment with which Boys amuse them selves, the Air which is blown through the Tobacco Pipe, into the Soap Suds, is common Air, of equal Weight with that which surrounds the Bub ble and therefore will not ascend very high. But if inflammable Air were blown thro the Pipe instead of common Air, we should have a Series of Ballons aerostatiques, which would ascend like those of Montgolphier.1
1. The earliest “aerostatic experiments” (balloon flights), by the Montgolfier brothers and others in France, 1783–1784, attracted world-wide attention and are frequently alluded to in the correspondence of JA, Franklin, and Jefferson at this period. Among the Adams Papers is a colored drawing entitled “Bon Voyage, ” reproduced in this volume, showing the “Nouveau Globe Aérostatique inventée par M[essieu]rs. Charles et Robert; enlevé devant la Famille Royale le lundi 1er. Décembre 1783, à 1. heure 40. minutes.” On 19 Sept. 1784 the Adams family watched a balloon ascension from the Tuileries Gardens (AA2, Jour. and Corr. description begins Journal and Correspondence of Miss Adams, Daughter of John Adams, ... edited by Her Daughter [Caroline Amelia (Smith) de Windt], New York and London, 1841–1842; 2 vols. description ends , 1:18–19).