Benjamin Franklin and the First Balloons

Benjamin Franklin and the First Balloons
ABBOTT LAWRENCE ROTCH
Reprinted from the Proceedings of the American Antiquarian Society Volume XVIII
WORCESTER, MASSACHUSETTS THE DAVIS PRESS 1907
BY ABBOTT LAWRENCE ROTCH.
The recent bi-centenary of Franklin’s birth, which coincided with the revival of interest in balloons, makes this a timely topic, especially since Franklin’s descriptions of the first balloon ascensions are almost unknown and do not appear among his philosophical papers. The five letters which I have the honor to present were written to Sir Joseph Banks, President of the Royal Society of London, in 1783, when Franklin was Minister to the Court of France and, with the collateral documents, they give perhaps the most complete and accurate account of the beginning of aerial navigation, enlivened with the humor and speculation characteristic of the writer. It is certainly remarkable that Franklin, in the midst of diplomatic and social duties, could have found time to investigate personally this new invention of which he at once appreciated the possibilities.
Passy, Aug. 30, 1783.
Sir,
On Wednesday, the 27 th Instant the new aerostatic Experiment, invented by Mess rs . Montgolfier, of Annonay, was repeated by M. Charles, Professor of experimental Philosophy at Paris.
A hollow Globe 12 feet Diameter was formed of what is called in England Oiled Silk, here Taffetas gommé , the Silk being impregnated with a Solution of Gum elastic in Lintseed Oil, as is said. The Parts were sewed together while wet with the Gum, and some of it was afterwards passed over the Seams, to render it as tight as possible.
It was afterwards filled with the inflammable Air that is produced by pouring Oil of Vitriol upon Filings of Iron, when it was found to have a tendency upwards so strong as to be capable of lifting a Weight of 39 Pounds, exclusive of its own Weight which was 25 lbs. and the Weight of the Air contain’d.
It was brought early in the morning to the Champ de Mars , a Field in which Reviews are sometimes made, lying between the Military School and the River. There it was held down by a Cord till 5 in the afternoon, when it was to be let loose. Care was taken before the Hour to replace what Portion had been lost, of the inflammable Air, or of its Force, by injecting more.