To Thomas Jefferson from Caspar Wistar, Jr., [9 January 1793]
From Caspar Wistar, Jr.
Wednesday Morning [9 Jan. 1793]
Dr. Wistars respectful Compliments to Mr. Jefferson and sends the Vials for which he requests Mr. J. to procure a passage in the Balloon. Three facts may be ascertained by bringing down some of the upper Atmosphere—viz The proportion of pure air; The proportion of fixed air, or the absence of it; and the Comparative state of Expansion of the Atmosphere. To ascertain this last Circumstance the temperature of the air at the time of inclosing it should be noted. The State of the Barometer must of course be marked.
P.S. Mr. Blanchard must be requested to empty the Bottles and Cork them well at the greatest height.
RC (MHi); partially dated; dateline between body of letter and postscript; endorsed by TJ as received 9 Jan. 1793 and so recorded in SJL.
TJ’s purchase of a $5 admission ticket for the event indicates that he, along with President Washington, French minister Jean Baptiste Ternant, and an “immense number of people,” was present this morning in the courtyard of the Walnut Street Prison in Philadelphia to witness the balloon ascent of Jean Pierre Blanchard (1750–1809), the veteran French aeronaut who had come to the United States exactly a month before to “convince the New World that man’s ingenuity is not confined to earth alone, but opens to him new and certain roads in the vast expanse of heaven.” During this flight, the first successful manned ascent in America, Blanchard traveled some fifteen miles from Philadelphia to Deptford in Gloucester County, New Jersey, in forty-six minutes and performed scientific experiments for a number of Philadelphia physicians and natural scientists, including Wistar, who actually placed the six vials in question in Blanchard’s balloon car (Blanchard, Journal of my Forty-Fifth Ascension, being the First Performed in America, On the Ninth of January, 1793 [Philadelphia, 1793], 7–27; , 9 Jan. 1793). The ever-curious TJ closely questioned Blanchard shortly afterward about methods of producing hydrogen and subsequently contributed $20 to help cover the cost of his flight and $1 to watch the aeronaut’s parachute experiments with animals (Note on Balloons, [ca. 9 Jan. 1793]; TJ to Martha Jefferson Randolph, 14 Jan. 1793, and note; , 9 Apr., 17 June 1793). However, TJ subsequently rejected Blanchard’s request that he ask the President for a loan of $400 and regretted his own inability to assist the balloonist privately (Blanchard to TJ, 16 Oct. 1793; TJ to Blanchard, 15 Dec. 1793). For Blanchard’s prior aeronautical career in France, which began in 1784 and included a successful flight across the English Channel the following year, see Dictionnaire de biographie française, 15 vols. [Paris, 1933– ], vi, 604–5; and Charles C. Gillispie, The Montgolfier Brothers and the Invention of Aviation, 1783–1784 (Princeton, 1983), 87, 95, 97, 119–20.