On November 30,1784, American physician John Jeffries (1745-1819) and French inventor Jean Pierre Blanchard (1753-1809) flew in a balloon from London to Stone Marsh, Kent. Dr Jeffries was the first American to fly, as well as the first meteorologist; and this flight was the occasion for the first airborne scientific observations of the atmosphere. To amuse himself, Dr Jeffries wrote four notes to friends and dropped them over the side. Three of them were found and delivered to their addresses. The only one of these that still survives was addressed to Mr. Arodie Thayer. This note, considered the oldest piece of airmail in existence, was gifted to Amherst College by his nephew Thatcher Thayer (AC 1831).

The note is a badly stained, yellowed 3 x 5 card. The original is thought to have been written in a quick-fading ink made from pokeberries, and to have been traced over subsequently (and not always correctly) with pencil. Despite the tracer's efforts, a good portion of the note is too indistinct to be decipherable.

The collection consists of the original airmail letter written by Jeffries plus the following: several photographic reproductions, various clippings relating to the letter, correspondence about its preservation, and a scrapbook compiled by S.R. Williams, director of the Snell Museum of Physics at Amherst College, presented to the College in 1947.