February 5 is Meteorologists Day in honor of John Jeffries (5 February 1745 – 16 September 1819) who as early at 1774 took daily weather measurements in Boston. Jeffries also made the first balloon flight over London in 1784 with the purpose of gathering data for a scientific study of the air at high altitudes. The Archives and Special Collections at Amherst College holds a collection of his papers, including a letter he dropped from the balloon during his historic flight, considered the oldest piece of airmail in existence.
Summarized from Wikipedia.
This engraving of Jeffries is from the book Wonderful Balloon Ascents, or the Conquest of the Skies, a History of Balloons and Balloon Voyages by Fulgence Marion (pseudonym of Camille Flamarrion.) I accessed it through the wonderful and free Internet Archives. It is in the public domain.