The meteorological observations contain at least 30 volumes spanning 1748-1822. Maintained by William Adair, Peter Legaux, James Madison, Phineas Pemberton, and other prominent figures from the early national period, these volumes capture meteorological data, thermometer readings, winds, and occasionally longitudes, latitudes, graphs, and miscellaneous notes. Phineas Pemberton recorded approximately half of the volumes, in or around Philadelphia during colonial and revolutionary period (August 1748-December 1776). Other volumes record meteorological data from New England (Samuel Williams), Natchez (William Dunbar), and Peru and northern Chile (Samuel Curson). Scholars researching late-eighteenth and early-nineteenth weather conditions will be well-served by this collection.