Jonathan Williams was born May 26, 1750 in Boston to Jonathan Williams, a patriot of the revolution and a prosperous merchant, and Grace (Harris) Williams, daughter of Benjamin Franklin's sister Anne. Williams traveled to England in 1770 and 1773 to continue his education and to make contacts through his granduncle. By the time he left England in 1776, he had established prosperous business connections in London, but left them to travel to France with Franklin. While in France, Williams worked as a US commercial agent and also studied military science, particularly fortifications. Williams remained in Europe pursuing various business interests until he returned with Franklin to America in 1785. He had married Marianne Alexander, daughter of William Alexander of Edinburgh, Scotland, on October 12, 1779. They eventually moved to Philadelphia, where Williams became an associate judge in the court of common pleas in 1796.
While in Philadelphia, Williams worked with Franklin on his later experiments and gained a reputation as a scientist in his own right. Williams was elected to the APS in 1787 and published results of his observations on temperature and barometrical readings, as well as a paper on sugar production, in the APS Transactions . In 1799 he published a treatise entitled Thermometrical Navigation . His scientific interests brought him to the attention of Thomas Jefferson, who became impressed with Williams' knowledge of fortifications. He was appointed major of the 2nd regiment of artillerists and engineers in the regular army in 1801; later that year he was made inspector of fortifications and commander of the post at West Point.
When the U.S. Military Academy was established in 1802, Williams became its first superintendent, but he resigned in 1803 following a dispute over rank and authority. Jefferson arranged for Williams to return to this post in 1805, with the rank of lieutenant-colonel and chief of engineers and with complete authority over the cadets. He planned and built most of the inner forts in New York harbor, including Fort Columbus, Fort Clinton, and Castle Williams. At the outbreak of the War of 1812, he asked for but was denied the command of Castle Williams, probably due to political differences with the secretary of war, William Eustis. He resigned his post and became brevet brigadier-general of the New York militia. Returning to Philadelphia, he served on a committee to ensure the defense of the Delaware. In his later years, he served as vice-president and corresponding secretary of the APS. He was elected to Congress in 1814, but died before he could take his seat.
From the guide to the Jonathan Williams Papers, 1763-1802, (American Philosophical Society)