father exacted the weekly payment of 2s. 6d. till the boy was seven.
He was educated first at the school of his native village; secondly, at that of Byfield; and thirdly, at that of Medford. It is said (G. E. Ellis, Memoir, p. 15) ‘that he showed a particular ardour for arithmetic and mathematics, and it was remembered of him, afterwards, that his playtime, and some of his proper worktime, had been given to ingenious mechanical contrivances, soon leading to a curious interest in the principles of mechanics and natural philosophy.’
When fourteen he was apprenticed to John Appleton of Salem, who kept a large ‘store,’ remaining there ‘till about October 1769.’ He busied himself with experiments for the discovery of perpetual motion and the preparation of fireworks. An unforeseen explosion jeopardised his life. In 1769 he entered the employment of Hopestill Capen of Boston. His spare time was devoted to learning French and to fencing. He attended lectures at Harvard University, and acquired some knowledge of surgery and medicine. The disputes between the colonies and the motherland having brought commerce to a standstill, he became a schoolmaster, first at Wilmington in Massachusetts, and afterwards at Rumford (subsequently renamed Concord) in New Hampshire. Being handsome in feature and figure, and about six feet in height, he found favour in the eyes of Sarah (1739–1792), daughter of the Rev. Timothy Walker of Rumford, and widow of Colonel Benjamin Rolfe (d. 1771), the squire of Rumford. The lady had one child (afterwards Colonel Paul Rolfe) and a competence. Rumford married her in January 1773; he was under twenty and she was thirty-three. Their only child, Sarah, was born on 18 Oct. 1774. Wentworth, the governor of New Hampshire, gave him a commission as major in the second provincial regiment, greatly to the dissatisfaction of the junior officers. He now devoted his leisure hours to experiments in gunpowder and to farming the land acquired by marriage.
In 1775 he was cast into prison for lukewarmness in the cause of liberty, and was released, without being acquitted, after the committee of safety had failed to prove his guilt. He then converted his property into cash, embarked on the frigate Scarborough at Newport, and was landed at Boston, where he remained till the capitulation, sailing for England in the frigate bearing despatches from General Gage to Lord George Germain [q. v.], secretary of state. Lord George appointed Thompson secretary for Georgia, a barren honour, and to a place of profit in the colonial office. He again occupied himself with experiments in gunpowder; he determined the velocity of projectiles while advantageously altering their form, and he succeeded in getting bayonets added to the fusees or carabines of the horse-guards for use when fighting on foot. A paper on the cohesion of bodies which he sent to the Royal Society led to the formation of an acquaintance with Sir Joseph Banks, and to his election as a fellow on 22 April 1779. In the same year he made a cruise as a volunteer in the Victory belonging to the squadron under Sir Charles Hardy, when he studied the firing of guns, and obtained ‘much new light relative to the action of fired gunpowder.’
In September 1780 he was appointed under-secretary for the colonies, an office which he held for thirteen months, during which, as Cuvier stated on Thompson's authority (Memoir, p. 121), ‘he had been disgusted with the want of talent displayed by his principal [Lord George Germain], for which he had himself not unfrequently been made responsible.’ Lord George appointed Thompson lieutenant-colonel of the king's American dragoons after Cornwallis had surrendered to Washington and Rochambeau at Yorktown; and, though he did some skirmishing at Charleston before its evacuation, his career in America as a soldier was uneventful. He went with his regiment from Charleston to Long Island, where he remained at Huntingdon till peace was concluded. The historians of Long Island denounce him for having acted as a barbarian in pulling down a presbyterian church and using the materials for building a fort in the public burying-ground (Thompson, Hist. of Long Island, i. 211, 478; Prime, Hist. of Long Island, pp. 65–6, 251).
Returning to England, he retired from the army on half-pay, and went abroad on 17 Sept. 1783, one of his fellow-passengers between Dover and Boulogne being Gibbon (Gibbon, Letters, ii. 72). Thompson journeyed to Strassburg, was present in uniform at a review, and formed the acquaintance of Duke Maximilian, the general in command, and was introduced by him to his uncle, the elector of Bavaria, into whose service he afterwards entered. George III not only gave Thompson the requisite permission, but knighted him on 23 Feb. 1784, shortly before his departure for Bavaria. He returned to England in October 1795 with the title of Count von Rumford. During the eleven years he passed in Munich he had made important reforms in the public service and in social economy. As minister of war he increased the pay and comfort of
