Sir John Henry Lefroy

(1817—1890) army officer and meteorologist

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(1817–90), soldier and scientist, born and died in England. Graduating from the Royal Military Academy in 1834, Lefroy joined the Royal Artillery. In 1839 he helped staff a worldwide network of British observatories organized by Edward Sabine, RA, and the Royal Society of London to study the earth's magnetism. After a stint at St Helena, Lefroy directed the Toronto observatory from 1842. With one assistant he surveyed geomagnetic variations northwest to the Arctic Circle in 1843–4, publishing important scientific results in 1855. Lefroy also undertook detailed magnetic and meteorological observations at Toronto, introducing photographic and self-registering instruments to ensure a continuous record of change as settlement progressed. Active in Toronto society (he married John Beverley Robinson's daughter in 1846) and its institutions, he evinced an evangelical zeal for education. Returning to England in 1853, he persuaded the provincial government to continue the Toronto observatory—and Egerton Ryerson to require daily weather observations of grammar school headmasters. Internationally respected as a specialist on the aurora borealis who also pioneered a continental weather-warning system, Lefroy never elaborated the general geomagnetic theory that he sought. He capped his distinguished scientific career as a military adviser and colonial administrator.

From The Oxford Companion to Canadian History in Oxford Reference.

Subjects: History of the Americas.

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