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# John Henry Pratt

John Henry Pratt (June 4, 1809 - December 28, 1871) was a British clergyman and mathematician who devised a theory of crustal balance which would become the basis for the isostasy principle.

Pratt was born in London and educated as a mathematician at Cambridge University. He wrote Pratt's Mechanical Philosophy, full title: The Mathematical Principles of Mechanical Philosophy and their application to Elementary Mechanics and Architecture, but chiefly to The Theory of Universal Gravitation, a textbook of some 600 pages. While serving as the Archdeacon of India, Pratt arrived at his theory of crustal balance based upon a survey of India. He died in Ghazipur, India.

External links

* O'Connor, John J.; Robertson, Edmund F., "John Henry Pratt", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Pratt.html .

* Extracts from the Royal Society of London

* The Mathematical Principles of Mechanical Philosophy by John Henry Pratt M.A. (Google Books)

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