Kelly, Patrick

(1755/6-1842), mathematician and astronomer

by R. E. Anderson, rev. Anita McConnell

© Oxford University Press 2004 All rights reserved

Kelly, Patrick (1755/6-1842), mathematician and astronomer, was for many years master of the Finsbury Square Academy, London. Nothing is known of his parentage or early life; on 1 August 1789 he married Ann Plomley, who predeceased him. Their son, later the Revd Anthony Plomley Kelly (b. 1797), survived him. The Finsbury Square Academy, a finishing school teaching commercial and mathematical subjects, comprised a boarding-house, schools, and an observatory. Kelly published for the use of his students Practical Introduction to Spherics and Nautical Astronomy (1796), which reached a fifth edition; Elements of Book-Keeping (1802), which reached a seventh edition; and The Ship-Master's Assistant and Owner's Manual (1803), which continued to a twentieth edition, latterly in other hands. He was appointed mathematical examiner at Trinity House, and in 1809 the degree of LLD was conferred on him by the University of Glasgow.

The series of works for which Kelly was best known dealt with the rates of exchange of currencies, and the equivalence of weights and measures employed in different countries. At the end of the eighteenth century English merchants lacked any reliable guide to rates of exchange comparable with J. E. Kruse's Allgemeiner und besonders Hamburgischer Contorist (1753) prepared for the Hamburg merchants. The Bank of England in 1796 declined to undertake a similar task, and in 1804 Kelly submitted a prospectus for an expanded and updated version of Kruse's work. The bank then agreed to support Kelly, as did the Board of Trade, East India Company, and leading mercantile houses. His Universal Cambist (1811) dealt with the moneys, coins, weights, and measures 'of all trading nations', and surpassed Kruse by including the East and West Indies and America. The Bank of England had assayed the gold and silver content of the coins, but Kelly could not procure foreign standards of weight and measure during the war years, and had perforce to rely on the equivalents provided by merchants. When peace came, the government issued a circular to all British consuls to obtain standards; these were compared at the Royal Mint. The first edition of the Cambist showed up the earlier defective exchange rates, especially in Spanish and French currencies, which had cost England dear, and these new and corrected values were published in the second edition in 1821.

The East India Company then agreed to provide Kelly with examples of the weights and measures in regions under its control; his work was completed in 1823; his comparisons were then verified, the weights at the mint, the measures by the instrument maker Edward Troughton. Kelly submitted several requests for payment for this exercise, but this was at first refused, the company declaring that it would subscribe to forty copies but that Kelly should expect nothing more. In the end a small payment was made, rather less than Kelly had received for his calculations made for a House of Commons committee. The material was appended to the chapter on the East Indies in the Cambist, and a separate Oriental Metrology was published in 1832.

Kelly enjoyed the friendship of astronomers and mathematicians, schoolmasters, and men of science of the day, among them Nevil Maskelyne, William Herschel, Samuel Vince, Charles Hutton, and Matthew Raine. His opinions were sought by committees of both houses of parliament on matters of currency and exchange. In retirement Kelly lived at Western Cottages, Brighton, Sussex, where he died on 5 April 1842.


GM, 2nd ser., 18 (1842), 434-5
Annual Register (1842)
D. Vaughan, 'Patrick Kelly and the Castlereagh Collection', Science Museum Review 1989 (1989), 40-42
W. I. Addison, A roll of graduates of the University of Glasgow from 31st December 1727 to 31st December 1897 (1898), 303
East India Company court minutes, BL OIOC, B/176-7, 179-80
parish register (marriage), London, Lothbury, St Margaret, 1 Aug 1789

T. Woolnoth, stipple (after H. Ashby), BM, NPG

Oxford University Press 2004 All rights reserved


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