Gompertz, Benjamin (DNB00)

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GOMPERTZ, BENJAMIN (1779–1865), mathematician and actuary, descended from the distinguished Jewish family of Gompertz of Emmerich, was born on 5 March 1779, in London, where his father and grandfather had been successful diamond merchants. Debarred, as a Jew, from a university education, he studied without guidance from an early age, and when a mere lad was familiar with the writings of Newton, Maclaurin, and Emerson. As early as 1798 he was a prominent contributor to the ‘Gentleman's Mathematical Companion,’ and for a long period carried off the annual prizes of that magazine for the best solutions of prize problems. In compliance with his father's wish, he entered the Stock Exchange, but continued his private studies. He became a member of the Old Mathematical Society of Spitalfields, and served as its president when it was merged in the Astronomical Society. From 1806 he was a frequent contributor to the ‘Transactions’ of the Royal Society; but his early tracts on imaginary quantities and porisms (1817–18), which first established his reputation as a mathematician, were declined by the society, and were printed and published at his own expense. In 1819 he was elected a F.R.S., and in 1832 became a member of the council. The foundation of the Astronomical Society in 1820 opened to Gompertz a fresh field of activity. He was elected a member of the council in 1821, and for ten years actively participated in its work, contributing valuable papers on the theory of astronomical instruments, the aberration of light, the differential sextant, the convertible pendulum, and other subjects. With Francis Baily [q. v.] he began in 1822 the construction of tables for the mean places of the fixed stars; the work was left uncompleted, because, in the midst of their calculations, Baily and Gompertz found themselves anticipated by the publication of the ‘Fundamenta Astronomiæ’ of Bessel. Their labours, however, resulted in the complete catalogue of stars of the Royal Astronomical Society. Gompertz may be regarded as the last of the old English school of mathematicians. So great was his reverence for Newton that he adhered to the almost obsolete language of fluxions throughout his life, and ably defended the fluxional against what he called ‘the furtive’ notation (Phil. Trans. 1862, pt. i. p. 513).

It was as an actuary that Gompertz's most lasting work was performed. On the death of an only son he retired from the Stock Exchange, and absorbed himself in mathematics. When the Guardian Insurance Office was established in 1821, he was a candidate for the actuaryship, but the directors objected to him on the score of his religion. His brother-in-law, Sir Moses Montefiore—he married Abigail Montefiore in 1810—in conjunction with his relative Nathan Rothschild, thereupon founded the Alliance Assurance Company (1824), and Gompertz was appointed actuary under the deed of settlement (Martin, Hist. of Lloyd's, p. 292). Some years previously he had worked out a new series of tables of mortality for the Royal Society, and these suggested to him in 1825 his well-known law of human mortality, which he first expounded in a letter to Francis Baily. The law rests on the à priori assumption that a person's resistance to death decreases as his years increase, in such a manner that at the end of equally infinitely small intervals of time he loses equally infinitely small proportions of his remaining power to oppose destruction. ‘Had this principle been propounded in the days of Newton,’ says Professor De Morgan, ‘vitality would have been made a thing of, like attraction.’ His management of the Alliance Company was very successful. He was frequently consulted by government, and made elaborate computations for the army medical board. In 1848 he retired from active work and returned to his scientific labours. He was a member of numerous learned societies besides those already mentioned, and was also one of the promoters of the Society for the Diffusion of Useful Knowledge. Of the leading Jewish charities he was a prominent member, and he worked out a plan of poor relief (Jewish Chronicle, 6 Oct. 1845), which was afterwards adopted by the Jewish board of guardians. Gompertz died from a paralytic seizure on 14 July 1865.

[Memoir in the Assurance Magazine, xiii. 1–20, by M. N. Adler; Monthly Notices of Astr. Soc. xxvi. 104–9; Athenæum, 22 July 1865, by Professor De Morgan; List of Works in Notes and Queries, 2nd ser. x. 163.]

L. W.