History of Logarithms

HISTORY OF LOGARITHMS 1ST SOURCE: (sosmath. com) Logarithms were invented independently by John Napier, a Scotsman, and by Joost Burgi, a Swiss. The logarithms which they invented differed from each other and from the common and natural logarithms now in use. Napier’s logarithms were published in 1614; Burgi’s logarithms were published in 1620. The objective of both men was to simplify mathematical calculations. Napier’s approach was algebraic and Burgi’s approach was geometric. Neither man had a concept of a logarithmic base.

Napier defined logarithms as a ratio of two distances in a geometric form, as opposed to the current definition of logarithms as exponents. The possibility of defining logarithms as exponents was recognized by John Wallis in 1685 and by Johann Bernoulli in 1694. The invention of the common system of logarithms is due to the combined effort of Napier and Henry Biggs in 1624. Natural logarithms first arose as more or less accidental variations of Napier’s original logarithms. Their real significance was not recognized until later. The earliest natural logarithms occur in 1618.

Logarithms are useful in many fields from finance to astronomy. 2nd SOURCE: (en. wikipedia. com) The method of logarithms was first publicly propounded in 1614, in a book entitled Mirifici Logarithmorum Canonis Descriptio, by John Napier, Baron of Merchiston, in Scotland. (Joost Burgi independently discovered logarithms; however, he did not publish his discovery until four years after Napier. ) Early resistance to the use of logarithms was muted by Kepler’s enthusiastic support and his publication of a clear and impeccable explanation of how they worked.

Their use contributed to the advance of science, and especially of astronomy, by making some difficult calculations possible. Prior to the advent of calculators and computers, they were used constantly in surveying, navigation, and other branches of practical mathematics. It supplanted the more involved method of prosthaphaeresis, which relied on trigonometric identities as a quick method of computing products. Besides the utility of the logarithm concept in computation, the natural logarithm presented a solution to the problem of quadrature of a hyperbolic sector at the hand of Gregoire de Saint-Vincent in 1647.

At first, Napier called logarithms “artificial numbers” and antilogarithms “natural numbers”. Later, Napier formed the word logarithm to mean a number that indicates a ratio: (logos) meaning proportion, and (arithmos) meaning number. Napier chose that because the difference of two logarithms determines the ratio of the numbers they represent, so that an arithmetic series of logarithms corresponds to a geometric series of numbers. The term antilogarithm was introduced in the late 17th century and, while never used extensively in mathematics, persisted in collections of tables until they fell into disuse.

Napier did not use a base as we now understand it, but his logarithms were, up to a scaling factor, effectively to base 1/e. For interpolation purposes and ease of calculation, it is useful to make the ratio r in the geometric series close to 1. Napier chose r = 1 – 10? 7 = 0. 999999 (Burgi chose r = 1 + 10? 4 = 1. 0001). Napier’s original logarithms did not have log 1 = 0 but rather log 107 = 0. Thus if N is a number and L is its logarithm as calculated by Napier, N = 107(1 ? 10? 7)L. Since (1 ? 10? 7)107 is approximately 1/e, this makes L/107 approximately equal to log1/e N/107.

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