**Logistic** or Proportional Logarithms. - The old name for what are now called ratios or fractions are **logistic** numbers, so that a table of log (a/x) where x is the argument and a a constant is called a table of **logistic** or proportional logarithms; and since log (a/x) =log a-log x it is clear that the tabular results differ from those given in an ordinary table of logarithms only by the subtraction of a constant and a change of sign.

The usual practice in books seems to be to call logarithms **logistic** when a is 3600", and proportional when a has any other value.

**Logistic** or Proportional Logarithms. - The old name for what are now called ratios or fractions are **logistic** numbers, so that a table of log (a/x) where x is the argument and a a constant is called a table of **logistic** or proportional logarithms; and since log (a/x) =log a-log x it is clear that the tabular results differ from those given in an ordinary table of logarithms only by the subtraction of a constant and a change of sign.

In most collections of tables of logarithms, and especially those intended for use in connexion with navigation, there occurs a small table of **logistic** logarithms in which a = 3600"(= I° or I h), the table giving log 3600 log x, and x being expressed in minutes and seconds.

Among these subjects were the transit of Mercury, the Aurora Borealis, the figure of the earth, the observation of the fixed stars, the inequalities in terrestrial gravitation, the application of mathematics to the theory of the telescope, the limits of certainty in astronomical observations, the solid of greatest attraction, the cycloid, the **logistic** curve, the theory of comets, the tides, the law of continuity, the double refraction micrometer, various problems of spherical trigonometry, &c. In 1742 he was consulted, with other men of science, by the pope, Benedict XIV., as to the best means of securing the stability of the dome of St Peter's, Rome, in which a crack had been discovered.