Page:Lectures on Ten British Physicists of the Nineteenth Century.djvu/91

 private pupils, and began to read extensively with a view of following in the footsteps of Francis Bacon. He was soon appointed one of the mathematical tutors of his college. His connection with the Analytical Society suggested his first work An Elementary Treatise on Mechanics, in which the continental notations for the calculus is used. It was a great advance on any existing text-book on the subject used at Cambridge; subsequently it passed through several editions and became much altered. In 1820 Whewell was one of the moderators at the tripos examinations, and, following the example of Peacock the year before, he made use of the d notation. He was not an ardent reformer like Peacock; he appeared to have waited until the success of the movement was apparent. Although his first book was on Mechanics, his main design, even then, was a work on the inductive philosophy in which he should take full advantage of what had been accomplished in the physical sciences since the time of Bacon. For this reason we find him at an early age studying Locke's Essay on Human Understanding and Kant's Critique of Pure Reason.

In those days a fellowship expired at the end of seven years unless the holder took holy orders. Whewell took orders in 1826; in the same year he and Airy, the Lucasian professor of mathematics, made observations in a mine in Cornwall to determine the mean density of the earth. Bacon, more than two centuries earlier, had suggested swinging a pendulum in a deep mine for this purpose. Airy and Whewell attempted to determine the time of oscillation of a pendulum at the bottom of the mine—about 1200 feet deep—and to compare it with that of another pendulum on the surface. An accident to the pendulum vitiated the first series of observations. Two years later they made a second series, which was also unsuccessful on account of an accident in the mine. Nearly thirty years later Airy, however, made successful observations at another mine from which he deduced 6.565 as the mean density of the earth as compared with water. At the time when Whewell took orders the professorship of mineralogy at Cambridge fell vacant; it appears to have been occupied as asinecure. Whewell