Early science in Cambridge / by R.T. Gunther.

  • Gunther, R. T. (Robert Theodore), 1869-1940.
Date:
1937
Catalogue details

Licence: In copyright

Credit: Early science in Cambridge / by R.T. Gunther. Source: Wellcome Collection.

    128/650 (page 84)
    And on the other side, Wordsworth has printed the private diary of a Trinity Undergraduate for the same period stating that in November 1793 he was reading ‘Ratios and Variable Quantities’, transcribing a Syllabus of Mechanics, and being taught Astronomy and Spherical Trigonometry by Mr. Tavel in Trinity, and attending Prof. Wollaston’s lectures in addition to his Classical classes. Wordsworth, Untv. Life, 589-91. The huge subject of Natural Philosophy was beginning to grow beyond the powers of one man, and specialization began even before the beginning of the 19th century. Notes on the separate branches of Physics may therefore be conveniently grouped under the heads to which they refer. Weighing the Earth The Rev. John Michell (1724-93) of Queens’ College had constructed an apparatus for determining the average density of the earth by measuring the attraction between two spheres of lead. At his death the apparatus passed to Francis J. Hyde Wollaston, the Jacksonian Professor, who wisely handed it over to Henry Cavendish, who carried out the experiment in 1798. A torsion balance was constructed with a metal rod about 2 yards long, suspended by a torsion wire, and carry¬ ing at each of its ends a leaden sphere 2 inches in diameter. This was started oscillating slightly, while two larger 8 in. spheres could be brought near the smaller spheres, and by exercising a gravitational pull upon them, would effect a change in the centre of oscillation. By reversing positions the centre of oscillation could be displaced in the opposite direction. After elimination of all suspected errors, Caven¬ dish arrived at the wonderful result of 5-48 for the mean density of the Earth. By his kinsman he was described as ‘the man who weighed the world, and buried his science and wealth in solitude and insignificance at Clapham ’. Nevile Maskelyne (1732-1811) of Trinity, Astronomer Royal for forty-six years, designed and carried out his well- known experiment to ascertain the density of the earth. For this it was necessary to measure the force with which two known masses attract one another. From such a