Description | Drawings, calculations and correspondence relating to the design of a magnetometer to measure the magnetic fields of a rotating sphere (see Bernard Lovell, 'P.M.S. Blackett: A Biographical Memoir', Royal Society: 1976, pp41-43).
This magnetometer was designed to test the hypothesis advanced in Blackett's 1947 paper ('The magnetic field of massively rotating bodies') of a relation between the magnetic moment and the angular momentum of massive rotating bodies. He began to plan its design immediately after the publication of his paper, and observations are recorded from 9 August 1947 (see C.30-C.32 for laboratory notebooks of observations on the apparatus). The sensitivity of the instrument enabled earlier experiments, by Swann and Longacre, Schuster and Wilson, and others, to be further tested, a negative result being obtained and presented in Blackett's 1952 paper ('A negative experiment relating to magnetism and the Earth's rotation').
This magnetometer thus disproved Blackett's own 1947 hypothesis, which had attracted great attention at the time, but its superior sensitivity made possible further advances in paleomagnetism. |