| Description | Tables of magnetic declinations [pp.1-2] recorded at five minute intervals, twelve observations per hour, from 10.00pm on 27 November to 10.00am on 28 November 1840. With corresponding readings of magnetic intensities [pp.3-4].
The Royal Society's interest in magnetic observations at this period was in response to a letter by Alexander von Humboldt, 23 April 1836, to William Parsons, 3rd Earl of Rosse and President of the Royal Society, proposing an international network of observatories [AP/20/7]. |