V. On an electromagnetic method for the measurement of the horizontal intensity of the earth's magnetic field

Abstract

The instrument described in this communication is the outcome of a suggestion made by Sir Arthur Schuster in 1913. The writer was asked to express his opinion on the practicability of the suggestion and the conditions necessary to secure great accuracy in any measurements which might be made. It appeared that the method proposed would allow a determination of H, the horizontal magnetic intensity, to be made in a few minutes and with a probable error of only a few parts in one hundred thousand. The design of a standard instrument was therefore prepared and submitted to Sir Arthur Schuster for approval. Construction of the instrument was commenced in 1914, but owing to the war, it was not completed until late in 1920. In 1919 the writer accepted an appointment with the Admiralty, and as a result, progress with the measurements at Teddington has been slow. Throughout the work Sir Arthur Schuster has rendered most valuable help, and whatever success has been achieved is largely due to him. From the commencement of the investigation the instrument has been called by me the “Schuster Magnetometer.”