The magnetic re-survey of the British Isles for the epoch January 1, 1915

The first Magnetic Survey of the British Isles by Rücker and Thorpe was reduced to epoch January 1, 1886, and their more extended survey was reduced to epoch January 1, 1891. For some years a revision of the original survey had been contemplated by Sir Arthur Rücker, but for various reasons did not mature. In the summer of 1913 the Royal Society decided to repeat the survey of the main magnetic features of the British Isles obtained by Rucker and Thorpe, and invited me to undertake the work. It would in any case have been an honour to carry out this work, but to me the honour was increased by the fact that I was a pupil of Sir Arthur Rücker and Sir Edward Thorpe, at the Royal College of Science, when their great undertaking was nearing its completion. The Royal Society desired that I should consult Sir Arthur Rücker with regard to the general scope of the new survey; and, fortunately, Sir Arthur was able at the time to enter into the matter both by correspondence and by personal interview. His view was that the original 200 points used by him and Sir Edward Thorpe should be re-determined and, if possible, marked in some permanent way. He further desired that about 40 new points along the Yorkshire “ridge line” should be chosen.