Unpublished letter, regarding terrestrial magnetism from R Wolf to Edward Sabine Wolf describes his observations on the connections between sunspots and variations in terrestrial magnetism. Annotations in pencil. Marked on front as 'Proc [Proceedings]'. Subject: Physics / Magnetism Communicated by Sabine. Written by Wolf in Zurich. Whilst the Royal Society declined to publish this paper in full, an abstract of the paper was published in volume 8 of Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London [later Proceedings of the Royal Society] as 'Extract of a letter addressed to General Sabine, R. A. Treas. and V. P. R. S., by M. R. Wolf, dated Zurich, March 7, 1857. Communicated by Gen. Sabine'. 7 March 1857