Unpublished paper, 'Description of a method of registering magnetic variations' by Charles Brooke Brooke describes his 'efficient method' of registering magnetic variations, whereby a vertical stream of light issuing through a slit in the copper tube of a camphine lamp is reflected by a concave mirror fixed vertically on the axis of a suspended magnet, and condensed into a focus by a cylindrical lens placed at the distance of about seven feet from the mirror. The luminous image, which shifts its position according to the movements of the magnet, but to a much greater extent, impinges on highly sensitive photographic paper, wound round a horizontal cylinder, which revolves once every twelve hours. Thus, by a combination of the vertical movement of the paper with the horizontal movement of the image, the magnetic curve of variation is distinctly portrayed and registered. Subject: Physics / Magnetism / Meteorology Received 18 June 1846. Whilst the Royal Society declined to publish this paper in full, an abstract of the paper was published in volume 5 of Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London [later Proceedings of the Royal Society] as 'Description of a method of registering magnetic variations'. 16 June 1846