Correspondence and related papers concerning magnetic instruments. The correspondents include G. Forbes, H. Lloyd, F. Beaufort, J.F.W. Herschel, K.F. Gauss, M. Faraday, J.V. Lamont, F. Baily, E. Sabine, C. Brooke and F. Ronalds. The papers include diagrams of the small needles used in the Magnetic Observatory at Munich; a printed 'Account of the Induction Inclinometer and of its Adjustments' by H. Lloyd; a piece of gilt covered paper; a printed paper by W. Snow Harris titled 'New Steering Compass'; and a paper by H. Lloyd 'On the Determination of the intensity of the Earth's Magnetic Force in absolute measure'.