Plate, graphs of variation of declination magnet at Toronto and St Helena by C [Charles] Chambers Four graphs showing the variation of the declination magnet at Toronto [Canada] and St Helena [British Overseas Territory] throughout the months of the year. Published in paper as Plate XXVI. Subject: Geodesy Published in Philosophical Transactions as 'On the nature of the sun’s magnetic action upon the earth'. Communicated by General [Edward] Sabine. Received by the Royal Society on 30 April 1863. Read 21 May 1863. 30 April 1863