Letter from Balfour Stewart, on his paper 'On the great magnetic disturbance which extended from August 28 to September 7, 1859, as recorded by photography at the Kew Observatory' to the Secretary of the Royal Society Author states that should his paper be published in Philosophical Transactions, 'three folded plates' would be required. Subject: Physics [Published in Philosophical Transactions, 1861]. 30 October 1861