Paper, 'On the power of masses of iron to controul [sic] the attractive force of a magnet' by W [William] Snow Harris 18 manuscript pages including five illustrations showing the placement of iron masses in relation to Harris' apparatus. Subject: Magnetism / Physics Published in volume 121 of Philosophical Transactions as 'On the power of masses of Iron to controul the attractive force of a magnet'. Read 16 June 1831. Abstract published in Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London [later Proceedings of the Royal Society of London], Volume 3, 1837. 28 April 1831