Paper, 'Transformers' by John Perry Perry writes: 'In a transformer with many circuits, of resistances in ohms and numbers of turns R1, N1, R2, N2, &c.; let the currents at any instant be C1, C2, &c., amperes, and let the independent electromotive forces e1, e2, &c., volts be maintained in them; let I be the total magnetic induction which threads through all the circuits (108 C. G. S. units being taken as the unit of induction).' Annotations in pencil and ink. Subject: Physics / Electricity Received 23 March 1892. Read 12 May 1892. A version of this paper was published in volume 51 of the Proceedings of the Royal Society as 'Transformers'. 1892