Joule meter by Ferranti, Hollinwood, England. Constructed for display by Griffin and George Ltd. 'Made in Great Britain' Joule meter by Ferranti 1950-1960
Output transformer in original box, type OPM 6 (C), Ferranti Ltd, Holinwood, Manchester. Made 1915. Ferranti transformer 1915
Joulemeter by Ferranti Ltd., supplied by Griffin and George Ltd. Joulemeter by Ferranti Ltd. 1967-1983