From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Particulars of an Experimental B type coil.
| Identifier | ExFiles\Box 45\4\ Scan028 | |
| Date | 19th September 1922 | |
| X.4079. 19.9.22. Mr. Clark. Expl. Dept. Please accept particulars of Exp. B type coil: No. of turns on primary 295 No. of turns on Secondary 21560 The core is built up of thicker soft iron wire Dia. on sec. 2" " " prim.13/16" Sgd. W. Gamble. | ||