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).
With an annotated diagram discussing modifications to tremblers to improve the secondary spark.
| Identifier | ExFiles\Box 181\M11\ img068 | |
| Date | 14th August 1917 guessed | |
| -2- Re - Tremblers. iron armature and increasing the inertia of the platinum carrying plate so that although the spring force used is not more than is necessary for length of a good secondary spark, the rate at which the iron armature returns shall be considerably increased. Consult with Mr. Clark and Mr. Hives on this point. The sketches accompanying this memo will explain the modifications I wish you to test, and if you get a satisfactory coil with any of these tremblers will you please send it on to me and I will return you the one from 49-CB. In the meantime please send one or two discs/ larger than standard diameter for the armature to fall back upon. I will put this on 49-CB with certain other modifications. * or a piece of suitable ebonite or other insulation, preferably the white hard material. R.{Sir Henry Royce} [Diagram Annotations] use spring of hard steel wire. remove this post to as near as possible to knife edge. remove from the arm armature the leather and rivets so as to reduce the weight. add weight to this or reduce set until this blade returns to position of rest less quickly than arm armature. | ||