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).
Modifying an annular spark gap, requiring two sets of new interchangeable electrodes.
| Identifier | ExFiles\Box 54\3\ Scan243 | |
| Date | 10th September 1924 | |
| y4645 To RHC.{R. H. Coverley - Production Engineer} from EFC. EFC1/T10.9.24. X+4645 - RE ANNULAR SPARK GAP. Herewith we hand to you our annular spark gap to which you recently made a slight modification. This has not entirely overcome the brush discharging and we are now desirous of trying two other kinds of central and earth electrode, for which purpose it will be necessary to be able to screw in and out the central electrode to effect the change. We require two sets of electrodes as follows:- No.1. Central electrode .087" dia. Earth " Inside dia. .325" No.2. Central electrode .100" dia. Earth. " Inside dia. .312" It is understood that the present central electrode will be sawn off and the hole drilled and tapped to take the new interchangeable electrodes. After trying these it may be necessary to revert to the old dimensions or something near to them, in which case we should ask you to make up a third central electrode element. Please find attached sketch which my assistant has made in connection with this modification. You will appreciate that actual centering of the electrode is essential. EFC. | ||