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).
Graph showing the relation between sparking voltage and the diameter of the central electrode.
| Identifier | ExFiles\Box 164\5\ img012 | |
| Date | 12th June 1924 | |
| CURVE N° 2089 REF 24 G/D 12-6-24 INITIAL IONISATION PROBABLY COMMENCED CONCENTRIC GAPS MAGNETO SINE WAVE RELATION BETWEEN SPARKING VOLTAGE & DIA. OF CENTRAL ELECTRODE DIA. OF HOLE = WIRE DIA. x 5 TESTS TAKEN BY N.P.L. 28-5-18 KILO VOLTS GAUGE OF WIRE DIA. OF WIRE M/M | ||