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).
Test chart recording of electrical performance data with handwritten annotations.
| Identifier | ExFiles\Box 168b\3\ img140 | |
| Date | 11th November 1927 | |
| P-281 10Ylbs 75a.h. 11-11-27 185-6 PQRBDHII-3+4 Average amperes - 6.42 Hours - 9.3 Ampere hours - 59.7 2.34w 558 | ||