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).
Calibration data sheet for a Weston A.C. Milliammeter No. 1068.
| Identifier | ExFiles\Box 33\4\ Scan235 | |
| Date | 10th May 1927 guessed | |
| X.1782 WESTON A.C. MILLIAMMETER NO.1068. Resistance at 16°C = 296.0 ohms. Reading. | M.A. Correction. (%) | True M.A. | D.C. Volts. | Ratio 50~volts reading. | 50~ Volts. | Impedance (ohms). 10 | -1.2 | 9.88 | 2.93 | .3065 | 3.065 | 310 12 | -1.0 | 11.88 | 3.52 | .307 | 3.68 | 310 14 | -.8 | 13.89 | 4.11 | .308 | 4.31 | 310.5 16 | -.7 | 15.89 | 4.70 | .3085 | 4.94 | 311 18 | -.6 | 17.89 | 5.29 | .309 | 5.56 | 311 20 | -.4 | 19.92 | 5.90 | .310 | 6.20 | 311 22 | -.2 | 21.96 | 6.50 | .3105 | 6.83 | 311 24 | Correct. | 24.00 | 7.10 | .3115 | 7.48 | 312 26 | +.2 | 26.05 | 7.70 | ..312 | 8.12 | 312 28 | +.4 | 28.11 | 8.32 | ..3125 | 8.76 | 312 30 | +.6 | 30.18 | 8.93 | ..313 | 9.39 | 312 Reactance at 10 divisions = 92.1 ohms. " " full scale = 98.6 " Inductance at 10 divisions = .29 henry. " " full scale = .31 " EFC. | ||