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).
Inquiry to The Weston Electrical Instrument Co. about the internal resistance of a milli-voltmeter.
| Identifier | ExFiles\Box 33\4\ Scan154 | |
| Date | 16th March 1918 | |
| X 1782 EFC3/T X.2065 X.1782. 16th March 1918. The Weston Electrical Instrument Co., Audrey House, Ely Place, Holborn, London E.C.1. X.1782. Weston instrument Dear Sirs, With reference to the Weston Direct Reading Milli-voltmeter No.22596 which you have recently standardised for us in conjunction with shunts and volt-box, we should esteem it a great favour if you could tell us accurately the internal resistance of this instrument. The reason why we require this, is that we would like to be able to take direct readings of milli-amperes. One has the impression that if such an instrument is accurate as a milli-voltmeter, it should be still more accurate as a milli-ammeter owing to the fact that the resistance of the instrument might be slightly affected by temperature in the voltmeter case, whereas this would not concern it in the ammeter case. Yours faithfully, FOR ROLLS ROYCE LIMITED. | ||