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).
Letter to A.T. Speedometer Co. Ltd. regarding temperature-related errors in their instruments compared to Nemag.
| Identifier | ExFiles\Box 59\2\ Scan229 | |
| Date | 29th August 1933 | |
| 86051 Hs{Lord Ernest Hives - Chair}/Wst.5/MA. August 29th., 1933. The A.T. Speedometer Co.Ltd., Chronos Works, North Circular Road, London, N.W.2. For the attention of Mr.H.R.Buckland. Dear Sir, Replying to your letter of the 16th., which has unfortunately been delayed due to the intervention of holidays we would say that in measuring the percentage temperature error on both the A.T. and the Nemag we ignored the actual calibration in respect to whether the instrument read fast or slow. All we wanted to shew was the intrinsic error of the instrument with rise of temperature, which we shewed was worse with the A.T. than the Nemag. As we expect you use the same alloy for the inductor in each instrument we can only conclude that the induced effects are greater in the A.T. than the Nemag hence rise of resistance in the material accounts for a greater variation in the reading. It would thus appear that a smaller magnet with a weaker control spring would give better results. | ||