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 H.M. Hobson & Co. Ltd. responding to their sketch no. 456 for a telegage and discussing instrument accuracy.
| Identifier | ExFiles\Box 175\4\ img220 | |
| Date | 8th August 1936 | |
| x6003 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Std.5/JH. 8th August, 1936. Messrs. H.M.Hobson & Co.Ltd., 47-55, The Vale, Acton, London. W.5. For the attention of Mr. Seawright, Dear Sirs, We have received your letter of the 7th instant, together with your sketch No. 456 for which we thank you. We will deal numerically with the points mentioned as follows (1) With regard to the proposed telegage shown on sketch 456, we will look into the possibility of using same, but do not anticipate success owing to the large portion of the gauge behind the instrument panel interfering with the rear of other instruments. We do not think that it is vital to obtain the 180° scale which is on our present gauge. (2) With regard to the accuracy of the test instrument loaned to us. This was calibrated by immersing the bulb together with a standard thermometer in a water bath and very slowly raising the temperature of the water from room temperature to 100°C, taking readings every ten degrees, and maintaining the temperature at which the reading was taken from 1 to 2 minutes. Readings were then taken in a similar manner with the water cooling from 100°C. to room temperature. The averages of the two readings at each standard temperature were then taken and the average error over the range from 60° to 100°C. is 1.6°C while the maximum error is 2½°C at 60°C and at 100°C. | ||