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 from Cambridge Instrument Company regarding a special radiator thermometer with an electric contact at 97°C.
| Identifier | ExFiles\Box 175\4\ img033 | |
| Date | 31th May 1926 | |
| x3875 TELEGRAMS: INSTRUMENT, CAMBRIDGE. CODES: A.B.C. (5TH AND 6TH EDITIONS); WESTERN UNION; BENTLEY'S. TELEPHONE: CAMBRIDGE No. 615. CAMBRIDGE INSTRUMENT COMPANY, LIMITED, HEAD OFFICE AND SHOWROOMS; 45, GROSVENOR PLACE, LONDON, S.W.1. WORKS: LONDON AND CAMBRIDGE. REGD. TRADE MARK. MANUFACTURERS OF MECHANICAL & ELECTRICAL INSTRUMENTS OF PRECISION. YOUR REF....................... CAMBRIDGE, ENGLAND. IN REPLY PLEASE QUOTE CCM/MW 31st May 1926. W. A.{Mr Adams} Robotham, Esq., Messrs. Rolls-Royce Ltd., Derby. Dear Sir, We are sending you today the special radiator thermometer fitted with an electric contact at 97°C. In order that this contact shall not affect the readings while still using your standard scale, the contact is made on to a light platinum spring. The section of this platinum spring necessarily has to be small. It is not, therefore, safe to pass a current exceeding ½ amp. through the contact. This, however, is ample current to work a buzzer or to light a 6-watt lamp on a 12-volt circuit. If you want more current than this it will be necessary to fit a stiffer piece of platinum, and then it will be necessary to reduce the length of the last division on the scale, i.e. the division between 95 and 100, as the effect of a stronger contact would be to close up the last 3° of the scale. We trust, however, you will find the instrument satisfactory as it is. Yours faithfully, FOR CAMBRIDGE INSTRUMENT CO. LTD. | ||