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 a supplier discussing the accuracy and physical design of an instrument.
| Identifier | ExFiles\Box 175\4\ img216 | |
| Date | 7th August 1936 | |
| M Rolls-Royce Ltd. Date 7.8.36. Page 2. here, it has proved to be correct at the boiling point. Certain variations may occur lower down in the scale within the limits of accuracy to which it is possible to make this instrument. It would be interesting if you were able to indicate to us the manner of your tests so that we might see that it actually corresponded with our test rig. We generally find that it takes some five minutes for the bulb and its indicating mechanism to build up from room temperature to the correct reading at boiling. Changes of temperature within narrower limits, say from 80°C. to 90°C. are a matter of seconds. We do not know that we could approach an accuracy of greater than ± 2° at temperatures below the boiling point on a production article, but we could work to very much finer limits than this at the boiling point, as the instrument is set from this datum. (b) We regret that it is impossible for us to modify the bulb to come within the dimensions of your adaptor. We know you will appreciate that our bulb is not merely a container for a specific quantity of liquid, but contains mechanism which cannot be reduced below the dimensions which we have now established as satisfactory in practice. We fully appreciate the difficulties of subjecting our instrument to one of your standardised tests, unless it could be accommodated in your present adaptor, but were you to consider proceeding further in the matter, provision would have to be made, as we fear that our bulb must inevitably occupy slightly more room than bulbs of your present water thermometers. We have to thank you for your kindness in passing on the information with regard to the petrol gauge to Mr. West, who has communicated with us, and we are asking him for further particulars, when we shall be only too pleased to furnish a gauge for trial purposes. Yours faithfully, H.{Arthur M. Hanbury - Head Complaints} M.{Mr Moon / Mr Moore} HOBSON (Aircraft & Motor) COMPONENTS, LTD., [Signature] Managing Director. | ||