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).
Correspondence from S. Smith & Sons regarding a comparison of a General Filter design with their own.
| Identifier | ExFiles\Box 135\3\ scan0208 | |
| Date | 6th January 1938 | |
| 105 1139 CONTRACTORS TO ADMIRALTY, WAR OFFICE & AIR MINISTRY ENGINEERING AND ALLIED EMPLOYERS' NATIONAL FEDERATION TELEPHONE: GLADSTONE 3333 (20 LINES) TELEGRAMS: SPEEDOFAC, PHONE, LONDON. S. Smith & Sons (Motor Accessories) Ltd CABLES: SPEEDOFAC, LONDON. CODES: MARCONI, COMMERCIAL, BENTLEY'S. BY APPOINTMENT TO HIS MAJESTY THE KING BRANCHES AT PARIS MILAN SYDNEY WELLINGTON AGENCIES AND SERVICE STATIONS THROUGHOUT THE BRITISH EMPIRE AND IN ALL THE PRINCIPAL COUNTRIES SHOWROOMS & DEPOTS 179-185 GT PORTLAND ST LONDON, W.1 26-33, COX ST LIVERY ST, BIRMINGHAM 14A, JACKSONS ROW DEANSGATE MANCHESTER 21, DRURY STREET GLASGOW DUBLIN & BELFAST CRICKLEWOOD WORKS LONDON. N. W. 2 SALES DIRECTOR'S OFFICE. Please quote our reference: S.1. 6th January 1938. W. A.{Mr Adams} Robotham, Esq., Rolls-Royce Limited, DERBY. Dear Mr. Robotham, GENERAL FILTER. Further to your letter of the 30th December, Ref: Rm{William Robotham - Chief Engineer}1/R.{Sir Henry Royce}, I have purposely refrained from replying to this in detail before having had an opportunity for thoroughly investigating the General Filter design with our technical folk. I am extremely obliged to you for so kindly sending along original correspondence with General Filters, Inc., and after submitting this to our filter specialist, Mr. Grose, he has written as per attached memorandum. You will note from this that whilst he readily admits that the General Filter design is advantageous from a point of view of element replacement cost, it compares unfavourably with our own filter on account of the fact that whilst the total surface area of the General is approximately three-quarters of a square foot, in the case of our own the comparison is eleven square feet. You will appreciate that the advantage gained through the medium of cheap elements which have to be replaced every three or four thousand miles is outweighed by the fact that in the case of our own filter the life is approximately four times greater. There is also to be considered the trouble involved in effecting constant changes. | ||