| Description | Date | Identifier | |
| Watford IS12 Magneto returned from the makers with improved electrical performance. | 23th Jul 1930 | Box 43 \ 4 Scan297 | |
| Approval and supply of magnetos from the Watford Company for aero engines. | 5th Sep 1930 | Box 43 \ 4 Scan298 | |
| Air Ministry letter granting airworthiness approval for Watford S.F.12-2 magnetos fitted to F XIV MS engines. | 1st Aug 1930 | Box 43 \ 4 Scan299 | |
| Return of two Watford SP.12-2 magnetos. | 1st Sep 1930 | Box 43 \ 4 Scan300 | |
| Letter to North & Sons, Ltd. regarding the return of two magnetos for fitting new armatures for an 'H' engine type test. | 11th Sep 1930 | Box 43 \ 4 Scan301 | |
| Acceptance test log for Watford Aero Magnetos to an abridged specification. | 23th Oct 1930 | Box 43 \ 4 Scan302 | |
| Performance improvements of two Watford IS12 aero magnetos following the replacement of their armature windings. | 23th Oct 1930 | Box 43 \ 4 Scan303 | |
| Query regarding the differences in screening, leads, and interchangeability between a 'Watford' Magneto and a standard B.I.H. machine. | 24th Oct 1930 | Box 43 \ 4 Scan304 | |
| Comparison of the Watford I.S.12 magneto against the standard B.T.H. machine regarding interchangeability. | 25th Oct 1930 | Box 43 \ 4 Scan305 | |
| List of Watford Aero Magnetos with their types, serial numbers, and remarks on use or condition. | 23th Oct 1930 | Box 43 \ 4 Scan306 | |
| List of 'R' aero engine magnetos with their part numbers, remarks, and engine allocation. | 23th Oct 1930 | Box 43 \ 4 Scan307 | |
| On the performance improvements of Watford magnetos after being fitted with new armatures for an 'H' engine test. | 31th Oct 1930 | Box 43 \ 4 Scan308 | |
| The upgrading of a pair of Watford Magnetos, type IS.12, to balance their performance for an engine test. | 1st Nov 1930 | Box 43 \ 4 Scan309 | |
| The interchangeability of a Watford I.S. 12 magneto with a B.T.H. machine. | 5th Nov 1930 | Box 43 \ 4 Scan310 | |
| Letter to Messrs. North & Sons Ltd. regarding a discrepancy in the safety gap of a refurbished Watford IS.12 Magneto. | 17th Nov 1930 | Box 43 \ 4 Scan311 | |
| Letter from North & Sons, Ltd. regarding an error in setting the safety gaps on Watford IS.12 magnetos. | 18th Nov 1930 | Box 43 \ 4 Scan312 | |
| The testing and modification of Watford IS.12 magnetos for the F.39 engine. | 20th Nov 1930 | Box 43 \ 4 Scan313 | |
| Handing over of updated Watford magnetos for fitting to an F.39 engine for type testing. | 3rd Dec 1930 | Box 43 \ 4 Scan314 | |
| The replacement of B.T.H. magnetos with interchangeable Watford magnetos. | 15th Dec 1930 | Box 43 \ 4 Scan315 | |
| Cross-reference note for further information on the Watford SP.12-2 magneto. | 31th Dec 1930 | Box 43 \ 4 Scan316 | |
| Letter from the American branch discussing eight-cylinder engine development and the viability of the 40/50 car in the US market. | 9th Dec 1926 | Box 43 \ 4 Scan317 | |
| Car design principles concerning engine configuration and dimensions to adapt to modern traffic conditions. | 9th Dec 1926 | Box 43 \ 4 Scan318 | |
| Engine design, moment of inertia, and a potential V8 engine, with comparisons to a Packard. | 9th Dec 1926 | Box 43 \ 4 Scan319 | |
| Chassis length and shortening the bonnet on an eight-cylinder car. | 29th Dec 1926 | Box 43 \ 4 Scan320 | |
| Eight-cylinder car and the market trend towards smaller vehicles due to traffic congestion. | 29th Dec 1926 | Box 43 \ 4 Scan321 | |
| Car design principles, comparing engine types and dimensions for future models, particularly contrasting V-eight and straight-eight engines. | 29th Dec 1926 | Box 43 \ 4 Scan322 | |
| Challenges and potential designs for a V-eight engine, including comparisons with competitor models like the Packard. | 6th Oct 1929 | Box 43 \ 4 Scan323 | |
| Trial results and characteristics of 8-cylinder V-type engines. | 6th Oct 1929 | Box 43 \ 4 Scan324 | |
| Development of a 12-cylinder car, comparing competitors and deciding to build their own engine. | 4th Mar 1931 | Box 43 \ 4 Scan325 | |
| Investigation into fitment and distribution problems with an eight-cylinder Vee engine, with comparisons to other engines. | 21th Apr 1931 | Box 43 \ 4 Scan326 | |
| Comparative table of engine specifications for various makes of cars with 12 and 16 cylinder engines. | 8th May 1931 | Box 43 \ 4 Scan327 | |
| On future engines, proposing a 12-cylinder model for first-class luxury cars. | 8th May 1931 | Box 43 \ 4 Scan328 | |
| Development of smaller car models and engine sizes. | 18th Jun 1931 | Box 43 \ 4 Scan329 | |
| List of British cars with 16 to 18HP rating, detailing their specifications and price. | 18th Jun 1931 | Box 43 \ 4 Scan330 | |
| List of foreign cars from 16 to 18 HP rating with specifications and prices. | 24th Jun 1931 | Box 43 \ 4 Scan331 | |
| Various engine configurations (6-cylinder, straight-8, V-8, V-12) and future design directions. | 24th Jun 1931 | Box 43 \ 4 Scan332 | |
| Material choices for engine design, comparing cast iron and aluminum, and the potential use of Austenitic liners. | 2nd Jul 1931 | Box 43 \ 4 Scan333 | |
| Merits of a 6-cylinder engine versus proposed 8 and 12-cylinder engines. | 2nd Jul 1931 | Box 43 \ 4 Scan334 | |
| Developments in 12-cylinder engines, automatic clutches, and vibration damping in US cars. | 30th Jan 1932 | Box 43 \ 4 Scan335 | |
| Comparison table of specifications for 12-cylinder engines from various car manufacturers. | 1st Feb 1932 | Box 43 \ 4 Scan336 | |
| Torsional vibrations comparing the 6th order vibration on a Phantom II engine with a 60 Vee 6250 cc engine. | 24th Feb 1932 | Box 43 \ 4 Scan337 | |
| Severity and amplitude of 6th order vibration in a 12-cylinder engine. | 24th May 1932 | Box 43 \ 4 Scan338 | |
| Testing of a 12-cylinder engine for torsional vibration, particularly for use in speed boats for Sir Malcolm Campbell. | 11th May 1932 | Box 43 \ 4 Scan339 | |
| Technical merits and drawbacks of a narrow-angle V8 engine design. | 15th Dec 1933 | Box 43 \ 4 Scan340 | |
| Confirming the dispatch of an Ideal Double Filter and Filler from Wallis, Sutton & Wilson of Birmingham. | 18th Feb 1920 | Box 44 \ 1 Scan001 | |
| Letter from Cox Carburetters Limited regarding their ATMOS Patent Filter. | 20th May 1920 | Box 44 \ 1 Scan002 | |
| Instruction leaflet for the Cox 'Atmos' Separator Filter, with handwritten notes. | 20th May 1920 | Box 44 \ 1 Scan003 | |
| Installation and operation instructions for a Cox 'Atmos' separator filter. | 16th Jun 1920 | Box 44 \ 1 Scan004 | |
| Requesting a report on the test of a 'Universal' petrol filter sent by the Walter Scott Co. | 16th Jun 1920 | Box 44 \ 1 Scan005 | |
| Sales letter from Walter Fricke in Berlin offering the 'Filtrator' dust-removing apparatus for explosion motors. | 25th Jun 1920 | Box 44 \ 1 Scan006 | |
| Technical advertisement for the 'Filtrator' air filter by Walter Fricke of Berlin. | 25th Jun 1920 | Box 44 \ 1 Scan007 | |
| Advertisement in German for an automotive filter called 'FILTRATOR'. | 29th Jul 1920 | Box 44 \ 1 Scan008 | |
| German promotional document for the 'Filtrator' engine air filter, including a price and specifications table. | 29th Jul 1920 | Box 44 \ 1 Scan009 | |
| Terms of delivery for a product named 'Filtrator' from Walter Fricke, Berlin. | 13th Nov 1910 | Box 44 \ 1 Scan010 | |
| Sales letter from C.P. Preston Company offering a Giusti Gauseless Filter & Separator for testing purposes. | 13th Nov 1910 | Box 44 \ 1 Scan011 | |
| Continuation sheet of a letter from The C. P. Preston Company to J. Wormald. | 22th Nov 1920 | Box 44 \ 1 Scan012 | |
| Letter regarding a sample 'Giusti Gausel-ea Filter and Separator' received after the Motor Exhibition. | 22th Nov 1920 | Box 44 \ 1 Scan013 | |
| Letter proposing to send a 'Giusti Gauzeless Filter and Separator' for testing and demonstration purposes. | 29th Nov 1920 | Box 44 \ 1 Scan014 | |
| Product guarantee certificate for the Saunders Petrol Saver from The C.P. Preston Co., Ltd. | 11th Jan 1914 | Box 44 \ 1 Scan015 | |
| Advertisement leaflet for the 'Giusti' gauzeless petrol filter and separator. | 11th Jan 1914 | Box 44 \ 1 Scan016 | |
| Leaflet describing the scientific principle, construction, and fitting of the Giusti Gauzeless Filter and Separator. | 3rd Dec 1920 | Box 44 \ 1 Scan017 | |
| Letter from C.P. Preston Company Ltd. to Rolls-Royce acknowledging their letter regarding the Giusti Gauzeless Petrol Filter. | 3rd Dec 1920 | Box 44 \ 1 Scan018 | |
| To the Accountancy Department regarding an unsolicited invoice for a filter sent for trial. | 1st Dec 1920 | Box 44 \ 1 Scan019 | |
| Letter to C.P. Preston Co. Ltd. regarding a petrol filter submitted for evaluation by the Experimental Department. | 1st Dec 1920 | Box 44 \ 1 Scan020 | |
| Follow-up letter from C.P. Preston Co. Ltd enquiring about the test results for their 'Giusti Gauzeless Filter' and Separator. | 14th Jan 1921 | Box 44 \ 1 Scan021 | |
| Follow-up letter to C.P. Preston Co. Ltd. regarding the time needed to test a filter before providing an opinion on its quality. | 15th Jan 1921 | Box 44 \ 1 Scan022 | |
| Cover note regarding correspondence with C.P. Preston Company. | 15th Jan 1921 | Box 44 \ 1 Scan023 | |
| Letter to The C.P. Preston Co.Ltd. acknowledging receipt of a petrol filter for evaluation by the Experimental Department. | 1st Dec 1920 | Box 44 \ 1 Scan024 | |
| Letter from C.P. Preston Company Ltd. regarding the testing of their Saunders Petrol Saver filter. | 16th Jan 1921 | Box 44 \ 1 Scan025 | |
| New petrol filter for cars and aero engines, presented by Sir Egerton Graeme. | 19th Jul 1923 | Box 44 \ 1 Scan026 | |
| Clarifying a misunderstanding regarding petrol filter samples for Sir Egerton H. Graeme. | 15th Aug 1923 | Box 44 \ 1 Scan027 | |
| Update on a petrol filter experiment sent by Sir Egerton Graeme. | 18th Dec 1923 | Box 44 \ 1 Scan028 | |
| Evaluation of petrol filters supplied by Sir Egerton Graeme, recommending against their standard use due to design flaws. | 28th Dec 1923 | Box 44 \ 1 Scan029 | |
| The return of petrol filters to a customer, Sir Egerton Graeme. | 31th Dec 1923 | Box 44 \ 1 Scan030 | |
| The return of two loaned petrol filters to Sir Egerton Graeme. | 17th Jan 1924 | Box 44 \ 1 Scan031 | |
| Letter to Sir Egerton Graeme concerning the return of two filters loaned for experimental tests. | 17th Jan 1924 | Box 44 \ 1 Scan032 | |
| Issues with Sir E.H. Graeme's filters, which were found to leak petrol during testing. | 2nd Feb 1924 | Box 44 \ 1 Scan033 | |
| Despatch of 4 unions for petrol filters to Sir Egerton Graeme. | 2nd Feb 1924 | Box 44 \ 1 Scan034 | |
| Letter to Sir Egerton Graeme regarding the dispatch of 4 unions for petrol filters. | 12th Feb 1924 | Box 44 \ 1 Scan035 | |
| Acknowledgement of a memo and the safe receipt of Lympid filters. | 20th Feb 1924 | Box 44 \ 1 Scan036 | |
| Forwarding a letter and device from Auto-Klean Strainers Ltd for evaluation. | 17th Apr 1924 | Box 44 \ 1 Scan037 | |
| Letter from Auto-Klean Strainers Ltd concerning the supply of two 'P' type strainers for evaluation. | 14th Apr 1924 | Box 44 \ 1 Scan038 | |
| Advertising brochure for the Bassick Gas-co-lator visible gasoline filter. | 14th Apr 1924 | Box 44 \ 1 Scan039 | |
| Advertisement for the Bassick Gas-co-lator, a visible gasoline filter designed to eliminate carburetor trouble. | 23th Feb 1925 | Box 44 \ 1 Scan040 | |
| Comparing a 'Milegal Petrol Filler' to the currently used 'Ligall Petrol Filler'. | 23th Feb 1925 | Box 44 \ 1 Scan041 | |
| Correspondence from 'Milegal Petrol Filler' regarding the durability of their petrol pourer and cork float. | 27th Feb 1925 | Box 44 \ 1 Scan042 | |
| Letter from Milegal Meters Ltd. advising on cleaning a gauze and the type of tubing being fitted. | 25th Feb 1925 | Box 44 \ 1 Scan043 | |
| Advertisement for the 'Twentisec' Petrol Pourer, a device for quickly transferring fuel. | 10th Jul 1912 | Box 44 \ 1 Scan044 | |
| Promotional leaflet and correspondence regarding the 'TWENTISEC' petrol pourer. | 10th Jul 1912 | Box 44 \ 1 Scan045 | |
| Suggesting the trial of an Auto-Klean strainer. | 26th Oct 1925 | Box 44 \ 1 Scan046 | |
| Promotional brochure for the Auto-Klean Strainer, detailing its features, guarantee, and price. | 26th Oct 1925 | Box 44 \ 1 Scan047 | |
| Promotional leaflet explaining the function, benefits, and technical specifications of the Auto-Klean Strainer with a cross-sectional diagram. | 26th Oct 1925 | Box 44 \ 1 Scan048 | |
| Advertisement for Auto-Klean gauzeless petrol filters from Beldam Asbestos Company. | 26th Oct 1925 | Box 44 \ 1 Scan049 | |
| Product information sheet for Auto-Klean Strainers, detailing their operation and features. | 26th Oct 1925 | Box 44 \ 1 Scan050 | |
| The performance of Auto-Klean strainers on a test bench and a 40/50 HP car. | 26th Oct 1925 | Box 44 \ 1 Scan051 | |
| Instrument strainer fault and petrol leakage from a filter. | 16th Nov 1925 | Box 44 \ 1 Scan052 | |
| The purchase of a petrol filter from Tecalemit Ltd. | 18th Nov 1926 | Box 44 \ 1 Scan053 | |
| Petrol filters, comparing chamois leather to gauze and mentioning a new 'edge' filtration system being tested. | 12th Dec 1926 | Box 44 \ 1 Scan054 | |
| Letter to a customer about fitting a fuel filter and the problems associated with using chamois leather with certain fuels like Benzole. | 2nd Dec 1926 | Box 44 \ 1 Scan055 | |
| Cancellation of an order for a Tecalemit Filter as its chamois leather is not suitable for benzol. | 3rd Dec 1926 | Box 44 \ 1 Scan056 | |
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