| Description | Date | Identifier | |
| Letter from Air-Maze Corporation regarding the supply of their air filters and their status as standard equipment. | 8th Dec 1926 | Box 44 \ 1 Scan057 | |
| Promotional brochure for the 'AIR-MAZE' air cleaner, detailing its features, benefits, and performance with a graph. | 8th Dec 1926 | Box 44 \ 1 Scan058 | |
| Informational brochure explaining the principle, construction, and benefits of the Air-Maze air filter. | 15th Dec 1926 | Box 44 \ 1 Scan059 | |
| The function and testing of an experimental Stream-Line filter invented by Dr. Hele-Shaw. | 15th Dec 1926 | Box 44 \ 1 Scan060 | |
| Advertisement leaflet for 'Auto-Klean' gauzeless petrol filters. | 15th Dec 1926 | Box 44 \ 1 Scan061 | |
| Advertisement leaflet for the Auto-Klean strainer, detailing its operational principle, cleaning process, and pricing. | 18th Nov 1926 | Box 44 \ 1 Scan062 | |
| Request to obtain one Zenith Petrol Filter from The Zenith Carburetter Co. Ltd. | 18th Nov 1926 | Box 44 \ 1 Scan063 | |
| Low capacity of a Zenith petrol filter and requesting information on a larger alternative. | 22th Dec 1926 | Box 44 \ 1 Scan064 | |
| Letter from Zenith Carburetters Ltd. clarifying a misunderstanding about a supplied filter and questioning a complaint of it choking. | 28th Dec 1926 | Box 44 \ 1 Scan065 | |
| Correcting the description of an experimental filter obtained from the Zenith Carburetter Co Ltd. | 29th Dec 1926 | Box 44 \ 1 Scan066 | |
| Comparative tests between a Zenith filter and a standard gauze filter for carburettors. | 30th Dec 1926 | Box 44 \ 1 Scan067 | |
| Letter from The Zenith Carburetter Co Ltd. discussing a report on filter tests. | 31th Dec 1926 | Box 44 \ 1 Scan068 | |
| Forwarding a request for a report on fitting a chamois leather filter to a 20HP car due to complaints of petrol stoppages. | 5th Jan 1927 | Box 44 \ 1 Scan069 | |
| The decision not to use chamois leather for petrol filters due to material rot. | 1st Jan 1927 | Box 44 \ 1 Scan070 | |
| Covering memo for blueprints and instructions for a stream line filter. | 8th Jan 1927 | Box 44 \ 1 Scan071 | |
| Instructions from Stream-Line Filter Co. Ltd. for fitting a motor car oil renovator. | 1st Aug 1926 | Box 44 \ 1 Scan072 | |
| Diagram showing the attachment of a Stream-Line filter to a car. | 26th Aug 1926 | Box 44 \ 1 Scan073 | |
| Bench testing of a new 'Zenith' edge filtration petrol filter and suggesting further road tests. | 1st Jan 1927 | Box 44 \ 1 Scan074 | |
| The experimental consideration of an auto cleaner oil filter for potential chassis incorporation. | 10th Jan 1927 | Box 44 \ 1 Scan075 | |
| Arrangement to fit Zenith edge filtration fitments to three cars. | 13th Jan 1927 | Box 44 \ 1 Scan076 | |
| Request to obtain half a dozen Zenith carburetter filters for testing. | 14th Jan 1927 | Box 44 \ 1 Scan077 | |
| The trial of a Zenith petrol filter and its comparison to the standard gauze filter. | 14th Jan 1927 | Box 44 \ 1 Scan078 | |
| Correspondence regarding the experimental fitting of Zenith petrol filters to address fuel line choke issues on 20 HP models and Phantoms. | 18th Jan 1927 | Box 44 \ 1 Scan079 | |
| Letter from Auto-Klean Strainers Ltd. regarding the supply and testing of petrol and oil strainers for motor cars. | 22th Jan 1927 | Box 44 \ 1 Scan080 | |
| Letter from Auto-Klean Strainers Ltd. regarding a new design of petrol filter and potential collaboration. | 22th Jan 1927 | Box 44 \ 1 Scan081 | |
| Arrangement drawing for fitting Zenith petrol filters to 20 HP cars and challenges with the Phantom model. | 24th Jan 1927 | Box 44 \ 1 Scan082 | |
| Sending two Zenith petrol filters to Conduit Street, London. | 24th Jan 1927 | Box 44 \ 1 Scan083 | |
| Modification to a Zenith petrol filter, requesting two glass replacements from the manufacturer. | 26th Jan 1927 | Box 44 \ 1 Scan084 | |
| Proposed modification to a Zenith petrol filter to improve air release. | 26th Jan 1927 | Box 44 \ 1 Scan085 | |
| Drawing illustrating modifications to a Zenith petrol filter, detailing slots in the top baffle and deflector plate. | 26th Feb 1927 | Box 44 \ 1 Scan086 | |
| Letter from Auto Klean Strainers Limited confirming a new filter is being made to address oversized plate spacing issues. | 26th Feb 1927 | Box 44 \ 1 Scan087 | |
| Continuation letter from Auto-Klean Strainers Ltd. regarding arrangements and testing of a filter. | 26th Feb 1927 | Box 44 \ 1 Scan088 | |
| Arrangement drawing of an 'Auto-Klean' petrol strainer with parts list. | 14th Jan 1927 | Box 44 \ 1 Scan089 | |
| Reprint from 'The Motor Boat' magazine describing the Blackman petrol filter for marine engines. | 21th Jan 1927 | Box 44 \ 1 Scan090 | |
| Fitting of a Zenith Filter to chassis GOK/75. | 28th Jan 1927 | Box 44 \ 1 Scan091 | |
| Communication regarding a modification to a Zenith Petrol Filter and the supply of replacement glass parts. | 31th Jan 1927 | Box 44 \ 1 Scan092 | |
| Works order for the supply of a Zenith Filter for a 20-HP chassis. | 2nd Feb 1927 | Box 44 \ 1 Scan093 | |
| Suggestion to obtain a scheme for fitting a Zenith petrol filter to the 20 HP model. | 31th Jan 1927 | Box 44 \ 1 Scan094 | |
| Fitting a Zenith petrol filter to cars to gain experience with it in the hands of customers. | 2nd Feb 1927 | Box 44 \ 1 Scan095 | |
| Instructions on fitting a Zenith petrol filter to a 20 HP car and resolving air bubble issues. | 1st Feb 1927 | Box 44 \ 1 Scan096 | |
| Letter and pattern filter from the Blackman Petrol Filter Co. Ltd. | 1st Feb 1927 | Box 44 \ 1 Scan097 | |
| Promotional advertisement for the Blackman Petrol Filter, detailing features, test results, and testimonials. | 1st Jun 1926 | Box 44 \ 1 Scan098 | |
| Promotional document detailing achievements and testimonials for the Blackman Petrol Filter. | 1st Feb 1927 | Box 44 \ 1 Scan099 | |
| Sales letter from The Blackman Petrol Filter Co Ltd promoting their latest filter with solderless unions. | 1st Feb 1927 | Box 44 \ 1 Scan100 | |
| Continuation letter from The Blackman Petrol Filter Co. Ltd. regarding the testing of a sample on a demonstration car. | 1st Feb 1927 | Box 44 \ 1 Scan101 | |
| Advertising leaflet for Blackman Petrol Filters featuring testimonials from motorsport achievements in 1926-1927. | 17th Jan 1927 | Box 44 \ 1 Scan102 | |
| Advertisement for the Blackman Petrol Filter, detailing its features, benefits, and testimonials. | 21th Jan 1927 | Box 44 \ 1 Scan103 | |
| Micro-examination report on grit extracted from two petrol samples. | 2nd Feb 1927 | Box 44 \ 1 Scan104 | |
| Testing of Autoclean and Zenith filters and a request for a laboratory test. | 14th Feb 1927 | Box 44 \ 1 Scan105 | |
| Outlining the testing procedure for four different types of filters. | 2nd Feb 1927 | Box 44 \ 1 Scan106 | |
| Letter to a supplier discussing the performance of a petrol filter, comparing it to a competitor, and enquiring about a custom-made version. | 18th Feb 1927 | Box 44 \ 1 Scan107 | |
| Confirmation and request for micro-photographs of fluff from a choked jet and particles from various filters. | 2nd Feb 1927 | Box 44 \ 1 Scan108 | |
| Investigation into choked petrol jets caused by fluff, detailing jet sizes and filter gauze analysis. | 25th Feb 1927 | Box 44 \ 1 Scan109 | |
| Analysis of foreign matter causing choked jets and a comparative test of different filters. | 22th Sep 1929 | Box 44 \ 1 Scan110 | |
| The performance, particle analysis, and road testing of a Zenith petrol filter. | 22th Sep 1929 | Box 44 \ 1 Scan111 | |
| The performance and issues with Auto Klean and Chamois leather fuel filters. | 22th Sep 1929 | Box 44 \ 1 Scan112 | |
| Modification to a Zenith filter to resolve an issue with trapped air after cleaning. | 5th Apr 1923 | Box 44 \ 1 Scan113 | |
| Comparison of fluff extracted from a choked low-speed jet with a standard carburetter petrol filter gauze. | 5th Apr 1923 | Box 44 \ 1 Scan114 | |
| Laboratory report with two photomicrographs comparing foreign matter passing through different filters. | 5th Apr 1923 | Box 44 \ 1 Scan115 | |
| Blueprint detailing modifications to a Zenith petrol filter, showing slot dimensions and a dismantled view. | 1st Mar 1927 | Box 44 \ 1 Scan116 | |
| Cover note forwarding a letter from the Blackman Petrol Filter Co. Ltd. regarding a filter. | 26th Feb 1927 | Box 44 \ 1 Scan117 | |
| Letter from The Blackman Petrol Filter Co Ltd proposing their new petrol filter for adoption. | 24th Feb 1927 | Box 44 \ 1 Scan118 | |
| Advertisement leaflet for The Blackman Petrol Filter, detailing its features, price, and customer testimonials. | 1st Jun 1926 | Box 44 \ 1 Scan119 | |
| Promotional document showcasing testimonials and race wins for the Blackman Petrol Filter. | 1st Mar 1927 | Box 44 \ 1 Scan120 | |
| Letter to Messrs. The AutoKlean Strainers Ltd. arranging a meeting to discuss filters. | 1st Mar 1927 | Box 44 \ 1 Scan121 | |
| Letter from Auto Klean Strainers Limited regarding a meeting to discuss and trial a new filter. | 2nd Mar 1927 | Box 44 \ 1 Scan122 | |
| Letter from Auto Klean Strainers Limited regarding oil strainers for a Morris chassis and potential aeroplane purposes. | 2nd Mar 1927 | Box 44 \ 1 Scan123 | |
| Letter confirming a telegram and rescheduling an appointment due to illness. | 3rd Mar 1927 | Box 44 \ 1 Scan124 | |
| Letter from Auto Klean Strainers Limited confirming a telegram about a cancelled appointment due to illness. | 3rd Mar 1927 | Box 44 \ 1 Scan125 | |
| Letter from Auto Klean Strainers Limited postponing Mr Stuart's visit to Derby due to illness. | 7th Mar 1927 | Box 44 \ 1 Scan126 | |
| Correspondence and a tool from the Blackman Petrol Filter Co. Ltd. | 7th Mar 1927 | Box 44 \ 1 Scan127 | |
| Zenith Filters, requisitions from Cricklewood, and the potential to fit them for customers. | 8th Mar 1927 | Box 44 \ 1 Scan128 | |
| Trial and potential standardisation of Zenith filters on a 20 HP car. | 9th Mar 1927 | Box 44 \ 1 Scan129 | |
| Letter from Auto Klean Strainers Limited arranging a meeting to discuss a filter. | 12th Mar 1927 | Box 44 \ 1 Scan130 | |
| The blocking of a Zenith petrol filter, particularly when running on reserve fuel, and a proposal for further investigation. | 14th Apr 1927 | Box 44 \ 1 Scan131 | |
| Letter to The Auto Klean Strainers Ltd. arranging a meeting with their Mr. Stuart. | 15th Mar 1927 | Box 44 \ 1 Scan132 | |
| Technical leaflet describing the function and specifications of the 'Auto-Klean' Strainer, type P.S. | 15th Mar 1927 | Box 44 \ 1 Scan133 | |
| Advertisement for Auto-Klean Strainers, a gauzeless petrol filter that can be cleaned while the engine is running. | 16th Mar 1927 | Box 44 \ 1 Scan134 | |
| Letter from Auto Klean Strainers Limited confirming a meeting arrangement for Mr. Stuart. | 16th Mar 1927 | Box 44 \ 1 Scan135 | |
| Letter from Auto Klean Strainers Limited regarding the testing and supply of petrol and lubricating strainers. | 24th Mar 1927 | Box 44 \ 1 Scan136 | |
| Blueprint for an Auto Klean Strainer, detailing its dimensions, materials, and capacity. | 13th Apr 1927 | Box 44 \ 1 Scan137 | |
| Letter to Auto Klean Strainers Ltd. regarding the testing of petrol filters and requesting a 'K' type oil strainer on loan. | 13th Apr 1927 | Box 44 \ 1 Scan138 | |
| Letter from a supplier regarding the supply of petrol filters and a 'K' type strainer for trial purposes. | 14th Apr 1927 | Box 44 \ 1 Scan139 | |
| Letter discussing foreign matter in a petrol filter, leakage on shock absorbers, and testing of leather packings. | 28th Apr 1927 | Box 44 \ 1 Scan140 | |
| Letter from Auto Klean Strainers Limited regarding the despatch of a 'K' type lubricating strainer for examination and testing. | 2nd May 1927 | Box 44 \ 1 Scan141 | |
| Letter from the Experimental Department regarding petrol starvation at high speeds, and arranging a test. | 2nd May 1927 | Box 44 \ 1 Scan142 | |
| Letter from The Zenith Carburetter Co. Ltd. requesting a report on petrol filter tests. | 6th May 1927 | Box 44 \ 1 Scan143 | |
| Letter to the Zenith Carburettor Company regarding issues with filter choking during road and bench tests. | 9th May 1927 | Box 44 \ 1 Scan144 | |
| Letter from Zenith Carburetter Co. Ltd. regarding an increase in the area of a filter element. | 10th May 1927 | Box 44 \ 1 Scan145 | |
| Sample plate filter received from the Zenith Carburetter Co for the Experimental Department. | 21th May 1927 | Box 44 \ 1 Scan146 | |
| Despatch of a Zenith petrol filter to be exchanged for a later type. | 24th May 1927 | Box 44 \ 1 Scan147 | |
| Letter to The Zenith Carb. Co. Ltd. regarding the return of a filter with a small plate element and a request to exchange it for a later type with a large area for testing. | 24th May 1927 | Box 44 \ 1 Scan148 | |
| Letter from The Zenith Carburetter Co. Ltd. regarding the exchange of a returned element for one with a larger area. | 26th May 1927 | Box 44 \ 1 Scan149 | |
| Letter to The Zenith Carburettor Company regarding an incorrect petrol filter element. | 31th May 1927 | Box 44 \ 1 Scan150 | |
| Letter from Zenith Carburetter Co. Ltd. discussing petrol filter specifications. | 1st Jun 1927 | Box 44 \ 1 Scan151 | |
| Letter from Zenith Carburetter Co. clarifying a misunderstanding regarding the diameter of discs and filters. | 1st Jun 1927 | Box 44 \ 1 Scan152 | |
| The standardization of the Zenith petrol filter for the 20 HP car, including specifications for plate gap and weight. | 1st Jun 1927 | Box 44 \ 1 Scan153 | |
| Letter to the Zenith Carburettor Company regarding filter specifications and a request for weight reduction. | 2nd Jun 1927 | Box 44 \ 1 Scan154 | |
| Letter to Zenith Carburetter Co. Ltd. requesting the type number of a petrol filter suitable for a 20 HP chassis. | 3rd Jun 1927 | Box 44 \ 1 Scan155 | |
| Letter from Zenith Carburetter Co. Ltd. discussing the weight and diameter of a disc. | 4th Jun 1927 | Box 44 \ 1 Scan156 | |
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