| Description | Date | Identifier | |
| Advertisement leaflet for the ARIS High Tension Connector. | 8th Mar 1920 | Box 33 \ 3 Scan054 | |
| Advertisement for Aris Sparking Plugs, detailing different models and their construction. | 8th Mar 1920 | Box 33 \ 3 Scan055 | |
| Advertising leaflet for the 'ARIS' Sparking Plug, detailing its features and benefits. | 8th Mar 1920 | Box 33 \ 3 Scan056 | |
| Advertisement for a High Tension Connector from The British Aris Sparking Plug Company. | 8th Mar 1920 | Box 33 \ 3 Scan057 | |
| Product information sheet for a high tension sparking plug connector. | 8th Mar 1920 | Box 33 \ 3 Scan058 | |
| Advertisement and description for the 'ARIS' Sparking Plug. | 8th Mar 1920 | Box 33 \ 3 Scan059 | |
| Advertisement for ARIS sparking plugs, showing various models and a detailed cross-section. | 8th Mar 1920 | Box 33 \ 3 Scan060 | |
| Letter from The British Aris Sparking Plug Co. Ltd. promoting their spark plugs and high-tension wire connectors. | 8th Mar 1920 | Box 33 \ 3 Scan061 | |
| Letter from a supplier offering to send samples of Motor Car Plugs. | 12th Mar 1920 | Box 33 \ 3 Scan062 | |
| Letter concerning an enquiry for motor car plugs from the Federal Company of the States. | 23th Mar 1920 | Box 33 \ 3 Scan063 | |
| Letter from The Forward Sparking Plug Co. regarding the supply and testing of 'E' type spark plugs. | 26th Mar 1920 | Box 33 \ 3 Scan064 | |
| Letter regarding the dispatch and comparative performance of various spark plug brands, including Herz, A.C., and Champion. | 22th May 1920 | Box 33 \ 3 Scan065 | |
| To F.H. Royce discussing different types of spark plugs and their performance. | 22th May 1920 | Box 33 \ 3 Scan066 | |
| Development of new spark plugs by the Flint Company and the American Bosch Co. | 22th May 1920 | Box 33 \ 3 Scan067 | |
| The testing of 'Vallier' Spark Plugs from Messrs. Parker & French. | 1st Jun 1920 | Box 33 \ 3 Scan068 | |
| Suitability of a sample American-made, single-point plug for the chassis. | 28th Jun 1920 | Box 33 \ 3 Scan069 | |
| Letter from an agent offering 'Express Spark Plugs' for trial and sale for use in aviation engines. | 24th Jun 1920 | Box 33 \ 3 Scan070 | |
| Bureau of Standards report on an endurance test conducted on Duffy 'Air-Line' spark plugs. | 17th Aug 1917 | Box 33 \ 3 Scan071 | |
| Advertisement for Express spark-plugs, highlighting their performance in oily motors. | 24th Jul 1920 | Box 33 \ 3 Scan072 | |
| Allocation of work on magnetos, ignition, and sparking plugs. | 24th Jul 1920 | Box 33 \ 3 Scan073 | |
| Letter regarding the sending of six Bougie Gilardoni Sparking Plugs for testing. | 27th Jul 1920 | Box 33 \ 3 Scan074 | |
| Letter arranging for six Gilardoni sparking plugs to be sent for testing. | 23th Jul 1920 | Box 33 \ 3 Scan075 | |
| Forwarding of A.C. 'Titan' single-point sparking plugs for testing. | 29th Jul 1920 | Box 33 \ 3 Scan076 | |
| Authorising an order for 5000 sparking plugs and agreeing to increase the minimum order number. | 10th Aug 1920 | Box 33 \ 3 Scan077 | |
| Suitability of Lodge mica ignition plugs compared to porcelain and K.L.G. types. | 10th Sep 1920 | Box 33 \ 3 Scan078 | |
| Cleanability and design of various spark plugs. | 10th Sep 1920 | Box 33 \ 3 Scan079 | |
| Inspection of the 1.EX engine, detailing issues with ignition and valve clearance at low speeds. | 10th Sep 1920 | Box 33 \ 3 Scan080 | |
| Method for cleaning sooted Lodge sparking plugs. | 10th Sep 1920 | Box 33 \ 3 Scan081 | |
| Minute from a conference in Derby regarding the decision to use two sources of supply for batteries and sparking plugs. | 16th Sep 1920 | Box 33 \ 3 Scan082 | |
| Ongoing testing and evaluation of ignition plugs, specifically the Lodge C.9, and the strategy for sourcing them. | 4th Oct 1920 | Box 33 \ 3 Scan083 | |
| Use and comparison of American Champion and Lodge spark plugs. | 4th Oct 1920 | Box 33 \ 3 Scan084 | |
| Ripaults Oleo Plugs being used in the winning machine of the Gordon-Bennett Cup race. | 11th Oct 1920 | Box 33 \ 3 Scan085 | |
| Points for attention following an American visit, concerning rear springs, steering pivots, and ignition issues. | 11th Nov 1920 | Box 33 \ 3 Scan086 | |
| Unsatisfactory spark plugs and magneto failures, suggesting alternative parts and design changes. | 11th Nov 1920 | Box 33 \ 3 Scan087 | |
| Chassis 39-TW, discussing improvements to ignition plugs and condensers. | 12th Nov 1920 | Box 33 \ 3 Scan088 | |
| Results of further tests for leaky sparking plugs. | 22th Nov 1920 | Box 33 \ 3 Scan089 | |
| Various points following a visit to America, covering ignition, magnetos, and other vehicle components. | 22th Nov 1920 | Box 33 \ 3 Scan090 | |
| Article from 'The Motor' magazine about the construction of modern sparking plugs using mica. | 29th Dec 1920 | Box 33 \ 3 Scan091 | |
| Article from 'The Motor' magazine describing the manufacturing process and testing of mica spark plugs, specifically the detachable 'G' type K.L.G. plug. | 29th Dec 1920 | Box 33 \ 3 Scan092 | |
| Instruction note comparing the performance of different spark plug brands. | 3rd Jan 1921 | Box 33 \ 3 Scan093 | |
| Requesting information on the position of plugs in an engine, whether pocket or central. | 4th Jan 1921 | Box 33 \ 3 Scan094 | |
| Test report comparing the performance of various spark plugs under different conditions. | 17th Jan 1921 | Box 33 \ 3 Scan095 | |
| Test log for various spark plugs, detailing results of mixture, insulation, oiling, and pre-ignition tests. | 20th Jan 1921 | Box 33 \ 3 Scan096 | |
| Returning Heath spark plugs after testing revealed them to be the worst performing. | 13th Jan 1921 | Box 33 \ 3 Scan097 | |
| Proposed new sparking plug and its claimed advantages. | 21th Jan 1921 | Box 33 \ 3 Scan098 | |
| Unsatisfactory testing results of Heath spark plugs in cars and aero engines. | 3rd Feb 1921 | Box 33 \ 3 Scan099 | |
| The procedures for testing various makes of sparking plugs. | 1st Feb 1921 | Box 33 \ 3 Scan100 | |
| Test report on various types of spark plugs. | 9th Feb 1921 | Box 33 \ 3 Scan101 | |
| Results of tests on various spark plugs, providing a ranking and a recommendation for purchase. | 9th Feb 1921 | Box 33 \ 3 Scan102 | |
| Forwarding a letter from Heath Plugs Ltd. and discussing associated test reports. | 2nd Feb 1921 | Box 33 \ 3 Scan103 | |
| Letter and test reports for Heath Plugs. | 11th Feb 1921 | Box 33 \ 3 Scan104 | |
| Letter from Heath Plugs, Limited, defending their spark plug design against claims of sooting and oiling up. | 9th Feb 1921 | Box 33 \ 3 Scan105 | |
| Page 2 of a letter from Heath Plugs Ltd. regarding the superiority of their sparking plugs. | 10th Dec 1930 | Box 33 \ 3 Scan106 | |
| Inclusion of a slow running test for sparking plugs and its long-term reliability. | 4th Feb 1921 | Box 33 \ 3 Scan107 | |
| Comparing different types of sparking plugs. | 16th Feb 1921 | Box 33 \ 3 Scan108 | |
| Conclusion to standardise Champion (Canadian make) and Mercury (Birmingham make) components for cars. | 16th Feb 1921 | Box 33 \ 3 Scan109 | |
| Requesting an update on the action taken with reference to a sparking plug. | 21th Feb 1921 | Box 33 \ 3 Scan110 | |
| Performance and recommendation of various sparking plug brands such as Champion, Mercury, and Lodge. | 2nd Feb 1921 | Box 33 \ 3 Scan111 | |
| Proposal for a cost-saving plug repair and exchange system for Mercury plugs. | 2nd Feb 1921 | Box 33 \ 3 Scan112 | |
| Extract from a letter from C.A. Vandervell & Co. Ltd. announcing new C.A.V. sparking plugs. | 1st Mar 1921 | Box 33 \ 3 Scan113 | |
| Letter from Barracloughs (Engineers) Ltd offering a sample of their improved 'Bradford' Patent spark plug for testing. | 7th Mar 1921 | Box 33 \ 3 Scan114 | |
| Returning correspondence regarding sparking plugs from General Instrument and Engineering Co. Ltd. | 7th Mar 1921 | Box 33 \ 3 Scan115 | |
| Suspected pre-ignition issues with 'Mercury' plugs due to their porcelain design. | 9th Mar 1921 | Box 33 \ 3 Scan116 | |
| Letter from Garage 'Service' Equipment Ltd. offering a set of 'Molla Plugs' for trial. | 9th Mar 1921 | Box 33 \ 3 Scan117 | |
| Price list for spare parts from The British Molla Plug Co. | 9th Mar 1921 | Box 33 \ 3 Scan118 | |
| Exploded view diagram and spare parts price list for the Molla Plug. | 9th Mar 1921 | Box 33 \ 3 Scan119 | |
| Instructional leaflet for the Molla Sparking plug No. 6, detailing its disassembly and regulation. | 9th Mar 1921 | Box 33 \ 3 Scan120 | |
| Advertising leaflet comparing the cost and features of the 'Molla Plug' against a generic alternative. | 9th Mar 1921 | Box 33 \ 3 Scan121 | |
| Advertisement for the 'Over All' or 'O.A.P.' two-piece detachable sparking plug. | 16th Mar 1921 | Box 33 \ 3 Scan122 | |
| Requesting a halt to sending spark plugs for testing, with a specific request for a 'Molla' plug for inspection. | 16th Mar 1921 | Box 33 \ 3 Scan123 | |
| Arranging for a Molia plug to be sent from Garage 'Service' Equipment Ltd. | 18th Mar 1921 | Box 33 \ 3 Scan124 | |
| On testing ignition plugs, noting the failure of a Champion plug and suggesting modifications for Mercury plugs. | 1st Apr 1921 | Box 33 \ 3 Scan125 | |
| Performance issues of Watford magnetos and Lodge spark plugs, referencing a report by PN. | 25th Apr 1921 | Box 33 \ 3 Scan126 | |
| Sales letter from Universal Engineering Co. promoting Igna Sparking Plugs. | 25th Apr 1921 | Box 33 \ 3 Scan127 | |
| Advertisement for IGNA sparking plugs, detailing various models and prices. | 5th May 1921 | Box 33 \ 3 Scan128 | |
| Recommendations on magneto requirements for the 40/50 engine, comparing different magneto and spark plug types. | 5th May 1921 | Box 33 \ 3 Scan129 | |
| Tests carried out on ignition coils with varying secondary turns. | 5th May 1921 | Box 33 \ 3 Scan130 | |
| Magneto ignition requirements and spark gap issues for the 40/50 HP chassis. | 10th May 1921 | Box 33 \ 3 Scan131 | |
| Report discussing engine firing irregularities, focusing on magneto performance, spark plugs, and carburation. | 5th May 1921 | Box 33 \ 3 Scan132 | |
| Magneto ignition requirements, discussing irregular firing and issues with spark plug positioning on 40/50 HP cars. | 10th May 1921 | Box 33 \ 3 Scan133 | |
| Spark plug and magneto performance related to engine slow running, overheating, and oiling issues. | 10th May 1921 | Box 33 \ 3 Scan134 | |
| Advertising leaflet for the Fisher Plug, detailing its features and principle of operation. | 10th May 1921 | Box 33 \ 3 Scan135 | |
| Instructions for the removal and replacement of the Fisher Plug. | 30th May 1921 | Box 33 \ 3 Scan136 | |
| Report condemning the 'Fisher' sparking plug due to design flaws, a doubtful patent, and high cost. | 30th May 1921 | Box 33 \ 3 Scan137 | |
| Instructing to halt the testing of the Fisher Sparking Plug. | 2nd Jun 1921 | Box 33 \ 3 Scan138 | |
| The trial of experimental sparking plugs for chassis No. 79-TW. | 10th Jun 1921 | Box 33 \ 3 Scan139 | |
| Requesting the return of a loaned Fisher Sparking Plug sample. | 13th Jun 1921 | Box 33 \ 3 Scan140 | |
| The despatch of a sample Fisher Sparking Plug to a client. | 15th Jun 1921 | Box 33 \ 3 Scan141 | |
| Advertisement for a dashboard-mounted Manifold Ignition Indicator & Plug Tester. | 6th Jul 1921 | Box 33 \ 3 Scan142 | |
| Extract from a report discussing issues with spark plug positioning for cars destined for America. | 6th Jul 1921 | Box 33 \ 3 Scan143 | |
| Page 2 of a document concerning the position, type, and gap of plugs and compressions. | 1st Jan 1948 | Box 33 \ 3 Scan144 | |
| Position of sparking plugs for cars intended for the American market. | 6th Jul 1921 | Box 33 \ 3 Scan145 | |
| Letter regarding the submission of 13 plugs for testing and a discussion of patent rights. | 12th Jul 1921 | Box 33 \ 3 Scan146 | |
| Requesting tests to be carried out on one dozen AC Plugs No.18 CPT from The A.C. Sparking Plug Co. Ltd. | 16th Jul 1921 | Box 33 \ 3 Scan147 | |
| Letter from A.C. Sparking Plug Co. Ltd. regarding the supply of spark plugs No.18 CPT for testing. | 8th Jul 1921 | Box 33 \ 3 Scan148 | |
| Letter from AC Sparking Plug Co. Ltd. promoting their spark plugs following success at the Le Mans Grand Prix. | 29th Jul 1921 | Box 33 \ 3 Scan149 | |
| French advertisement comparing the cost-effectiveness and features of the 'BOUGIE MOLLA' spark plug against a generic competitor. | 29th Jul 1921 | Box 33 \ 3 Scan150 | |
| Instruction leaflet for the demountable and adjustable Molla No. 6 spark plug. | 4th Aug 1921 | Box 33 \ 3 Scan151 | |
| From CJ to the Experimental Department regarding the testing of an enclosed 'Silca' plug from a customer. | 4th Aug 1921 | Box 33 \ 3 Scan152 | |
| Requesting advice on which make and quantity of sparking plugs to order as stock is at a minimum. | 13th Aug 1921 | Box 33 \ 3 Scan153 | |
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