| Description | Date | Identifier | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. discussing the progress on aero and Bentley car sparking plugs. | 8th Jul 1936 | Box 163 \ 5 img044 | |
| Inquiry to the AC-Sphinx Sparking Plug company regarding engine misfiring on a Bentley using leaded fuel, asking if ceramic plugs are better than mica plugs. | 9th Jul 1936 | Box 163 \ 5 img045 | |
| Letter from the AC-Sphinx Sparking Plug Co. Ltd. concerning misfiring of motor car plugs and the benefits of their ceramic plugs. | 10th Jul 1936 | Box 163 \ 5 img046 | |
| Letter from AC-Sphinx Sparking Plug Co. regarding the prioritisation of Aero plugs over Bentley plugs. | 10th Jul 1936 | Box 163 \ 5 img047 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. regarding the gap setting dimension for a sample set of 24 aero sparking plugs. | 13th Aug 1936 | Box 163 \ 5 img048 | |
| Letter to a spark plug company specifying the required plug gap setting. | 15th Aug 1936 | Box 163 \ 5 img049 | |
| Letter from The AC-Sphinx Sparking Plug Co. Ltd. regarding gap limits for twenty-four sample screened plugs. | 17th Aug 1936 | Box 163 \ 5 img050 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. concerning the delivery of sample aircraft plugs for testing. | 28th Aug 1936 | Box 163 \ 5 img051 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. concerning sample experimental sparking plugs for Bentley. | 1st Sep 1936 | Box 163 \ 5 img052 | |
| Letter to A.C. Sparking Plug & Co. Ltd regarding the failure of experimental aero plugs type X410 and X412 on a Merlin engine. | 2nd Sep 1936 | Box 163 \ 5 img053 | |
| Request to arrange the return of faulty A.C. plugs to the manufacturer due to welding defects. | 2nd Sep 1936 | Box 163 \ 5 img054 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. discussing welding problems with spark plug screen extensions. | 3rd Sep 1936 | Box 163 \ 5 img055 | |
| Letter from AC-Sphinx Sparking Plug Co. regarding plug performance with screens and a request for engine drawings. | 4th Sep 1936 | Box 163 \ 5 img056 | |
| Letter to AC-Sphinx Sparking Plug Co. Ltd. declining to test non-standard plugs and arranging a meeting. | 4th Sep 1936 | Box 163 \ 5 img057 | |
| Letter from The AC-Sphinx Sparking Plug Co. Ltd. arranging a meeting with Mr. H. E. West. | 6th Sep 1936 | Box 163 \ 5 img058 | |
| Urgent request for a dozen Bentley sparking plugs with Sinterkorund insulators. | 16th Sep 1936 | Box 163 \ 5 img059 | |
| Letter from a supplier about the dispatch of experimental sparking plugs for a Bentley, requesting a performance report on previous samples. | 17th Sep 1936 | Box 163 \ 5 img060 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. regarding sending experimental Sparking Plugs type X399 for a Bentley job. | 21th Sep 1936 | Box 163 \ 5 img061 | |
| Letter to AC-Sphinx Sparking Plug Co. regarding modification of special aero plugs and pre-ignition issues with X.399 Bentley plugs. | 23th Sep 1936 | Box 163 \ 5 img062 | |
| Request for a covering order for AC-Sphinx spark plugs supplied for testing on a Bentley chassis. | 23th Sep 1936 | Box 163 \ 5 img063 | |
| Letter to AC-Sphinx Sparking Plug Co. regarding misfiring and pre-ignition issues with X399 plugs on a Bentley chassis. | 24th Sep 1936 | Box 163 \ 5 img064 | |
| Letter concerning a revised method for securing screened extensions on aero plugs and addressing suspected pre-ignition in Bentley plugs. | 24th Sep 1936 | Box 163 \ 5 img065 | |
| Letter from the AC-Sphinx Sparking Plug company regarding a complaint of misfiring plugs on a Bentley chassis. | 25th Sep 1936 | Box 163 \ 5 img066 | |
| Decision not to send AC plugs as Professor Dodds' car is now at the Works. | 30th Sep 1936 | Box 163 \ 5 img067 | |
| Letter from AC-Sphinx Sparking Plug Co. regarding an order and testing of experimental plugs for Bentley and aero engines. | 1st Oct 1936 | Box 163 \ 5 img068 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. regarding a fractured plug and testing of other X399 plugs. | 2nd Oct 1936 | Box 163 \ 5 img069 | |
| Letter to a spark plug company regarding the testing and performance of plugs for a Bentley. | 2nd Oct 1936 | Box 163 \ 5 img070 | |
| Thank you letter to AC-Sphinx Sparking Plugs Ltd. for the offer of supplying X399 plugs free of charge. | 5th Oct 1936 | Box 163 \ 5 img071 | |
| Letter to AC-Sphinx Sparking Plug Co. Ltd. regarding a broken special aero sparking plug. | 15th Oct 1936 | Box 163 \ 5 img072 | |
| Arranging the return of a special AC aero plug to AC-Sphinx Sparking Plugs Ltd. for inspection and repair. | 16th Oct 1936 | Box 163 \ 5 img073 | |
| Letter regarding a broken special aero plug, its replacement, and arrangements for future correspondence. | 20th Oct 1936 | Box 163 \ 5 img074 | |
| Free of Charge invoice for experimental spark plugs from the AC-Sphinx Sparking Plug Co. Ltd. | 21th Oct 1936 | Box 163 \ 5 img075 | |
| Confirming receipt of spark plugs from AC-Sphinx Sparking Plug Co. Ltd. and requesting they are booked in. | 22th Oct 1936 | Box 163 \ 5 img076 | |
| Letter to AC-Sphinx Sparking Plugs requesting six 10mm plugs for an experimental trial on Bentley cars. | 22th Oct 1936 | Box 163 \ 5 img077 | |
| Letter from AC-SPHINX confirming the dispatch of six 10 mm sample spark plugs (No.303) for experimental trials on Bentley cars. | 26th Oct 1936 | Box 163 \ 5 img078 | |
| Test report on A.C. special plugs with R type integral fittings on a Kestrel single cylinder engine. | 30th Oct 1936 | Box 163 \ 5 img079 | |
| Request to send a covering order to Messrs. A.C. Sparking Plugs Ltd. for 10mm plugs. | 30th Oct 1936 | Box 163 \ 5 img080 | |
| Letter to a supplier regarding modifications and test results for sparking plugs. | 9th Nov 1936 | Box 163 \ 5 img081 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. regarding the supply of spark plugs for testing. | 13th Nov 1936 | Box 163 \ 5 img082 | |
| Order be sent to The A.C. Sphinx Sparking Plug Co. Ltd. | 16th Nov 1936 | Box 163 \ 5 img083 | |
| From Rm/Wst to Roy requesting a covering order for one dozen X.K.14 spark plugs. | 3rd Dec 1936 | Box 163 \ 5 img084 | |
| Letter to A.C.-Sphinx Sparking Plug Co. Ltd. regarding minimum sparking plug dimensions. | 4th Dec 1936 | Box 163 \ 5 img085 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. to Mr. H.E. West arranging a meeting. | 2nd Dec 1936 | Box 163 \ 5 img086 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. regarding a delay in supplying plugs due to the need to manufacture new insulators. | 7th Dec 1936 | Box 163 \ 5 img087 | |
| Letter from AC-Sphinx Sparking Plug Co. regarding the supply of experimental aero plugs. | 17th Feb 1937 | Box 163 \ 5 img088 | |
| Invoice from The AC-Sphinx Sparking Plug Co. Ltd. for experimental spark plugs. | 18th Feb 1937 | Box 163 \ 5 img089 | |
| Letter regarding the receipt and testing of Sinterkorund Sparking Plugs. | 1st May 1937 | Box 163 \ 5 img090 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. requesting a small quantity of Invar steel to continue experiments after their supply was lost in transit. | 13th May 1937 | Box 163 \ 5 img091 | |
| Letter to N.F. Stockbridge of A.C. Sphinx Sparking Plug Co. Ltd. regarding material availability. | 14th May 1937 | Box 163 \ 5 img092 | |
| Letter from AC-Sphinx Sparking Plug Co. regarding the development and sampling of aircraft plugs. | 12th Jun 1937 | Box 163 \ 5 img093 | |
| The testing and failure of two types of AC sparking plugs. | 18th Nov 1937 | Box 163 \ 5 img094 | |
| Follow-up letter from AC-Sphinx Sparking Plug Co. regarding information for Sparking Plug Caps and Bentley models. | 7th Dec 1937 | Box 163 \ 5 img095 | |
| Letter to AC-Sphinx Sparking Plug Co. Ltd. declining to recommend their spark plugs. | 22th Dec 1937 | Box 163 \ 5 img096 | |
| Request to obtain two dozen type 46 sparking plugs for a 'Buick' from A.C. Co. Ltd. | 15th Jul 1939 | Box 163 \ 5 img097 | |
| Order for two dozen K.C.7. Sparking Plugs for Vauxhall. | 9th Jan 1940 | Box 163 \ 5 img098 | |
| Order for 24 K9V sparking plugs from A.C. Sparking Plugs Ltd. | 25th Jan 1940 | Box 163 \ 5 img099 | |
| Letter to a spark plug company about engine misfiring issues and a request for hotter running plugs due to poor petrol quality. | 24th Feb 1940 | Box 163 \ 5 img100 | |
| Letter from AC-Sphinx Sparking Plug Co. enquiring about the makes and types of plugs being fitted to various car models. | 28th Feb 1940 | Box 163 \ 5 img101 | |
| Requesting the acquisition of 12 KD.7.A. type plugs from A.C. Sphinx Sparking Plug Co. | 6th Mar 1940 | Box 163 \ 5 img102 | |
| Letter to A.C. Sphinx Plug Co. Ltd. regarding the purchase and testing of KD.7.A. type spark plugs for a 1939 class car. | 6th Mar 1940 | Box 163 \ 5 img103 | |
| Letter requesting full particulars of mechanical petrol pumps for 30 HP and 40-50 HP engines. | 30th Aug 1940 | Box 163 \ 5 img104 | |
| Specifications for a 20/25 HP Tank Engine Dynamo. | 11th Jan 1934 | Box 163 \ 6 img001 | |
| Car dynamo output, two-point charging switches, and trickle charging devices. | 5th Dec 1929 | Box 163 \ 6 img002 | |
| Potential improvements to battery charging systems, referencing a Lucas switch and a vibrator control. | 23th Dec 1929 | Box 163 \ 6 img003 | |
| Dynamo output, increased electrical load from lamps, and battery charging solutions. | 23th Dec 1929 | Box 163 \ 6 img004 | |
| Technical memorandum discussing battery charging issues and potential modifications to the Lucas system. | 24th Dec 1929 | Box 163 \ 6 img005 | |
| Suggestion to modify the dynamo conductors and battery charging system to accommodate different seasonal and driving conditions. | 24th Dec 1929 | Box 163 \ 6 img006 | |
| Reduced charge switching and its interconnection with the headlamp switch. | 8th Jan 1930 | Box 163 \ 6 img007 | |
| Technical memorandum discussing a new design for a switchbox, armature contact, and lamp switching. | 8th Jan 1936 | Box 163 \ 6 img008 | |
| The issues with the auxiliary magneto switch, proposing its removal from the ignition system. | 8th Jan 1930 | Box 163 \ 6 img009 | |
| Proposals for modifying the switchbox for increased charge switching. | 25th Jan 1930 | Box 163 \ 6 img010 | |
| Proposed arrangements and issues with reduced charge switching circuitry. | 30th Jan 1930 | Box 163 \ 6 img011 | |
| Hand-drawn sketch of four circuit diagrams, labeled FIG 1 to FIG 4. | 30th Jan 1930 | Box 163 \ 6 img012 | |
| Proposed wiring modifications for the distribution and switchbox connections, continued on page 2. | 30th Jan 1930 | Box 163 \ 6 img013 | |
| Note discussing the convention for indicating windings and a scheme for reduced charge switching with higher output generators. | 30th Jan 1930 | Box 163 \ 6 img014 | |
| Test report on the dissipation of field resistance suitable for reducing dynamo output. | 15th Feb 1930 | Box 163 \ 6 img015 | |
| Utilising ballast resistance and a lamp to indicate a reduced charge state. | 15th Feb 1930 | Box 163 \ 6 img016 | |
| Alternative proposal for reduced charge switching on the right-hand switch. | 8th Feb 1930 | Box 163 \ 6 img017 | |
| The required resistance for reduced charge switching, specifying the length and gauge of Eureka wire needed. | 7th Mar 1930 | Box 163 \ 6 img018 | |
| The parts and modifications required for a 20-HP chassis dynamo with half-charge control. | 8th Mar 1930 | Box 163 \ 6 img019 | |
| Parts required to modify a switchbox for a 40-50 HP Chassis No. 23-EX. | 17th Mar 1930 | Box 163 \ 6 img020 | |
| Distribution Board and Cutout for a 40-50 HP Chassis No. 23-EX, detailing required modifications and parts. | 17th Mar 1930 | Box 163 \ 6 img021 | |
| Parts list and request to produce a Dynamo Resistance Unit for 'D' Scheme 315, Chassis 23-EX. | 18th Mar 1930 | Box 163 \ 6 img022 | |
| Test report on the suitability of a field resistance for a 40/50 high output dynamo. | 24th Mar 1930 | Box 163 \ 6 img023 | |
| Requesting instructions for a half charge switching scheme for the 20/25 chassis. | 2nd Apr 1930 | Box 163 \ 6 img024 | |
| Specification for Half Charge Switching on a 20/25 HP Chassis. | 3rd Apr 1940 | Box 163 \ 6 img025 | |
| Dynamo modifications for 20 HP Chassis Number 18-G-4, including new bearing bracket parts. | 9th Apr 1930 | Box 163 \ 6 img026 | |
| The parts required for a modified switchbox for a 20/25 HP, chassis 18-GIV, to enable Half Charge Switching. | 4th Apr 1930 | Box 163 \ 6 img027 | |
| Trial resistances for half charge, showing an original proposal and subsequent standardized values. | 14th Apr 1930 | Box 163 \ 6 img028 | |
| Reduced charge data for resistance inserted in the armature circuit. | 16th Apr 1930 | Box 163 \ 6 img029 | |
| Decision memo comparing two electrical schemes for reduced charge switching on a left-hand drive chassis. | 16th Apr 1930 | Box 163 \ 6 img030 | |
| Analysis of an alternative electrical wiring scheme (Scheme 2) and its effects on the dynamo and charge circuits. | 16th Apr 1930 | Box 163 \ 6 img031 | |
| Wiring instructions and diagrams for a switchbox and distribution box. | 7th Apr 1930 | Box 163 \ 6 img032 | |
| Requesting the creation of trial resistances using Eureka wire for half charge. | 7th Apr 1930 | Box 163 \ 6 img033 | |
| Request to produce a modified Distribution Board and Cutout for a 20 HP Chassis 18-GIV, listing the required additional parts. | 16th Apr 1930 | Box 163 \ 6 img034 | |
| Sending two special resistances for trial on chassis 24-EX to Mr. Elliott in France. | 26th Apr 1930 | Box 163 \ 6 img035 | |
| Works order for the dispatch of special resistances for trial with the half charge scheme to Mr. F.H. Royce in France. | 28th Apr 1930 | Box 163 \ 6 img036 | |
| Issuing instructions for a reduced charge switching system for the 20 HP, 10,000 mile chassis. | 28th Apr 1930 | Box 163 \ 6 img037 | |
| Trials on different resistance units to achieve a reduced charge field resistance. | 28th Apr 1930 | Box 163 \ 6 img038 | |
| Dynamo output improvements for the Phantom II and 25 HP models. | 6th May 1930 | Box 163 \ 6 img039 | |
| | | | |
