| Description | Date | Identifier | |
| Letter to S. Smith & Sons, Ltd. requesting a sample electrical rev counter for laboratory tests. | 14th Nov 1935 | Box 165 \ 4 img334 | |
| Letter from S. Smith & Sons (Motor Accessories) Ltd regarding a sample Electrical Rev Indicator for testing purposes. | 15th Nov 1935 | Box 165 \ 4 img335 | |
| Letter from S. Smith & Sons regarding Electric Revolution Indicators and associated generators. | 15th Nov 1935 | Box 165 \ 4 img336 | |
| Letter to S. Smith & Sons regarding generator speed and instrument dial diameter for a sample instrument. | 18th Nov 1935 | Box 165 \ 4 img337 | |
| Letter from S. Smith & Sons concerning an Electrical Revolution Indicator and generator speed specifications. | 20th Nov 1935 | Box 165 \ 4 img338 | |
| Urgent calibration of a 100 m.p.h A.T. speedometer for an experimental chassis. | 22th Nov 1935 | Box 165 \ 4 img339 | |
| Letter from a speedometer company regarding a delay in re-calibrating an instrument due to special requirements. | 2nd Dec 1935 | Box 165 \ 4 img340 | |
| Requesting particulars on a new Jaeger chrono-electric aero engine revolution indicator for aircraft. | 4th Dec 1935 | Box 165 \ 4 img341 | |
| The failure and repair of a speedometer cable for an experimental Phantom III chassis. | 5th Dec 1935 | Box 165 \ 4 img342 | |
| Despatch note sending a speedometer cable to A.T. Speedometer Co. Limited for examination and report. | 7th Dec 1935 | Box 165 \ 4 img343 | |
| The purchase of Jaeger electric rev counters for aircraft. | 9th Dec 1935 | Box 165 \ 4 img344 | |
| The procurement of a Jaeger rev counter for aircraft. | 12th Dec 1935 | Box 165 \ 4 img345 | |
| Letter regarding the procurement of a Jaeger rev counter for aircraft. | 30th Dec 1935 | Box 165 \ 4 img346 | |
| Letter to a speedometer company regarding the failure of a recently recalibrated instrument and the lubrication of its cables. | 18th Dec 1935 | Box 165 \ 4 img347 | |
| Letter discussing a method to reduce noise from drives by lagging cable casings with rubber. | 20th Dec 1935 | Box 165 \ 4 img348 | |
| Letter from the A.T. Speedometer Co., Ltd. regarding a fault with a hand-made speedometer guard. | 20th Dec 1935 | Box 165 \ 4 img349 | |
| Letter from the speedometer supplier regarding cable lubrication and noise reduction. | 20th Dec 1935 | Box 165 \ 4 img350 | |
| Letter to A.T. Speedometer Co. Ltd. regarding speedometer cables and requesting a sample Bentley speedometer for testing. | 23th Dec 1935 | Box 165 \ 4 img351 | |
| Letter from The A.T. Speedometer Co. regarding a special canvas-rubber covered speedometer cable. | 30th Dec 1935 | Box 165 \ 4 img352 | |
| Letter from S. Smith & Sons regarding the progress of an Electric type Speedometer with recorder. | 6th Jan 1936 | Box 165 \ 4 img353 | |
| Internal memorandum regarding the failed testing of a Smith electrical rev-counter and its subsequent return. | 10th Jan 1936 | Box 165 \ 4 img354 | |
| Letter from S. Smith & Sons regarding the damping of an A.T. Speedometer needle. | 15th Jan 1936 | Box 165 \ 4 img355 | |
| Letter from S. Smith & Sons arranging a visit to discuss electric speedometers. | 27th Jan 1935 | Box 165 \ 4 img356 | |
| Letter from S. Smith & Sons rescheduling a visit to discuss electric speedometers. | 28th Jan 1936 | Box 165 \ 4 img357 | |
| Letter to Messrs. S. Smith & Sons, Ltd. regarding the postponement of a visit by Mr. V. Russell. | 28th Jan 1936 | Box 165 \ 4 img358 | |
| Letter from S. Smith & Sons arranging a visit to discuss Electric Speedometers. | 29th Jan 1936 | Box 165 \ 4 img359 | |
| Order be placed with A.T. Speedometer Co. Ltd. for a speedometer and specially insulated cables. | 17th Feb 1936 | Box 165 \ 4 img360 | |
| Testing an A.T. speedometer with increased damping and concluding it offers no significant improvement. | 21th Feb 1936 | Box 165 \ 4 img361 | |
| Proposing a new, adjusted rev-counter for car 3-B-IV due to incorrect readings after an alteration to the dynamo drive. | 29th Feb 1936 | Box 165 \ 4 img362 | |
| Internal request to send a covering order for a speedometer to A.T. Speedometer Co. Ltd. | 7th Apr 1936 | Box 165 \ 4 img363 | |
| Confirmation of an alternative tachometer drive for chassis S-B-IV with the wider frame and its running speed. | 24th Apr 1936 | Box 165 \ 4 img364 | |
| Investigation into the Phantom III speedometer drive running dry and the proposed modifications to resolve the issue. | 15th May 1936 | Box 165 \ 4 img365 | |
| Letter to the A.T. Speedmoeter Co. arranging a meeting to discuss noisy drives and comparing them to American units. | 15th Jun 1936 | Box 165 \ 4 img366 | |
| Letter from A.T. Speedometer Co. Ltd. regarding a visit by Mr. Arrowsmith. | 17th Jun 1936 | Box 165 \ 4 img367 | |
| Letter to A.T. Speedometer Co. Ltd. agreeing to the creation of a sample speedometer drive for testing, based on a part from an American Packard car. | 3rd Jul 1936 | Box 165 \ 4 img368 | |
| Letter from Foster Instrument Co Ltd advising they no longer make electrical revolution indicators and suggesting other suppliers. | 12th Aug 1936 | Box 165 \ 4 img369 | |
| Letter to Salford Electrical Instruments, Ltd. requesting particulars of electrical revolution indicators. | 13th Aug 1936 | Box 165 \ 4 img370 | |
| Letter acknowledging an enquiry for Electrical Revolution Indicators and forwarding it to the Birmingham branch. | 20th Aug 1936 | Box 165 \ 4 img371 | |
| Request to order and supply a replacement synchronous speed motor for the rev counter rig. | 16th Oct 1936 | Box 165 \ 4 img372 | |
| Request to place an order with Messrs. A.T. Speedometer Co. Ltd. for a Bentley rev-counter. | 16th Oct 1936 | Box 165 \ 4 img373 | |
| Request to order an A.T. Speedometer for Experimental Car 5-B-IV, specifying the back-axle ratio and calculated revolutions per mile. | 19th Oct 1936 | Box 165 \ 4 img374 | |
| Faulty speedometer from a Phantom III (36-EX) being returned for overhaul and repair. | 30th Oct 1936 | Box 165 \ 4 img375 | |
| Instruction to despatch a speedometer for overhaul as per order. | 3rd Nov 1936 | Box 165 \ 4 img376 | |
| Letter from Dobbie McInnes & Clyde Ltd to Bentleys Motors promoting the 'Farnboro' Electric Indicator for engine testing. | 3rd Nov 1936 | Box 165 \ 4 img377 | |
| Promotional leaflet for the 'Dobie-McInnes' 'Farnboro' Electric Indicator, detailing its use with time-base diagrams for high-speed engines. | 14th Dec 1934 | Box 165 \ 4 img378 | |
| Analysis of indicator diagrams showing the effects of fuel injection timing and engine speed on combustion pressures. | 1st Oct 1936 | Box 165 \ 4 img379 | |
| Investigation report into a Magneto unit that was cutting out during endurance tests. | 1st Oct 1936 | Box 165 \ 4 img380 | |
| Letter to the Air Ministry requesting a recommendation for a reliable method of checking revolution indicators. | 4th Nov 1936 | Box 165 \ 4 img381 | |
| Failed Hasler rev-counter on a test rig, requesting it be returned to the makers for repair. | 6th Nov 1936 | Box 165 \ 4 img382 | |
| Specification document for the speedometer drive on the Wraith II gearbox. | 23th Nov 1936 | Box 165 \ 4 img383 | |
| Faulty speedometer from Phantom car 32-EX reading 3 MPH fast. | 3rd Dec 1936 | Box 165 \ 4 img384 | |
| Experimental ignition parts dismantled from chassis 93-NK. | 23th Feb 1925 | Box 165 \ 5 img001 | |
| Requesting the deletion of the flexible earthing connection for the condenser from production instructions following a successful test. | 22th Sep 1926 | Box 165 \ 5 img002 | |
| Production test procedure for a paper dielectric condenser for battery ignition. | 15th Oct 1926 | Box 165 \ 5 img003 | |
| Testing procedures and specifications for condensers, detailing capacity and static charge retention checks at various temperatures. | 11th Jan 1928 | Box 165 \ 5 img004 | |
| Proposal to test paraffin wax-impregnated paper for use in ignition coils and condensers. | 11th Jan 1928 | Box 165 \ 5 img005 | |
| Proposal to test three coils and three condensers wound with wax paper as insulation. | 25th Jan 1928 | Box 165 \ 5 img006 | |
| To EFC regarding the dispatch of two P.W.P. condensers and the modification of coils to meet capacity limits. | 24th Feb 1928 | Box 165 \ 5 img007 | |
| Testing of new insulating papers from a British source for use in ignition coils and condensers. | 9th May 1928 | Box 165 \ 5 img008 | |
| Temperature leakage tests conducted on various insulating papers. | 8th May 1928 | Box 165 \ 5 img009 | |
| Properties of a new material and recommending tests before its adoption for coils and condensers. | 7th Jun 1928 | Box 165 \ 5 img010 | |
| Comparative tests of varnished and waxed papers for ignition coils and condensers. | 7th Jun 1928 | Box 165 \ 5 img011 | |
| Tests on various insulating papers to compare their performance under heat and electrical stress. | 31th May 1928 | Box 165 \ 5 img012 | |
| Test results on the conductance and dielectric strength of various papers after heating cycles. | 31th May 1928 | Box 165 \ 5 img013 | |
| Comparison of varnished and waxed papers for use in condensers and ignition coils, considering dielectric strength and temperature effects. | 8th Aug 1928 | Box 165 \ 5 img014 | |
| Instructing the construction of ignition coils and condensers, with a later handwritten amendment cancelling the condensers. | 8th Aug 1928 | Box 165 \ 5 img015 | |
| The testing and modification of paraffin waxed paper condensers for specific chassis. | 8th Jun 1929 | Box 165 \ 5 img016 | |
| Request for the production of two more paraffin waxed paper condensers for experimental chassis and bench testing. | 8th Jun 1929 | Box 165 \ 5 img017 | |
| The performance of paraffin waxed paper condensers for battery ignition systems. | 12th May 1930 | Box 165 \ 5 img018 | |
| Request to carry out condenser tests on a 20/25 HP chassis to observe effects on low-speed battery ignition. | 23th May 1930 | Box 165 \ 5 img019 | |
| Request for experimental tests on three condensers with modified capacities to improve contact point life. | 8th Sep 1930 | Box 165 \ 5 img020 | |
| The measured capacities of seven B.I. condensers borrowed from production. | 1st Sep 1930 | Box 165 \ 5 img021 | |
| Issues with production battery ignition condensers exceeding their capacity limits and proposing a new type of paraffin waxed paper condenser. | 24th Sep 1930 | Box 165 \ 5 img022 | |
| Requesting a second set of experimental condensers and detailing findings on ignition performance. | 24th Sep 1930 | Box 165 \ 5 img023 | |
| Letter to Mr. Minchin regarding ignition misfiring, 20 HP ignition duplication, and condenser capacity for tungsten points. | 24th Sep 1930 | Box 165 \ 5 img024 | |
| Letter regarding the testing of lower capacity condensers to address misfiring. | 24th Sep 1930 | Box 165 \ 5 img025 | |
| Request to obtain 2 rolls of 2-ply waxed paper for experimental condensers. | 26th Sep 1930 | Box 165 \ 5 img026 | |
| Clarifying condenser specifications, instructing the Works to reduce the number of turns from 28 to 25 and prioritize the capacity limit. | 29th Sep 1930 | Box 165 \ 5 img027 | |
| Fitting of a special waxed paper ignition condenser to chassis 18-GIV for standardization testing. | 10th Oct 1930 | Box 165 \ 5 img028 | |
| Performance of tungsten contact points in battery ignition systems and the required condenser capacity. | 4th Oct 1930 | Box 165 \ 5 img029 | |
| Investigation into condenser capacity, materials, and their effects on ignition distributor contact points. | 14th Oct 1930 | Box 165 \ 5 img030 | |
| Distributor bench tests investigating condenser capacity and its effect on screw point oxidation. | 4th Oct 1930 | Box 165 \ 5 img031 | |
| Condenser capacity testing on different chassis to address point oxidation and misfiring. | 4th Oct 1930 | Box 165 \ 5 img032 | |
| Letter to Mr. Minchin discussing 20 HP ignition, misfiring on the 20/25 model, and condenser capacity for tungsten points. | 24th Sep 1930 | Box 165 \ 5 img033 | |
| Letter to Messrs. Peto & Radford regarding the testing of lower capacity condensers to cure misfiring. | 24th Sep 1930 | Box 165 \ 5 img034 | |
| Request to supply two paraffin wax condensers of reduced capacity with specific materials. | 30th Oct 1930 | Box 165 \ 5 img035 | |
| 10,000-mile test of paraffin waxed paper condensers, analysing capacity changes and contact point wear. | 26th Jan 1931 | Box 165 \ 5 img036 | |
| Request to fit a lower capacity paraffin wax paper ignition condenser and new tungsten contacts to chassis 20-EX. | 27th Jan 1931 | Box 165 \ 5 img037 | |
| Condensers for the 40-50 HP and 20 HP chassis, and a request for two modified condensers for a test car. | 22th Jun 1931 | Box 165 \ 5 img038 | |
| Standardisation of a paraffin waxed paper condenser, changing from .30 mf to .23 mf capacity with a reinforced case bottom. | 15th Oct 1931 | Box 165 \ 5 img039 | |
| Standardisation form for a reinforced case bottom part to improve surface condition. | 20th Jan 1932 | Box 165 \ 5 img040 | |
| Extract from a report on distributor contact points and condenser performance on an 18-GIV model after a 10,000-mile test. | 30th Jan 1931 | Box 165 \ 5 img041 | |
| The advantages and performance of lower capacity paraffin waxed paper condensers for ignition systems. | 9th Feb 1931 | Box 165 \ 5 img042 | |
| Battery ignition condenser's capacity and material composition. | 2nd Feb 1931 | Box 165 \ 5 img043 | |
| The results of a 10,000-mile test of a smaller capacity condenser for ignition distributors. | 29th Apr 1931 | Box 165 \ 5 img044 | |
| Returned Condenser from a 20/25 HP chassis, which was tested and found not to be faulty. | 14th May 1931 | Box 165 \ 5 img045 | |
| Explaining the failure to record mileage during a condenser change on chassis GLR-8. | 1st May 1931 | Box 165 \ 5 img046 | |
| Listing two suppliers for condenser tinfoil. | 9th Feb 1932 | Box 165 \ 5 img047 | |
| Requesting the production of three condensers for 'Japan III', listing the necessary parts and noting the need to order waxed paper. | 3rd Mar 1932 | Box 165 \ 5 img048 | |
| The construction of a new cylindrical condenser for the J.3. ignition system. | 14th Mar 1932 | Box 165 \ 5 img049 | |
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