| Description | Date | Identifier | |
| Testing of a Jaeger speedometer and the decision not to standardise it. | 10th Jan 1929 | Box 165 \ 4 img034 | |
| Comparing the A.T. and Jaeger speedometers, recommending the continued use of the A.T. model. | 11th Feb 1929 | Box 165 \ 4 img035 | |
| Page 2 of a typed document discussing the need to educate A.T. people to meet requirements. | 11th Feb 1929 | Box 165 \ 4 img036 | |
| Letter from The De Lavaud Holdings Corporation to L. Hives regarding a British Patent for an engine indicator. | 6th May 1929 | Box 165 \ 4 img037 | |
| The second page of a typed letter, concluding with a signature. | 28th Mar 1928 | Box 165 \ 4 img038 | |
| Copy of a patent specification for improvements in indicating mechanisms using a wheatstone bridge. | 28th Mar 1928 | Box 165 \ 4 img039 | |
| Description of an apparatus designed to measure pressure variations within the combustion chamber of an internal combustion engine. | 28th Mar 1928 | Box 165 \ 4 img040 | |
| Description of a mechanism for indicating pressure variations, detailing the construction of the diaphragm, cooling system, and electrical connections. | 28th Mar 1928 | Box 165 \ 4 img041 | |
| List of claims for an invention related to indicating and pressure indicating mechanisms. | 28th Mar 1928 | Box 165 \ 4 img042 | |
| Specification for an indicating mechanism using a wheatstone bridge. | 28th Mar 1928 | Box 165 \ 4 img043 | |
| Detailed schematic of an oscillograph element. | 28th Mar 1928 | Box 165 \ 4 img044 | |
| Patent drawing showing cross-sections of a mechanical valve or injector assembly. | 28th Mar 1928 | Box 165 \ 4 img045 | |
| Specification for an improved combination spark plug and pressure indicator for an internal combustion engine. | 28th Mar 1928 | Box 165 \ 4 img046 | |
| Description of a thrust element indicator using a diaphragm, carbon pile rheostats, and a Wheatstone bridge circuit. | 28th Mar 1928 | Box 165 \ 4 img047 | |
| Description of an indicating mechanism for recording pressure variations in a combustion chamber using an oscillograph. | 28th Mar 1928 | Box 165 \ 4 img048 | |
| List of claims for an improvement or modification to a patent for a combined indicator and spark plug. | 28th Mar 1928 | Box 165 \ 4 img049 | |
| Patent-style drawing of an oscillograph element and its associated mechanical assembly. | 28th Mar 1928 | Box 165 \ 4 img050 | |
| Patent-style design drawing of a mechanical adjustment mechanism. | 9th May 1929 | Box 165 \ 4 img051 | |
| Letter to Commander Briggs regarding Mr. Constantine's indicator invention. | 9th May 1929 | Box 165 \ 4 img052 | |
| Requesting instructions to despatch Hasler speed indicator No. 2687 for repair. | 16th Sep 1929 | Box 165 \ 4 img053 | |
| Proposal for a new electrical speedometer design using an alternator and a moving coil instrument with a metal rectifier. | 25th Apr 1930 | Box 165 \ 4 img054 | |
| New reliable scheme for a magneto D.C. generator, addressing previous unreliability. | 25th Apr 1930 | Box 165 \ 4 img055 | |
| Concept of an alternator-driven electrical speedometer and proposing a test method. | 28th Apr 1930 | Box 165 \ 4 img056 | |
| Small alternator for preliminary tests on an electrical speedometer. | 29th Apr 1930 | Box 165 \ 4 img057 | |
| Preliminary test for an electrical speedometer using a small alternator and a bridge rectifier instrument. | 29th Apr 1930 | Box 165 \ 4 img058 | |
| Faulty small alternator generator hand-lamp. | 12th May 1930 | Box 165 \ 4 img059 | |
| Confirming receipt of a hand drive alternator for testing as a speedometer. | 3rd May 1930 | Box 165 \ 4 img060 | |
| Development and testing of an electrical speedometer using an alternator and milliammeter. | 20th May 1930 | Box 165 \ 4 img061 | |
| The application of synchronous motors for mileage and time measurement. | 20th May 1930 | Box 165 \ 4 img062 | |
| Description of a speedometer and mileometer arrangement using an alternator, rectifier, and synchronous motor. | 20th May 1930 | Box 165 \ 4 img063 | |
| Letter to Messrs. Everett Edgecumbe Ltd. inquiring about the capabilities of a Warren synchronous motor on a variable frequency supply. | 20th May 1930 | Box 165 \ 4 img064 | |
| Letter from Everett, Edgcumbe & Co Ltd discussing the performance of Warren Synchronous Motors under variable frequency and voltage. | 23th May 1930 | Box 165 \ 4 img065 | |
| Letter from Everett, Edgcumbe & Co. Ltd. concerning the qualities of Warren synchronous motors. | 23th May 1930 | Box 165 \ 4 img066 | |
| Sending a revolution counter to Messrs. Jaegar (London) Ltd. for repair. | 23th May 1930 | Box 165 \ 4 img067 | |
| Letter to Everett Edgcumbe & Co. Ltd clarifying an enquiry about the operational range of a Warren Motor. | 26th May 1930 | Box 165 \ 4 img068 | |
| Letter clarifying the operational parameters for a Warren Motor regarding voltage and frequency variations. | 29th May 1930 | Box 165 \ 4 img069 | |
| Report on a Blackburn 'Sydney' Machine fitted with F.XII.MS. engines. | 29th May 1930 | Box 165 \ 4 img070 | |
| Letter detailing preliminary notes and concerns regarding the installation of a 'Sydney Machine' engine. | 28th May 1930 | Box 165 \ 4 img071 | |
| On-site machine installation, detailing progress and issues encountered including a machine surrounded by scaffolding. | 30th May 1930 | Box 165 \ 4 img072 | |
| Letter to The Record Electrical Co. Ltd. regarding a query about their electrical engine revolution indicators. | 30th May 1930 | Box 165 \ 4 img073 | |
| The experience and testing of new electrical engine revolution indicators for an aero engine. | 30th May 1930 | Box 165 \ 4 img074 | |
| Letter from The Record Electrical Company Limited regarding an Electrical Tachometer and other instruments. | 31th May 1930 | Box 165 \ 4 img075 | |
| Continuation sheet from The Record Electrical Company Limited regarding a visit from their representative. | 3rd Jun 1930 | Box 165 \ 4 img076 | |
| Electrical revolution indicator made by The Record Electrical Co. Ltd. | 3rd Jun 1930 | Box 165 \ 4 img077 | |
| Arranging for the loan of an electric revolution speed indicator. | 9th Jul 1930 | Box 165 \ 4 img078 | |
| The specifications of an aero engine speedometer from The Record Electrical Co. | 12th Jun 1930 | Box 165 \ 4 img079 | |
| Request to order a sample dynamo for an electrical revolution indicator for Aero Engines. | 23th Jul 1930 | Box 165 \ 4 img080 | |
| Letter from the Royal Aircraft Establishment regarding the dispatch of an Engine Speed Indicator. | 23th Aug 1930 | Box 165 \ 4 img081 | |
| Calibration data for a Record Mark I.A. Revolution Indicator, showing instrument errors at various RPMs. | 20th Aug 1930 | Box 165 \ 4 img082 | |
| The alteration of Phantom II radiator thermometers to address over-heating problems. | 26th Aug 1930 | Box 165 \ 4 img083 | |
| Information regarding overheating issues and the cooling system design for the Phantom II model. | 1st Sep 1930 | Box 165 \ 4 img084 | |
| Instructions regarding the radiator shutter warning lamp and bonnet ventilation for hot weather. | 2nd Sep 1930 | Box 165 \ 4 img085 | |
| Guidance on interpreting the red warning lamp and using the cut-out on Continental roads. | 2nd Sep 1930 | Box 165 \ 4 img086 | |
| Standardisation of the warning light operation on the thermometer to activate at 97.5°C. | 1st Aug 1930 | Box 165 \ 4 img087 | |
| Three proposed modifications to address overheating issues in the Phantom II model. | 4th Sep 1930 | Box 165 \ 4 img088 | |
| Overheating tests on a Phantom II, focusing on modifying the undershields. | 8th Sep 1930 | Box 165 \ 4 img089 | |
| Request to return a faulty Hasler speed indicator to the makers for readjustment. | 23th Sep 1930 | Box 165 \ 4 img090 | |
| Inspection and testing of a loaned Electric Revolution Indicator. | 25th Sep 1930 | Box 165 \ 4 img091 | |
| Air Ministry correspondence regarding the loan of an Electric Revolution Indicator for engine testing. | 20th Sep 1930 | Box 165 \ 4 img092 | |
| The fitting and testing of an aero engine electrical speedometer, noting a missing part. | 1st Oct 1930 | Box 165 \ 4 img093 | |
| Instruction leaflet for the installation of flexible shaft drives for engine speed indicators. | 9th Jul 1929 | Box 165 \ 4 img094 | |
| Instructions for adjusting a shaft and casing, including a method for shortening the shaft. | 14th Mar 1929 | Box 165 \ 4 img095 | |
| Instruction leaflet for the installation of an electric engine speed indicator, Mark IA. | 14th Mar 1929 | Box 165 \ 4 img096 | |
| Maintenance instructions for the generator and flexible drive lubrication. | 24th Aug 1930 | Box 165 \ 4 img097 | |
| Letter from a machinery supplier about electrically operated long-distance tachometers for aeroplanes. | 24th Aug 1930 | Box 165 \ 4 img098 | |
| Request to fit an Electrical Revolution Counter on No.3 Test Bed for testing. | 28th Oct 1930 | Box 165 \ 4 img099 | |
| Observation of an Aero Engine Electrical Speedometer fitted to an F.10 engine. | 25th Nov 1930 | Box 165 \ 4 img100 | |
| The testing of an aero engine electrical speedometer on a test bed. | 27th Nov 1930 | Box 165 \ 4 img101 | |
| Letter to North & Sons, Ltd. regarding the testing of a 100 m.p.h. Watford Magnetic type Speedometer and required modifications. | 19th Jun 1931 | Box 165 \ 4 img102 | |
| Test report on a Watford 100 m.p.h. magnetic type speedometer. | 9th Jun 1931 | Box 165 \ 4 img103 | |
| Graph showing the drop in M.P.H. reading with a rise in temperature for two types of magnetic speedometers. | 3rd Sep 1931 | Box 165 \ 4 img104 | |
| Letter chasing North & Sons for a sample 100 M.P.H. magnetic speedometer for an experimental chassis. | 3rd Sep 1931 | Box 165 \ 4 img105 | |
| Testing and cost of a new A.T. type magnetic speedometer from Messrs. North. | 3rd Oct 1931 | Box 165 \ 4 img106 | |
| Follow-up on the supply of a Watford 100 M.P.H. magnetic type speedometer from Messrs. North & Sons. | 3rd Oct 1931 | Box 165 \ 4 img107 | |
| Letter from North & Sons, Ltd. regarding the despatch of a Watford 100 M.P.H. Magnetic Speedometer. | 5th Oct 1931 | Box 165 \ 4 img108 | |
| Inquiry regarding the progress on a Watford 100 M.P.H. Magnetic Tyre Speedometer. | 16th Oct 1931 | Box 165 \ 4 img109 | |
| The procurement of a Watford 100 M.P.H. magnetic speedometer for a test. | 21th Oct 1931 | Box 165 \ 4 img110 | |
| Letter to North & Sons Ltd. requesting the number of revolutions per mile for a sample Watford Magnetic type Speedometer fitted to a 20/25 test car. | 23th Oct 1931 | Box 165 \ 4 img111 | |
| Letter from North & Sons Ltd. confirming the specifications of a sample speedometer at 785 turns per mile. | 24th Oct 1931 | Box 165 \ 4 img112 | |
| The testing of a Watford speedometer for 18-GIV, noting a 3% reading discrepancy. | 26th Oct 1931 | Box 165 \ 4 img113 | |
| Ignition setting test on an 18.G.IV 10,000 miles test car to determine optimum timing. | 26th Oct 1931 | Box 165 \ 4 img114 | |
| The testing and calibration of a Watford speedometer fitted to a car for testing. | 26th Oct 1931 | Box 165 \ 4 img115 | |
| Letter to North & Sons regarding an incorrect length of flexible drive for a Watford Speedometer on a 20/25 HP chassis. | 26th Oct 1931 | Box 165 \ 4 img116 | |
| Exchange of an incorrect length Watford speedometer cable. | 4th Nov 1931 | Box 165 \ 4 img117 | |
| Letter to a customer regarding a failed Watford 100 M.P.H. Speedometer. | 11th Nov 1931 | Box 165 \ 4 img118 | |
| Letter concerning the failure of a sample Watford 100 M.P.H. Magnetic Speedometer during an endurance test. | 11th Nov 1931 | Box 165 \ 4 img119 | |
| Broken Watford speedometer spindle and its temporary replacement. | 13th Nov 1931 | Box 165 \ 4 img120 | |
| Letter from North & Sons, Ltd. acknowledging a letter regarding a broken sample speedometer and arranging for a replacement to be sent for testing. | 14th Nov 1931 | Box 165 \ 4 img121 | |
| Query regarding a Watford 100 M.P.H. Magnetic Speedometer fitted to car 18-G4. | 25th Nov 1931 | Box 165 \ 4 img122 | |
| The testing and issues with a Watford magnetic speedometer. | 30th Nov 1931 | Box 165 \ 4 img123 | |
| Letter from North & Sons, Ltd. regarding the dispatch of a sample speedometer. | 1st Dec 1931 | Box 165 \ 4 img124 | |
| To G.W. Hancock regarding the replacement of a failed Watford speedometer for car 18-GIV. | 4th Dec 1931 | Box 165 \ 4 img125 | |
| Requesting the despatch of a Watford speedometer to France for testing on vehicle 18-GMV. | 4th Dec 1931 | Box 165 \ 4 img126 | |
| Letter to Dobbie, Mc Innes & Clyde Ltd. inquiring about improvements to their 'Fanboro' type electrical indicators. | 8th Dec 1931 | Box 165 \ 4 img127 | |
| Letter to Dobbie McInnes & Clyde Ltd requesting particulars for maximum pressure indicators. | 10th Dec 1931 | Box 165 \ 4 img128 | |
| Quotation from Dobbie McInnes & Clyde Ltd for a 'Farnboro' Electric Indicator'. | 10th Dec 1931 | Box 165 \ 4 img129 | |
| Quotation from Dobbie McInnes & Clyde Ltd for a 'Farnboro' Electric Maximum Pressure Gauge and associated components. | 12th Dec 1931 | Box 165 \ 4 img130 | |
| Request to order a Dobbie-McInnes Farnboro' Electric Maximum Pressure Gauge due to new test regulations. | 14th Dec 1931 | Box 165 \ 4 img131 | |
| Letter to Messrs Dobbie McInnes & Clyde Ltd acknowledging receipt of correspondence and a booklet for a 'Farnboro' Electric Indicator'. | 14th Dec 1931 | Box 165 \ 4 img132 | |
| Arranging the despatch of loaned electrical equipment back to the Chief Superintendent at R.A.E. Farnborough. | 15th Dec 1931 | Box 165 \ 4 img133 | |
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