| Description | Date | Identifier | |
| Letter from S. Smith & Sons concerning modifications to a dial and case arrangement for gauges. | 17th Dec 1938 | Box 175 \ 5 img062 | |
| Letter to S. Smith & Sons Ltd. about returning a defective thermometer and oil gauge unit for repair. | 17th Dec 1938 | Box 175 \ 5 img063 | |
| Letter from S. Smith & Sons regarding a broken hairspring on a Thermometer and Oil Gauge No.703 and the corrective action taken. | 23th Dec 1938 | Box 175 \ 5 img064 | |
| Works order for the repair of a combined oil gauge and thermometer for chassis WXA-47. | 31th Jan 1939 | Box 175 \ 5 img065 | |
| Chasing outstanding repairs for calorstats, oil gauges, and thermometers for specific chassis numbers. | 17th Feb 1939 | Box 175 \ 5 img066 | |
| Official order be sent to Messrs. S. Smith & Sons Ltd for a component conversion. | 23th Feb 1939 | Box 175 \ 5 img067 | |
| The despatch of a special thermometer and oil gauge unit to S. Smith & Sons Ltd. | 23th Feb 1939 | Box 175 \ 5 img068 | |
| Letter to S. Smith & Sons Ltd. requesting the conversion of a combined thermometer and oil gauge unit back to standard. | 23th Feb 1939 | Box 175 \ 5 img069 | |
| Letter from S. Smith & Sons regarding a modified Dual Instrument and its expected dispatch date. | 27th Feb 1939 | Box 175 \ 5 img070 | |
| Letter from S. Smith & Sons (Motor Accessories) Ltd regarding the dispatch of a modified Dual Gauge. | 3rd Mar 1939 | Box 175 \ 5 img071 | |
| Return of three failed Negretti & Zambra thermometers for repair. | 8th Mar 1939 | Box 175 \ 5 img072 | |
| The purchase of one dozen glass thermometers from Messrs. George Ltd. | 10th Mar 1939 | Box 175 \ 5 img073 | |
| Requesting the calibration check of Negretti & Zambra thermometers. | 25th Mar 1939 | Box 175 \ 5 img074 | |
| Letter from S. Smith & Sons regarding the despatch and specifications of a Calorstat for testing. | 25th Mar 1939 | Box 175 \ 5 img075 | |
| Letter from S. Smith & Sons regarding a report and estimate for a combined oil gauge and thermometer from chassis GRP-23. | 27th Mar 1939 | Box 175 \ 5 img076 | |
| Correspondence from S. Smith & Sons regarding a rejected repair claim for a combined oil gauge and thermometer from chassis GRP-23. | 27th Mar 1939 | Box 175 \ 5 img077 | |
| Estimate from S. Smith & Sons for repairing a safety gauge chassis. | 27th Mar 1939 | Box 175 \ 5 img078 | |
| Letter from a supplier regarding a faulty combined oil and radiator thermometer and its free of charge replacement. | 31th Mar 1939 | Box 175 \ 5 img079 | |
| Letter from S. Smith & Sons regarding the repair of a combined oil gauge and radiator thermometer for chassis GGR-5. | 11th Apr 1939 | Box 175 \ 5 img080 | |
| Requesting two N. & Z. thermometers be sent away for repair. | 27th Apr 1939 | Box 175 \ 5 img081 | |
| Request to fabricate a copper top water pipe with an adaptor for a Negretti & Zambra Thermometer. | 10th May 1939 | Box 175 \ 5 img082 | |
| Requesting a check on N. & Z. Thermometers. | 12th Jun 1939 | Box 175 \ 5 img083 | |
| Requesting an N. & Z. thermometer with serial number NT.17435 be sent for repair. | 13th Jun 1939 | Box 175 \ 5 img084 | |
| Cover letter from AMAL LTD enclosing an Oil Thermometer Pocket List. | 3rd Jul 1939 | Box 175 \ 5 img085 | |
| Product specification sheet for an AMAL Type 184 Aircraft Thermometer (Oil) Pocket. | 1st Apr 1939 | Box 175 \ 5 img086 | |
| Product data sheet for an aircraft thermometer oil pocket, detailing specifications and available sizes. | 1st Apr 1939 | Box 175 \ 5 img087 | |
| Order request for a non-luminous oil temperature thermometer from Messrs. Negretti & Zambra Ltd. | 9th Jul 1928 | Box 175 \ 6 img001 | |
| Urgent request to De Havilland Ltd. for a replacement transmitting thermometer. | 25th Jan 1929 | Box 175 \ 6 img002 | |
| Proposed modification to the 'SS' engine oil level indicator to correct its readings. | 1st Feb 1929 | Box 175 \ 6 img003 | |
| Drawings and alterations for an oil sump filter and oil level indicator. | 17th Dec 1928 | Box 175 \ 6 img004 | |
| Blueprint showing the correct graduation for a gauge marked in Gallons. | 11th Feb 1929 | Box 175 \ 6 img005 | |
| Modifications to the SS engine oil level indicator. | 11th Feb 1929 | Box 175 \ 6 img006 | |
| The order of a Negretti & Zambra transmitting pressure gauge. | 5th Mar 1929 | Box 175 \ 6 img007 | |
| Practicality of methods for measuring air intake temperatures on supercharged engines. | 22th Mar 1929 | Box 175 \ 6 img008 | |
| Modification to the float level ratio for the SS. oil level indicator. | 2nd Feb 1929 | Box 175 \ 6 img009 | |
| The correct calibration and clearance checks for the S.S. engine oil level indicator. | 1st Apr 1928 | Box 175 \ 6 img010 | |
| Blueprint detailing the correct calibration for an engine oil level indicator gauge. | 8th Apr 1929 | Box 175 \ 6 img011 | |
| Suggestion to change the markings on the 'SS' oil level indicator from 0.25 gallon increments to 0.5 gallon increments. | 11th Apr 1929 | Box 175 \ 6 img012 | |
| Letter to the Air Ministry regarding a scheme to fit a Negretti and Zambra remote oil pressure gauge to an H. Engine. | 29th Jan 1931 | Box 175 \ 6 img013 | |
| Letter to the Air Ministry suggesting improvements to a Negretti and Zambra transmitting oil pressure gauge. | 19th Feb 1931 | Box 175 \ 6 img014 | |
| To order transmitting pressure gauges for experimental aero test beds. | 5th Feb 1933 | Box 175 \ 6 img015 | |
| Test conducted to determine the effect of altitude on Cambridge and Negretti & Zambra thermometers. | 20th May 1933 | Box 175 \ 6 img016 | |
| Graph showing the effect of altitude (20,000ft) on the gauge reading of a Cambridge Ether Thermometer. | 19th May 1933 | Box 175 \ 6 img017 | |
| Proposed new design for an oil drain cock for the Peregrine 2 engine. | 12th Nov 1932 | Box 175 \ 6 img018 | |
| Explaining the delay in design work for the Peregrine drain cock. | 13th Dec 1932 | Box 175 \ 6 img019 | |
| Revised design for the Peregrine engine's oil drain cock and oil level device. | 2nd Jan 1933 | Box 175 \ 6 img020 | |
| Requesting the trial production of a new Peregrine Oil Sump Drain Cock with a combined oil level indicator. | 3rd Jan 1933 | Box 175 \ 6 img021 | |
| Official order for a 60 lb. Oil Gauge for a Bentley. | 2nd Jan 1935 | Box 175 \ 6 img022 | |
| Failed Spectre oil gauge with concave dials being sent for repair. | 15th May 1935 | Box 175 \ 6 img023 | |
| Advertisement and technical explanation for the King-Seeley Equable Reading Gasoline Gauge. | 28th Mar 1936 | Box 175 \ 6 img024 | |
| Installation of an electrical oil supply gauge on E.R. Hall's car. | 13th May 1936 | Box 175 \ 6 img025 | |
| Outlining the required characteristics and criteria for a proposed .5' air service gun. | 25th Oct 1939 | Box 176 \ 1 img001 | |
| Comparison of specifications for various machine guns and anti-tank rifles. | 25th Oct 1939 | Box 176 \ 1 img002 | |
| List of questions for the Air Ministry regarding the design priorities and required data for a new weapon system. | 16th Nov 1939 | Box 176 \ 1 img003 | |
| Letter requesting particulars on an experimental 40 mm. gun following a discussion with Sir Hugh Dowding. | 16th Nov 1939 | Box 176 \ 1 img004 | |
| Visit to Vickers' and Bristol Aviation companies to discuss the installation of a 40mm gun. | 20th Nov 1939 | Box 176 \ 1 img005 | |
| Installation of 40mm guns on Bristol Beaufighter and a new experimental bomber. | 20th Nov 1939 | Box 176 \ 1 img006 | |
| Letter to Wing Commander Helmore detailing the development and specifications of a 40 m.m. gun. | 21th Nov 1939 | Box 176 \ 1 img007 | |
| Letter to W. A. Rowbotham arranging a visit to see the 40 mm gun. | 24th Nov 1939 | Box 176 \ 1 img008 | |
| Visit to Boulton & Paul regarding a gun project and its integration into their turrets. | 4th Nov 1939 | Box 176 \ 1 img009 | |
| Minutes of a meeting of the Armament Division discussing the 40mm gun. | 30th Jan 1940 | Box 176 \ 1 img010 | |
| Specifications for a 13.2mm aircraft gun intended to follow the 40mm gun, including production considerations. | 30th Jan 1940 | Box 176 \ 1 img011 | |
| The completion date for a gun prototype and the inspection of other available guns. | 30th Jan 1940 | Box 176 \ 1 img012 | |
| Secret summary of opinions from the Air Force on a gun project and future armament requirements. | 6th Feb 1940 | Box 176 \ 1 img013 | |
| Future aircraft armament options, comparing various gun calibers including the Hispano. | 6th Feb 1940 | Box 176 \ 1 img014 | |
| Letter regarding guns and enclosing a copy of another letter for information. | 18th Apr 1940 | Box 176 \ 1 img015 | |
| Letter to Hives detailing a meeting with Sir Hugh Dowding concerning the development of aircraft guns and flame traps. | 18th Apr 1940 | Box 176 \ 1 img016 | |
| Letter discussing the cause and potential solutions for flame trap burning, addressed to E.W. Hives. | 18th Apr 1940 | Box 176 \ 1 img017 | |
| Letter to Wing Commander Helmore confirming a meeting and requesting information on the efficacy of the 20mm gun for a projected armament programme. | 17th May 1940 | Box 176 \ 1 img018 | |
| Letter to Sir Charles Craven concerning a visit by Sir John Salmond to discuss the 13.2 and 40 mm guns, their priority, and use in aerodrome defence. | 17th Jul 1940 | Box 176 \ 1 img019 | |
| Letter to the Air Ministry requesting material release for the production of 13.2 mm and 40 mm guns. | 1st Jul 1940 | Box 176 \ 1 img020 | |
| Summary of the fighter aircraft armament position, highlighting the need for heavier calibre weapons. | 7th Jul 1940 | Box 176 \ 1 img021 | |
| Optimizing fighter aircraft armament, focusing on gun installations and ammunition capacity. | 7th Jul 1940 | Box 176 \ 1 img022 | |
| Summary questioning the logic behind armament decisions and production for fighter aircraft. | 7th Jul 1940 | Box 176 \ 1 img023 | |
| Secret report on armament schemes for Spitfire and Hurricane aircraft. | 8th Jul 1940 | Box 176 \ 1 img024 | |
| Aircraft armament installations, including various gun types, wing modifications, and turret options. | 8th Jul 1940 | Box 176 \ 1 img025 | |
| Letter to Mr. Robotham regarding Admiral Evans's decision on using the 40mm gun for ground defence. | 8th Jul 1940 | Box 176 \ 1 img026 | |
| Tracing of a Hawker Aircraft Co. drawing showing .303 and .5 bore Browning machine guns mounted in a Hurricane wing. | 12th Jul 1940 | Box 176 \ 1 img027 | |
| Letter regarding aircraft armament, specifically the mounting of guns on Hurricane and Spitfire wings. | 12th Jul 1940 | Box 176 \ 1 img028 | |
| Analyzing various gun sizes and weights, comparing the Hispano and Oerlikon 20mm guns. | 17th Jul 1940 | Box 176 \ 1 img029 | |
| Graph detailing alternative gun installations for a Spitfire aircraft. | 17th Jul 1940 | Box 176 \ 1 img030 | |
| Graph showing weight calculations for alternative gun installations on Spitfire aircraft. | 17th Jul 1940 | Box 176 \ 1 img031 | |
| Graph plotting weight against muzzle velocity and rate of fire for an alternative gun installation on a Spitfire aircraft. | 17th Jul 1940 | Box 176 \ 1 img032 | |
| Blueprint detailing aircraft armament specifications with a top-down schematic. | 17th Jul 1940 | Box 176 \ 1 img033 | |
| Blueprint detailing gun specifications and the wing planform for an aircraft. | 17th Jul 1940 | Box 176 \ 1 img034 | |
| Blueprint of an aircraft showing wing armament layout and gun specifications. | 17th Jul 1940 | Box 176 \ 1 img035 | |
| Blueprint of an aircraft's wing planform detailing its armament specifications. | 17th Jul 1940 | Box 176 \ 1 img036 | |
| Blueprint detailing armament specifications and gun layout for an aircraft. | 17th Jul 1940 | Box 176 \ 1 img037 | |
| Blueprint for an alternative aircraft gun installation, possibly for a Spitfire. | 17th Jul 1940 | Box 176 \ 1 img038 | |
| Blueprint detailing gun specifications and a schematic for a Spitfire aircraft. | 1st Mar 1940 | Box 176 \ 1 img039 | |
| Blueprint showing a top-down view of an aircraft with gun specifications. | 1st Mar 1940 | Box 176 \ 1 img040 | |
| Extract from a letter from Mr. Frise regarding firing tests on a blast tube for the 'Beaufighter' installation. | 23th Jul 1940 | Box 176 \ 1 img041 | |
| Request for up-to-date gun installation drawings for the Beaufighter aircraft. | 23th Jul 1940 | Box 176 \ 1 img042 | |
| Authorization note for the collection of a gun loaned from a Hurricane for return to Hucknall. | 24th Jul 1940 | Box 176 \ 1 img043 | |
| Letter to the Ministry of Aircraft Production regarding firing trials of a 13.2 m/m gun. | 24th Jul 1940 | Box 176 \ 1 img044 | |
| Letter to the Chief Aircraft Designer at Bristol Aircraft Factory regarding the 40 m/m cannon gun. | 25th Jul 1940 | Box 176 \ 1 img045 | |
| Letter from Bristol Aeroplane Company regarding the installation and testing of a 40mm cannon on a Beaufighter aircraft. | 2nd Aug 1940 | Box 176 \ 1 img046 | |
| Letter to de Havilland Engine Co. Ltd. about supplying a special carburettor for a Gipsy VI aero engine. | 8th Aug 1940 | Box 176 \ 1 img047 | |
| Development work and testing for 40mm guns for the Admiralty and the Beaufighter. | 12th Aug 1940 | Box 176 \ 1 img048 | |
| Letter from the Ministry of Aircraft Production requesting information on the progress of the .5 machine gun. | 22th Aug 1940 | Box 176 \ 1 img050 | |
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