| Description | Date | Identifier | |
| Letter to The A.T. Speedometer Co regarding a potential requirement for an experimental instrument. | 11th Dec 1930 | Box 59 \ 2 Scan094 | |
| Testing A.T. speedometers and the problems caused by running them in reverse. | 15th Dec 1930 | Box 59 \ 2 Scan095 | |
| Letter from The A.T. Speedometer Co. Ltd. detailing drive revolutions per mile for speedometers. | 22th Dec 1930 | Box 59 \ 2 Scan096 | |
| Experimental record sheet for a 10,000-mile test on an A.T. Speedometer. | 4th Feb 1930 | Box 59 \ 2 Scan097 | |
| Electrical experimental record sheet for an AT Speedometer, No E.185.785. | 20th Apr 1931 | Box 59 \ 2 Scan098 | |
| Extract from a monthly report on customer's complaints regarding an improved speedometer. | 16th Jan 1931 | Box 59 \ 2 Scan099 | |
| Requesting a laboratory retest for speedometer D.231 740 from vehicle 18-GIV following a 10,000-mile test. | 22th Jan 1931 | Box 59 \ 2 Scan100 | |
| Test report of an AT Speedometer after 10,000 miles, noting reading inaccuracies and a failed trip counter. | 3rd Feb 1931 | Box 59 \ 2 Scan101 | |
| Test record for an A.T. Speedometer. | 3rd Feb 1931 | Box 59 \ 2 Scan102 | |
| The receipt and testing of new production A.T. speedometers. | 8th Feb 1931 | Box 59 \ 2 Scan103 | |
| Letter to A.T. Speedometer Co. regarding modifications and issues with speedometers. | 11th Feb 1931 | Box 59 \ 2 Scan104 | |
| Electrical experimental record sheet for a 10,000-mile test on an A.T. Speedometer. | 10th Oct 1930 | Box 59 \ 2 Scan105 | |
| Persistent inaccuracy of the A.T. Speedometer and the need for a specially graduated dial. | 10th Mar 1931 | Box 59 \ 2 Scan106 | |
| Comparative test results for a 20/25 speedometer EX 18-GIV before and after a 10,000-mile test. | 1st Mar 1931 | Box 59 \ 2 Scan107 | |
| Non-adherence to recommended speedometer revolutions per mile for the Phantom model. | 2nd Mar 1931 | Box 59 \ 2 Scan108 | |
| Wheel revolutions per mile for Phantom A.T. speedometers under various tyre conditions. | 3rd Mar 1931 | Box 59 \ 2 Scan109 | |
| Request for up-to-date information on the A.T. Speedometer for the 20/25 chassis. | 3rd Mar 1931 | Box 59 \ 2 Scan110 | |
| Technical discussion on the accuracy of A.T. speedometers and proposed testing arrangements. | 3rd Mar 1931 | Box 59 \ 2 Scan111 | |
| Tyre dimensions and wheel revolutions per mile for Phantom and 25 HP models, specifically concerning A.T. Speedometers. | 16th Mar 1931 | Box 59 \ 2 Scan112 | |
| Continued report page discussing a 2.5% reduction in road wheel revolutions per mile at high speeds. | 16th Mar 1931 | Box 59 \ 2 Scan113 | |
| Recalibration of A.T. speedometers using a parabolic scale to improve accuracy at higher speeds. | 8th Mar 1931 | Box 59 \ 2 Scan114 | |
| Letter to The A.T. Speedometer Co. inquiring about specific drive revolutions per mile for their speedometers. | 23th Mar 1931 | Box 59 \ 2 Scan115 | |
| Progressive scale contraction on A.T. speedometers for the Phantom II chassis. | 24th Mar 1931 | Box 59 \ 2 Scan116 | |
| Calculations for speedometer gear ratio and revolutions per mile, accounting for tyre pressure and speed effects. | 24th Mar 1931 | Box 59 \ 2 Scan117 | |
| Instrument gear ratios and the adoption of a non-proportional speed scale for a Phantom chassis. | 24th Mar 1931 | Box 59 \ 2 Scan118 | |
| Specifications for the adjustment and testing of speed indicating instruments. | 24th Mar 1931 | Box 59 \ 2 Scan119 | |
| The basis and development for a dis-proportional speed scale on a magnetic eddy current type speedometer. | 23th Mar 1931 | Box 59 \ 2 Scan120 | |
| Analysis of potential speedometer issues and the application of the law of speed scale contraction. | 23th Mar 1931 | Box 59 \ 2 Scan121 | |
| Explaining the practical basis for speedometer scale contraction to compensate for the increase in tyre diameter at high speeds. | 23th Mar 1931 | Box 59 \ 2 Scan122 | |
| Mathematical development of the law of speed scale contraction relating to tyre diameter and road speed. | 23th Mar 1931 | Box 59 \ 2 Scan123 | |
| Page of mathematical formulae for calculating the revolutions and deflection of a speedometer drive. | 23th Mar 1931 | Box 59 \ 2 Scan124 | |
| Page detailing the mathematical calculations for correcting a speedometer scale. | 23th Mar 1931 | Box 59 \ 2 Scan125 | |
| Data table for calculating the placement of divisions on a contracted scale from an original proportional scale. | 23th Mar 1931 | Box 59 \ 2 Scan126 | |
| The arguments for applying the law of speed scale contraction to speedometers, both with and without mile counters. | 23th Mar 1931 | Box 59 \ 2 Scan127 | |
| The calibration of speed and mileage indicators, considering accuracy at different speeds. | 23th Mar 1931 | Box 59 \ 2 Scan128 | |
| Calculations for modifying speedometer scale indications to account for various factors. | 23th Mar 1931 | Box 59 \ 2 Scan129 | |
| Data table for converting speed readings between a proportional scale and a new contract scale. | 23th Mar 1931 | Box 59 \ 2 Scan130 | |
| Speedometer calibration, considering gear ratios and the centrifugal effect on tyres at speed. | 26th Mar 1931 | Box 59 \ 2 Scan131 | |
| Letter from a speedometer supplier discussing achievable revolutions per mile for total and trip instruments. | 26th Mar 1931 | Box 59 \ 2 Scan132 | |
| Alteration of gear ratios for A.T. Speedometers to achieve accurate readings. | 27th Mar 1931 | Box 59 \ 2 Scan133 | |
| Letter to A.T. Speedometer Co. Ltd. regarding the incorrect testing and a mechanical error with two special speedometers. | 27th Mar 1930 | Box 59 \ 2 Scan134 | |
| Speedometer calibration issues for the Phantom model and updating the instrument specifications. | 1st Apr 1931 | Box 59 \ 2 Scan135 | |
| Instructions for instrument makers on the adjustment and calibration of a speed indicating instrument. | 1st Apr 1931 | Box 59 \ 2 Scan136 | |
| Sample magnetic speedometer from Watford, comparing its cost and features to the existing A.T. Speedometer. | 6th May 1931 | Box 59 \ 2 Scan137 | |
| Test record for a Watford speedometer, showing performance at various temperatures. | 9th Jun 1931 | Box 59 \ 2 Scan138 | |
| Calibration of an A.T. speedometer for a Smith instrument board. | 6th Jan 1932 | Box 59 \ 2 Scan139 | |
| Order for an A.T. speedometer from Smiths for an experimental 40/50 chassis. | 7th Mar 1932 | Box 59 \ 2 Scan140 | |
| Letter of complaint regarding an inaccurate A.T. speedometer and requesting readjustment. | 23th Mar 1932 | Box 59 \ 2 Scan141 | |
| Calibration figures for A.T. Speedometer No. 527. | 23th Mar 1932 | Box 59 \ 2 Scan142 | |
| The dispatch of an A.T. speedometer for examination and correction. | 23th Mar 1932 | Box 59 \ 2 Scan143 | |
| Letter regarding a faulty speedometer head, detailing damage and a gearing discrepancy. | 4th Apr 1932 | Box 59 \ 2 Scan144 | |
| Letter to The A.T. Speedometer Co. regarding a persistent speedometer scale discrepancy. | 8th Apr 1932 | Box 59 \ 2 Scan145 | |
| Letter from The A.T. Speedometer Co. Ltd. regarding a suspected discrepancy with a speedometer head. | 11th Apr 1932 | Box 59 \ 2 Scan146 | |
| The exchange of a Smith A.T. Speedometer for one with different specifications. | 11th Apr 1932 | Box 59 \ 2 Scan147 | |
| Requesting the alteration of a speedometer's revolutions per mile setting due to a change in tyre size for car 19-GIV. | 4th Apr 1932 | Box 59 \ 2 Scan148 | |
| Request to modify speedometer No. 780 for car 17.G.4 to suit a new gearbox and 11/50 axle ratio. | 20th Apr 1932 | Box 59 \ 2 Scan149 | |
| Letter to The A.T. Speedometer Co. regarding required speedometer calibration adjustments. | 27th Apr 1932 | Box 59 \ 2 Scan150 | |
| Letter from The A.T. Speedometer Co. Ltd. regarding the calibration of 80 mph instruments to read 5% fast. | 29th Apr 1932 | Box 59 \ 2 Scan151 | |
| Alteration to an A.T. speedometer to change the revs per mile figure from 810 to 864. | 1st May 1932 | Box 59 \ 2 Scan152 | |
| Requesting the return of a speedometer to have the 'revs per mile' figure altered. | 23th May 1932 | Box 59 \ 2 Scan153 | |
| Speedometer accuracy and calibration for the 20/25 Chassis U Series. | 23th May 1932 | Box 59 \ 2 Scan154 | |
| Returning 24 accumulated speedometers from the Experimental Shop to their makers. | 24th May 1932 | Box 59 \ 2 Scan155 | |
| Letter to A.T. Speedometer Co. Ltd. regarding a speedometer reading faster than the agreed-upon tolerance. | 28th May 1932 | Box 59 \ 2 Scan156 | |
| Letter from The A.T. Speedometer Co. acknowledging receipt of an A.T. Speedometer for testing. | 30th May 1932 | Box 59 \ 2 Scan157 | |
| Letter from The A.T. Speedometer Co. regarding a sample Group Type Speedometer sent for testing. | 7th Jun 1932 | Box 59 \ 2 Scan158 | |
| Excessive error in speedometers for the 20/25HP 'U' Series chassis. | 7th Jun 1932 | Box 59 \ 2 Scan159 | |
| Speedometer requirements, calibration, verbal specification, and ordering for different car models. | 8th Jun 1932 | Box 59 \ 2 Scan160 | |
| Letter regarding the inspection and proposed scrapping of 22 obsolete speedometers by the A.T. Speedometer Company. | 9th Jun 1932 | Box 59 \ 2 Scan161 | |
| Letter to A.T. Speedometer Co. Ltd. regarding the testing and approval of a new speedometer for a 20/25 HP chassis. | 9th Jun 1932 | Box 59 \ 2 Scan162 | |
| Letter from The A.T. Speedometer Co., Ltd. regarding the adjustment of an instrument and commitments for a Veeder type recorder. | 11th Jun 1932 | Box 59 \ 2 Scan163 | |
| Letter from the A.T. Speedometer Co. about dispatching a new type of speedometer for a 20/25 HP chassis. | 21th Jun 1932 | Box 59 \ 2 Scan164 | |
| Request for a speedometer blueprint for the experimental 'Peregrine' chassis. | 29th Jun 1932 | Box 59 \ 2 Scan165 | |
| Letter from the A.T. Speedometer Co. regarding the testing of instrument F.429, refuting a claimed error and providing detailed test results. | 29th Jun 1932 | Box 59 \ 2 Scan166 | |
| Letter to A.T. Speedometer Co. Ltd. with retest results for speedometer No. F429. | 6th Jul 1932 | Box 59 \ 2 Scan167 | |
| Letter discussing test results for an instrument, comparing M.P.H. and R.P.M. figures. | 9th Jul 1932 | Box 59 \ 2 Scan168 | |
| Letter from a supplier regarding the failure of a new mileage recorder during testing. | 9th Jul 1932 | Box 59 \ 2 Scan169 | |
| Letter to A.T. Speedometer Co. Ltd regarding the testing of a sample speedometer with a faulty trip recorder. | 11th Jul 1932 | Box 59 \ 2 Scan170 | |
| Clarification on the supply of a dual scale speedometer dial for the 20/25 HP model. | 10th Aug 1932 | Box 59 \ 2 Scan171 | |
| Alteration of a speedometer for chassis 18.G.IV due to a new experimental axle. | 11th Aug 1932 | Box 59 \ 2 Scan172 | |
| Returning a tested A.T. Speedometer with a new type of mileage recorder. | 17th Aug 1932 | Box 59 \ 2 Scan173 | |
| Letter to The A.T. Speedometer Co. regarding the failure of a new type of mileage recorder during a 20,000-mile test. | 17th Aug 1932 | Box 59 \ 2 Scan174 | |
| Letter from A.T. Speedometer Co. regarding a failed trip recorder on a speedometer after a 20,000-mile test. | 19th Aug 1932 | Box 59 \ 2 Scan175 | |
| Letter from The A.T. Speedometer Co. arranging a meeting to discuss proposed new mileage on their instruments. | 5th Sep 1932 | Box 59 \ 2 Scan176 | |
| Letter concerning a cracked disc on a test speedometer and a request for a further prolonged test of the instrument. | 16th Sep 1932 | Box 59 \ 2 Scan177 | |
| Letter to A.T. Speedometer Co. regarding the re-testing of an instrument with an erratic running issue. | 20th Sep 1932 | Box 59 \ 2 Scan178 | |
| Letter from The A.T. Speedometer Co. acknowledging an agreement to re-test an instrument. | 21th Sep 1932 | Box 59 \ 2 Scan179 | |
| Discrepancy in the speedometer calibration for the Peregrine chassis. | 24th Sep 1932 | Box 59 \ 2 Scan180 | |
| Recommendation to fit a new A.T. Speedometer Co. total mileage recorder following successful endurance testing. | 24th Nov 1932 | Box 59 \ 2 Scan181 | |
| Letter to The A.T. Speedometer Co. confirming satisfactory tests of a new total mileage recorder for the 20/25 HP model. | 24th Nov 1932 | Box 59 \ 2 Scan182 | |
| Letter from The A.T. Speedometer Co., Ltd. regarding stock levels of Veeder Mileage Recorders for the 20/25HP and 40/50HP models. | 28th Nov 1932 | Box 59 \ 2 Scan183 | |
| Confirming arrangements to alter one speedometer and order another to accommodate two different axle ratios for a car. | 6th Feb 1933 | Box 59 \ 2 Scan184 | |
| Telegram received by telephone concerning the return of a special speedometer to St Pancras. | 7th Jul 1933 | Box 59 \ 2 Scan185 | |
| Letter from the A.T. Speedometer Co., Ltd. confirming a telegram about a returned speedometer and a new order. | 7th Feb 1933 | Box 59 \ 2 Scan186 | |
| Invoice from The A.T. Speedometer Co. Ltd. for parts related to experimental work. | 23th Feb 1933 | Box 59 \ 2 Scan187 | |
| Further cost information on a Bensport Rev Indicator and Speedometer. | 28th Feb 1933 | Box 59 \ 2 Scan188 | |
| The overhaul and recalibration of A.T. speedometers. | 17th Mar 1933 | Box 59 \ 2 Scan189 | |
| Request to obtain quotations and a sample speedometer and rev counter from Messrs Norths' for the Bensport model. | 24th Mar 1933 | Box 59 \ 2 Scan190 | |
| Letter to The A.T. Speedometer Co. Ltd. regarding a new speedometer for a Bentley chassis and the return of faulty parts. | 2nd May 1933 | Box 59 \ 2 Scan191 | |
| The required alterations for a Bensport speedometer, including changes to the revs per mile and scale accuracy. | 9th May 1933 | Box 59 \ 2 Scan192 | |
| Calibration arrangements for Bensport speedometers based on different axle and tyre configurations. | 11th May 1933 | Box 59 \ 2 Scan193 | |
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