| Description | Date | Identifier | |
| Letter requesting remarks on charges before settling an invoice for two units. | 16th May 1938 | Box 156 \ 2 scan0093 | |
| Price list for various thermostat models, detailing specific orders from January to May 1938. | 16th May 1938 | Box 156 \ 2 scan0094 | |
| Letter from a supplier discussing charges for sample thermostats and offering a loan arrangement for experimental units. | 19th May 1938 | Box 156 \ 2 scan0095 | |
| Request to send a covering order for 6 sample bellows to The Drayton Regulator & Instrument Co.Ltd. | 20th May 1938 | Box 156 \ 2 scan0096 | |
| Request for a covering order for 6 sample bellows to be sent to The Drayton Regulator & Instrument Co.Ltd. | 20th May 1938 | Box 156 \ 2 scan0097 | |
| Letter to The Drayton Regulator & Instrument Co. Ltd regarding pricing and a request for sample bellows. | 20th May 1938 | Box 156 \ 2 scan0098 | |
| Letter to S. Smith & Sons Ltd. regarding charges for experimental thermostat units and drawings for a heater. | 21th May 1938 | Box 156 \ 2 scan0099 | |
| Letter from S. Smith & Sons regarding the transfer of two thermostats to a loan account. | 24th May 1938 | Box 156 \ 2 scan0100 | |
| Requesting the return of a thermostat for modification by the British Thermostat Co. | 25th May 1938 | Box 156 \ 2 scan0101 | |
| Letter to The British Thermostat Co. Ltd. regarding the acceptance of an undersized thermostat order and the return of a sample for adjustment. | 25th May 1938 | Box 156 \ 2 scan0102 | |
| Postscript regarding a distorted bellows unit with a dropped open setting temperature. | 25th May 1938 | Box 156 \ 2 scan0103 | |
| Letter regarding pressure testing of a Bentley thermostat unit and performance of heater motor rheostats. | 25th Apr 1938 | Box 156 \ 2 scan0104 | |
| Letter to S.Smith & Sons Ltd requesting details on an S.U. carburetter thermostatic control and the return of a Hadees car heater. | 26th May 1938 | Box 156 \ 2 scan0105 | |
| Letter from The British Thermostat Co., Ltd. regarding thermostats, associated drawings, and an agreement to use up existing stock. | 26th May 1938 | Box 156 \ 2 scan0106 | |
| Request to detail and instruct an adaptor for fitting a thermostat into a Bentley III thermostat casing. | 26th May 1938 | Box 156 \ 2 scan0107 | |
| Letter to The British Thermostat Co. Ltd. regarding failures in a thermostat unit due to metal particles on the magnet. | 27th May 1938 | Box 156 \ 2 scan0108 | |
| Letter regarding a buckled thermostat frame and adjustments to its opening temperature. | 27th May 1938 | Box 156 \ 2 scan0109 | |
| Letter from The Drayton Regulator and Instrument Company Ltd. to Bentleys Motors Ltd. regarding thermostatic units for motor car radiators. | 10th Jun 1938 | Box 156 \ 2 scan0110 | |
| Letter to The Drayton Regulator & Instrument Co. Ltd. regarding a proposal for a replica Harrison thermostat. | 15th Jun 1938 | Box 156 \ 2 scan0111 | |
| Letter from The Drayton Regulator and Instrument Co. Ltd regarding a misdirected communication and the return of a Harrison unit. | 16th Jun 1938 | Box 156 \ 2 scan0112 | |
| Request to obtain, modify, and fit a Bentley 'M' series production thermostat housing to assembly 6.B.IV. | 22th Jun 1938 | Box 156 \ 2 scan0113 | |
| New drawings and required parts for a Bentley 111 Thermostat Unit. | 1st Jul 1938 | Box 156 \ 2 scan0114 | |
| Letter from Wilmot-Breeden Ltd. regarding a sample wax-filled thermostat tube with a melting point of 85 degrees Centigrade. | 21th Jul 1938 | Box 156 \ 2 scan0115 | |
| Request to despatch two faulty thermostats to the British Thermostat Co. Ltd. for rectification. | 25th Aug 1938 | Box 156 \ 2 scan0116 | |
| Discrepancy between the drawing and the manufactured 'M' Series Bentley Thermostat Casing. | 25th Aug 1938 | Box 156 \ 2 scan0117 | |
| Return of a faulty production thermostat to the supplier, The British Thermostat Co. | 31th Aug 1938 | Box 156 \ 2 scan0118 | |
| Return of two faulty thermostats to the supplier for correction and subsequent return to production stock. | 7th Sep 1938 | Box 156 \ 2 scan0119 | |
| Thermostat issues and revised settings for the Bentley M series chassis. | 7th Sep 1938 | Box 156 \ 2 scan0120 | |
| Complaint letter to The British Thermostat Co. Ltd. regarding thermostat units not meeting the specified temperature limits. | 7th Sep 1938 | Box 156 \ 2 scan0121 | |
| Letter to The British Thermostat Co. Ltd. outlining thermostat testing procedures and returning defective units. | 7th Sep 1938 | Box 156 \ 2 scan0122 | |
| Letter regarding the testing of two thermostats, model EB.3509, one of which was found to be faulty. | 12th Sep 1938 | Box 156 \ 2 scan0123 | |
| Letter from The British Thermostat Co. Ltd. regarding issues with adjusting thermostat spindles and confirming unit prices. | 14th Sep 1938 | Box 156 \ 2 scan0124 | |
| Letter to The British Thermostat Co. Ltd. regarding the practice of pinning the spindle on thermostats. | 14th Sep 1938 | Box 156 \ 2 scan0125 | |
| Return of three Smith's thermostats to the manufacturer for alteration. | 15th Sep 1938 | Box 156 \ 2 scan0126 | |
| Letter to S. Smith & Sons Ltd. regarding the return and re-setting of three thermostats. | 15th Sep 1938 | Box 156 \ 2 scan0127 | |
| Letter from S. Smith & Sons regarding the return of three calibrated thermostats for the attention of Mr. C.S. Steadman. | 17th Sep 1938 | Box 156 \ 2 scan0128 | |
| Letter to The British Thermostat Co. Ltd. seeking comment on a suggestion for thermostat inspection. | 22th Sep 1938 | Box 156 \ 2 scan0129 | |
| Letter from The British Thermostat Co. Ltd. regarding a manufacturing and testing difficulty with Bentley Thermostats and the new jig created to resolve it. | 24th Sep 1938 | Box 156 \ 2 scan0130 | |
| Letter from The British Thermostat Co. Ltd. responding to an enquiry about Part No. E.18650, advising against a specification for extending bellows. | 3rd Oct 1938 | Box 156 \ 2 scan0131 | |
| Dispatch of a faulty Callorstat from chassis GRO-52 for examination. | 3rd Oct 1938 | Box 156 \ 2 scan0132 | |
| Faulty Callorstat from chassis GXM-60 being sent for examination. | 3rd Oct 1938 | Box 156 \ 2 scan0133 | |
| The repair and replacement procedure for faulty thermostats and thermometers. | 29th Sep 1938 | Box 156 \ 2 scan0134 | |
| Returned calorstat from chassis GRP-38, supplied by Dex Garages, Ltd. | 5th Oct 1938 | Box 156 \ 2 scan0135 | |
| The examination of a Calorstat from chassis GRP-38 for Dex Garages. | 7th Oct 1938 | Box 156 \ 2 scan0136 | |
| Responding to complaints about calorstats on chassis GXM.60 & GRO.52, detailing test results and concluding the issue is likely sticking shutters. | 6th Oct 1938 | Box 156 \ 2 scan0137 | |
| Dispatch of two calorstats to be returned for alteration to their settings. | 6th Oct 1938 | Box 156 \ 2 scan0138 | |
| Letter to a supplier regarding complaints and specification ambiguity for calorstats. | 6th Oct 1938 | Box 156 \ 2 scan0139 | |
| Letter requesting the alteration of settings on two returned units to test for potential cost reduction. | 6th Oct 1938 | Box 156 \ 2 scan0140 | |
| Clarifying the return procedure for faulty calorstats and thermometers involving the supplier S. Smith & Sons Ltd. | 8th Oct 1938 | Box 156 \ 2 scan0141 | |
| Letter from British Thermostat Co. proposing a design modification to prevent drill breakages during the manufacture of the Bentley Thermostat. | 10th Oct 1938 | Box 156 \ 2 scan0142 | |
| The second page of a letter from The British Thermostat Co. Ltd. | 12th Oct 1938 | Box 156 \ 2 scan0143 | |
| Letter from S. Smith & Sons discussing the load and temperature performance of shutter 'calostats'. | 12th Oct 1938 | Box 156 \ 2 scan0144 | |
| Letter to The British Thermostat Co. Ltd. regarding a proposed modification to a spindle. | 12th Oct 1938 | Box 156 \ 2 scan0145 | |
| Dealing with thermometers, including sourcing from Smiths' direct and requesting more stock. | 13th Oct 1938 | Box 156 \ 2 scan0146 | |
| Letter from The British Thermostat Co. Ltd. regarding a spindle sent for approval. | 14th Oct 1938 | Box 156 \ 2 scan0147 | |
| Letter to The British Thermostat Co. Ltd. agreeing to the modification of all spindles after a successful sample. | 18th Oct 1938 | Box 156 \ 2 scan0148 | |
| Letter to S. Smith & Sons Ltd. regarding the testing and return of calorstat units for Bentley cars. | 19th Oct 1938 | Box 156 \ 2 scan0149 | |
| Letter regarding a modified sample spindle, advising the recipient to carry out the work due to having no stock. | 19th Oct 1938 | Box 156 \ 2 scan0150 | |
| Letter to The British Thermostat Co. Ltd. regarding unsatisfactory rheostat samples and sourcing of alternative parts. | 31th Oct 1938 | Box 156 \ 2 scan0151 | |
| Letter from The British Thermostat Co. explaining a delay and incompatibility with a thermostat fitted with diaphragm bellows. | 9th Nov 1938 | Box 156 \ 2 scan0152 | |
| Page two of a letter from The British Thermostat Co. Ltd. | 11th Nov 1938 | Box 156 \ 2 scan0153 | |
| Request to place an order for thermostats from S. Smith & Sons Ltd. | 11th Nov 1938 | Box 156 \ 2 scan0154 | |
| Letter from S. Smith & Sons regarding the testing and modification of shutter operating thermostat samples. | 15th Nov 1938 | Box 156 \ 2 scan0155 | |
| Letter from the Experimental Department returning 3 failed calorstats and requesting a report on the cause of failure. | 17th Nov 1938 | Box 156 \ 2 scan0156 | |
| Letter from S. Smith & Sons regarding the examination and reconditioning of returned calostats. | 18th Nov 1938 | Box 156 \ 2 scan0157 | |
| Letter to The British Thermostat Co. Ltd. discussing the reliability and testing of diaphragm bellows for a thermostat unit. | 24th Nov 1938 | Box 156 \ 2 scan0158 | |
| Letter from S. Smith & Sons regarding test results for three returned calorstats. | 24th Nov 1938 | Box 156 \ 2 scan0159 | |
| Test results for four returned calorstats from different chassis. | 24th Nov 1938 | Box 156 \ 2 scan0160 | |
| Letter from The British Thermostat Co., Ltd. regarding the suitability of diaphragm type bellows versus spun bellows for a thermostat. | 28th Nov 1938 | Box 156 \ 2 scan0161 | |
| Requesting the return of repaired Callorstats due to a stock shortage. | 1st Dec 1938 | Box 156 \ 2 scan0162 | |
| Letter from S. Smith & Sons regarding the performance of a 'Smithermet' Radiator Shutter filled with Hexane. | 2nd Dec 1938 | Box 156 \ 2 scan0163 | |
| Letter to S. Smith & Sons Ltd. regarding the return of six defective calorstats for repair. | 5th Dec 1938 | Box 156 \ 2 scan0164 | |
| Letter from S. Smith & Sons regarding the return and reconditioning of six faulty Calorstats. | 7th Dec 1938 | Box 156 \ 2 scan0165 | |
| Letter from The British Thermostat Co., Ltd. regarding a thermostat for an 'SU' Starting Carburetter. | 12th Dec 1938 | Box 156 \ 2 scan0166 | |
| Letter from The British Thermostat Co. Ltd. discussing a modification to an 'SK' Refrigeration Thermostat. | 21th Dec 1938 | Box 156 \ 2 scan0167 | |
| Letter from S. Smith & Sons regarding the testing, reconditioning, and return of six 'calorstat' units. | 21th Dec 1938 | Box 156 \ 2 scan0168 | |
| Letter from The British Thermostat Co., Ltd. regarding different types of thermostats, referencing an article in 'The Motor'. | 23th Dec 1938 | Box 156 \ 2 scan0169 | |
| Technical information sheet discussing the merits of by-pass versus non-by-pass motor car thermostats. | 13th Jul 1928 | Box 156 \ 2 scan0170 | |
| The function of engine cooling by-pass systems and general observations on bellows thermostats. | 28th Dec 1938 | Box 156 \ 2 scan0171 | |
| Sending a thermostat unit for examination and repair to the British Thermostat Co. Ltd. | 28th Dec 1938 | Box 156 \ 2 scan0172 | |
| Letter to the British Thermostat Co. Ltd. returning a failed thermostat unit for repair and requesting a failure report. | 28th Dec 1938 | Box 156 \ 2 scan0173 | |
| Letter from The British Thermostat Co. Ltd. acknowledging the return of a failed thermostat unit. | 29th Dec 1938 | Box 156 \ 2 scan0174 | |
| Calorstat from chassis B.55-LE sent for examination. | 31th Dec 1938 | Box 156 \ 2 scan0175 | |
| Instructing the despatch of a calorstat unit to S. Smith & Sons Ltd for Mr. Eckford. | 2nd Jan 1939 | Box 156 \ 2 scan0176 | |
| Letter to S. Smith & Sons Ltd. concerning the return of a defective calorstat for examination and repair. | 2nd Jan 1939 | Box 156 \ 2 scan0177 | |
| Letter from The British Thermostat Co. Ltd. explaining the failure of a Bentley Thermostat bellows. | 14th Jan 1939 | Box 156 \ 2 scan0178 | |
| Invoice for a carburetter thermostat from The British Thermostat Co. Ltd and requesting payment authorization. | 16th Jan 1939 | Box 156 \ 2 scan0179 | |
| Request to send an official order for an S.U. Carburetter Thermostat to The British Thermostat Co. Ltd. | 19th Jan 1939 | Box 156 \ 2 scan0180 | |
| Outlining a new procedure for returning failed thermometers, calorstats, and thermostats directly to the makers. | 2nd Feb 1939 | Box 156 \ 2 scan0181 | |
| Follow-up letter to S. Smith & Sons Ltd. regarding the repair and return of three calorstats. | 3rd Feb 1939 | Box 156 \ 2 scan0182 | |
| Repair process for thermostats and a proposal to deal directly with the makers. | 4th Feb 1939 | Box 156 \ 2 scan0183 | |
| Identifying the makers of faulty thermostats for direct repair. | 6th Feb 1939 | Box 156 \ 2 scan0184 | |
| Discontinuing the practice of testing allegedly faulty instruments like thermometers and thermostats before returning them to makers. | 6th Feb 1939 | Box 156 \ 2 scan0185 | |
| Letter to S. Smith & Sons Ltd. regarding the testing of a 'Hexane' filled calorstat that operates at a lower temperature than the standard. | 6th Feb 1939 | Box 156 \ 2 scan0186 | |
| The process for handling failure reports for thermometers or thermostats from Smiths'. | 7th Feb 1939 | Box 156 \ 2 scan0187 | |
| Letter from S. Smith & Sons regarding performance issues with 'Hexane' filled thermostats and bellows. | 7th Feb 1939 | Box 156 \ 2 scan0188 | |
| Letter from S. Smith & Sons regarding the return of three tested Calorstats E. 80893. | 8th Feb 1939 | Box 156 \ 2 scan0189 | |
| Scrapped calorstat for Bentley Chassis B.55.LE, requesting confirmation and billing details for a replacement. | 10th Feb 1939 | Box 156 \ 2 scan0190 | |
| Calorstat for chassis GRP.38 of Dex Garages Ltd. | 10th Feb 1939 | Box 156 \ 2 scan0191 | |
| Return of a special Hexane filled calorstat to S. Smith & Sons for alteration. | 15th Feb 1939 | Box 156 \ 2 scan0192 | |
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