| Description | Date | Identifier | |
| Instruction to continue supplying louvred bonnets to 40/50 HP chassis destined for hot countries. | 30th Aug 1927 | Box 119 \ 3 scan0104 | |
| Design of bonnet shutters versus louvres for the 'Phantom' model. | 17th Sep 1927 | Box 119 \ 3 scan0105 | |
| High-speed test results on the cooling benefits of front and rear shutters versus a louvred bonnet. | 19th Sep 1927 | Box 119 \ 3 scan0106 | |
| Arrangement of a car to test a louvred bonnet against a closed bonnet. | 20th Sep 1927 | Box 119 \ 3 scan0107 | |
| Scuttle ventilation tests on the 10-EX model, comparing the effects of louvered and plain bonnets on cabin temperature. | 2nd Jan 1928 | Box 119 \ 3 scan0108 | |
| Insufficient cooling on the Phantom II model in hot climates and the efficiency of its bonnet shutters. | 1st Sep 1930 | Box 119 \ 3 scan0109 | |
| Reconsideration of front versus rear shutters for the Phantom II cooling system to aid petrol tank cooling. | 3rd Sep 1930 | Box 119 \ 3 scan0110 | |
| Decision to delete the back bonnet shutters and the painting process for the remaining ones. | 9th Jul 1927 | Box 119 \ 3 scan0111 | |
| Confirming design changes for the 40/50 HP bonnets regarding shutters and louvres. | 22th Jul 1927 | Box 119 \ 3 scan0112 | |
| Removal of rear bonnet shutters and its effect on cooling efficiency. | 30th Jun 1927 | Box 119 \ 3 scan0113 | |
| Various modifications for increased engine cooling on 25 HP and 45 HP models. | 4th Jul 1930 | Box 119 \ 3 scan0114 | |
| Impracticality of current bonnet shutters and suggesting a more user-friendly design. | 30th Jul 1930 | Box 119 \ 3 scan0115 | |
| Overheating issues and proposed modifications for the Phantom II model. | 4th Sep 1930 | Box 119 \ 3 scan0116 | |
| Ongoing tests for Phantom II overheating by investigating the reduction or modification of undershields. | 8th Sep 1930 | Box 119 \ 3 scan0117 | |
| Modifications and improvements to the vehicle's cooling system, including shutters, radiator, and louvres. | 1st Oct 1930 | Box 119 \ 3 scan0118 | |
| Merits of square tube radiators, overflow valves, and bonnet vents. | 14th Oct 1930 | Box 119 \ 3 scan0119 | |
| Benefits of square versus round radiator tubes and updating bonnet vent designs. | 27th Oct 1930 | Box 119 \ 3 scan0120 | |
| Performance of square radiator tubes compared to round tubes and the design of a bonnet for ventilation. | 30th Oct 1930 | Box 119 \ 3 scan0121 | |
| Requesting the manufacture of a new ventilated bonnet with three shutters for testing on a 40/50 model. | 13th Apr 1931 | Box 119 \ 3 scan0122 | |
| Appearance and fitting of new 'flip-flap' bonnet ventilators for show cars. | 25th Jun 1931 | Box 119 \ 3 scan0123 | |
| Consultation on a reply regarding bonnet ventilators. | 26th Jun 1931 | Box 119 \ 3 scan0124 | |
| Criticisms and requested modifications for 'Flip-Flap' type bonnet ventilators. | 26th Jun 1931 | Box 119 \ 3 scan0125 | |
| Design improvements for flip-flap bonnet shutters, covering operation and construction. | 26th Jun 1931 | Box 119 \ 3 scan0126 | |
| Bonnet materials, riveting specifications, and concerns about rust prevention. | 26th Jun 1931 | Box 119 \ 3 scan0127 | |
| Operational and constructional modifications for bonnet shutters. | 30th Jun 1931 | Box 119 \ 3 scan0128 | |
| The schedule for converting bonnets to use modified flip-flap shutters for the Show chassis. | 1st Jul 1931 | Box 119 \ 3 scan0129 | |
| Alternative methods for finishing the edges of bonnet shutters. | 2nd Jul 1931 | Box 119 \ 3 scan0130 | |
| Bringing a car fitted with modified flip flap bonnet ventilators for an inspection. | 3rd Jul 1931 | Box 119 \ 3 scan0131 | |
| Bonnet ventilators, arranging a car inspection in London with modified flipflap shutters. | 4th Jul 1931 | Box 119 \ 3 scan0132 | |
| Approval and standardisation of modified flap bonnet ventilators for the N.2. series and Show cars. | 6th Jul 1931 | Box 119 \ 3 scan0133 | |
| Bonnet ventilators and overheating concerns related to different radiator tube types. | 7th Jul 1931 | Box 119 \ 3 scan0134 | |
| Two different aluminium bonnet designs, one with flip-flap shutters and another louvred version, with suggestions for improving the latter. | 7th Jul 1931 | Box 119 \ 3 scan0135 | |
| Fitting louvres instead of bonnet ventilators to Continental chassis for the Olympia and Paris Shows. | 7th Jul 1931 | Box 119 \ 3 scan0136 | |
| Future standards for bonnet ventilators, specifically the transition from sliding to flap type shutters. | 8th Jul 1931 | Box 119 \ 3 scan0137 | |
| Use of hard versus soft aluminium for louvred bonnets and the necessity of a stiffening frame. | 10th Jul 1931 | Box 119 \ 3 scan0138 | |
| Standardisation sheet regarding the design alteration of flip flap type bonnet ventilators. | 14th Jul 1931 | Box 119 \ 3 scan0139 | |
| Alternative designs and material choices for rivetless car bonnets. | 15th Jul 1931 | Box 119 \ 3 scan0140 | |
| Potential overheating in Left-hand drive Phantom II cars for America and proposing the incorporation of 'flap' type shutters. | 20th Jul 1931 | Box 119 \ 3 scan0141 | |
| Development of bonnets without rivets and issues with louvred designs. | 20th Aug 1931 | Box 119 \ 3 scan0142 | |
| Design and development of rivetless aluminium bonnets, noting pressure from the sales department. | 22th Aug 1931 | Box 119 \ 3 scan0143 | |
| Requesting a blueprint to fit extracting louvres in the scuttle of a 25HP Special Touring Saloon. | 22th Aug 1931 | Box 119 \ 3 scan0144 | |
| Design of a louvered bonnet and scuttle for a 25HP 'U' Series Special Touring Saloon. | 2nd Sep 1931 | Box 119 \ 3 scan0145 | |
| Left-handed Phantom I models for America, specifically following up on a query about bonnets. | 4th Sep 1931 | Box 119 \ 3 scan0146 | |
| The design, testing, and implementation of rivetless bonnets. | 4th Sep 1931 | Box 119 \ 3 scan0147 | |
| Use of bonnet shutters on left-hand drive P.2 cars for the American market. | 7th Sep 1931 | Box 119 \ 3 scan0148 | |
| Information about introducing 'flip-flap' shutters to the L.H.Phantom II chassis for American cars. | 8th Sep 1931 | Box 119 \ 3 scan0149 | |
| Request for a photograph of flip-flap shutters on a bonnet for an L.H.Phantom II car destined for America. | 21th Sep 1931 | Box 119 \ 3 scan0150 | |
| Improving engine cooling by comparing the effectiveness of bonnet shutters versus louvres. | 1st Oct 1931 | Box 119 \ 3 scan0151 | |
| Reminder note from Sg. to Hs. regarding a requested photograph of flip-flap shutters for a L.H.Phantom II Car for America. | 2nd Oct 1931 | Box 119 \ 3 scan0152 | |
| Photographs of bonnets with flip-flap shutters and without rivets for Left-Hand Phantom II cars. | 3rd Oct 1931 | Box 119 \ 3 scan0153 | |
| Photograph showing a close-up of a car's bonnet, side lamp, and scuttle. | 3rd Oct 1931 | Box 119 \ 3 scan0154 | |
| Photograph showing a side view of a car's bonnet and scuttle. | 5th Oct 1931 | Box 119 \ 3 scan0155 | |
| Cost and an alternative to adding flip-flop shutters to the bonnet. | 5th Oct 1931 | Box 119 \ 3 scan0156 | |
| Deferring action on increasing the number of flip-flap shutters. | 12th Oct 1931 | Box 119 \ 3 scan0157 | |
| Proposal to modify the flip flap shutters on the rivetless bonnet for the 22-EX model. | 19th Oct 1931 | Box 119 \ 3 scan0158 | |
| Aesthetic improvements to bonnet shutters by widening the gap and rounding the edges, and requesting a sample. | 20th Oct 1931 | Box 119 \ 3 scan0159 | |
| Clearance of bonnet shutters and the impact of paint thickness. | 21th Oct 1931 | Box 119 \ 3 scan0160 | |
| Providing the contact details for W. H. Colt Ltd. and requesting an inspection of their ventilators. | 21th Oct 1931 | Box 119 \ 3 scan0161 | |
| Particulars of Colt K.K. patent ventilators and other engine components. | 24th Oct 1931 | Box 119 \ 3 scan0162 | |
| Modifications to bonnet shutters, specifically increasing the radius and gap for a continental touring saloon. | 26th Oct 1931 | Box 119 \ 3 scan0163 | |
| Forwarding an original letter from W. H. Colt, Ltd. concerning ventilators. | 30th Oct 1931 | Box 119 \ 3 scan0164 | |
| Letter from W. H. Colt Ltd. discussing engine cooling, heat build-up, and potential fan modifications. | 28th Oct 1931 | Box 119 \ 3 scan0165 | |
| Engine and car interior ventilation methods, including proposed tests and commercial negotiations for related devices. | 28th Oct 1931 | Box 119 \ 3 scan0166 | |
| The final page of a typed letter from W. H. Colt Ltd. concerning exclusive rights. | 18th Aug 1931 | Box 119 \ 3 scan0167 | |
| Product sheet for a Type B.S. Vehicle Roof Ventilator (Air Extractor). | 18th Aug 1931 | Box 119 \ 3 scan0168 | |
| Advertisement sheet for a patented Scuttle (H.O.) type combined air extractor and wind scoop from Colt Ventilation Ltd. | 18th Aug 1931 | Box 119 \ 3 scan0169 | |
| Blueprint showing a louvered vent and a side view of a domed component, possibly a lamp. | 18th Aug 1931 | Box 119 \ 3 scan0170 | |
| Multi-view engineering drawing of a piston-like component with internal fins. | 18th Aug 1931 | Box 119 \ 3 scan0171 | |
| Technical drawing of a Scuttle Ventilator (H.O.). | 18th Aug 1931 | Box 119 \ 3 scan0172 | |
| Blueprint showing two designs for car bonnet louvres. | 4th Nov 1931 | Box 119 \ 3 scan0173 | |
| Response to W.H. Colt, Ltd. regarding proposals for bonnet ventilators and other car components. | 4th Nov 1931 | Box 119 \ 3 scan0174 | |
| Letter from W. H. Colt, Ltd. regarding the design of a 'K.K' ventilator for an engine bonnet. | 7th Nov 1931 | Box 119 \ 3 scan0175 | |
| Letter regarding the performance of a device and the sourcing of samples for ventilators, fans, and radiator contra-shields. | 7th Nov 1931 | Box 119 \ 3 scan0176 | |
| Sketch showing the placement and dimensions of a 'Colt K extractor' ventilator on a car bonnet. | 10th Nov 1931 | Box 119 \ 3 scan0177 | |
| Letter to W.H. Colt Ltd. confirming an order for a pair of aluminium bonnet ventilators for testing. | 10th Nov 1931 | Box 119 \ 3 scan0178 | |
| Letter from W. H. Colt, Ltd. regarding the provision of a pair of aluminium bonnet ventilators for testing. | 11th Nov 1931 | Box 119 \ 3 scan0179 | |
| Letter from W. H. Colt Ltd regarding the testing of bonnet ventilators made from aluminium and brass. | 17th Nov 1931 | Box 119 \ 3 scan0180 | |
| Cover letter forwarding an inquiry from W.H. Colt, Ltd. concerning bonnet ventilators. | 19th Nov 1931 | Box 119 \ 3 scan0181 | |
| Letter from W. H. Colt Ltd. discussing the inspection and potential improvement of an extraction device, oil sump, and fan. | 12th Nov 1931 | Box 119 \ 3 scan0182 | |
| Request for the minimum and maximum revolutions per minute for two nominal fan types for test verification. | 8th Jul 1931 | Box 119 \ 3 scan0183 | |
| Standardisation of pivoted flip-flap type bonnet ventilators. | 8th Jul 1931 | Box 119 \ 3 scan0184 | |
| Standardisation form for a new part to be fitted on the N.2. Series chassis, including cost details. | 12th Jul 1921 | Box 119 \ 3 scan0185 | |
| Letter from W. H. Colt Ltd. discussing bonnet ventilators and a new fan design with automatic blade-pitch adjustment. | 25th Nov 1931 | Box 119 \ 3 scan0186 | |
| Page 2 of a letter discussing fan performance charts, comparing a standard fan to one with adjustable blades. | 25th Nov 1931 | Box 119 \ 3 scan0187 | |
| Performance graph for a Colt K.K. Fan showing HP and Air Volume curves. | 25th Nov 1931 | Box 119 \ 3 scan0188 | |
| Hand-drawn graph showing Horsepower and Air Volume characteristics for Fixed Blades. | 30th Nov 1931 | Box 119 \ 3 scan0189 | |
| Letter to W. H. Colt Ltd. regarding the loan of a standard Phantom II type fan. | 30th Nov 1931 | Box 119 \ 3 scan0190 | |
| Standardisation of flip flap type bonnet ventilators similar to the Phantom model to overcome overheating. | 5th Oct 1931 | Box 119 \ 3 scan0191 | |
| Introduction of a new standardized part for a chassis. | 27th Dec 1920 | Box 119 \ 3 scan0192 | |
| Letter from W.H. Colt Ltd. requesting progress on experiments with an Aluminium Bonnet Vent. | 19th Dec 1931 | Box 119 \ 3 scan0193 | |
| Letter from W. H. Colt Ltd. concerning tests on a self-adjusting fan and bonnet ventilation device. | 3rd Feb 1932 | Box 119 \ 3 scan0194 | |
| Page two of a letter from Colt Ventilation Ltd discussing a fan device and seeking approval. | 5th Feb 1932 | Box 119 \ 3 scan0195 | |
| Letter to W.H. Colt Ltd. regarding inconsistent test results for a bonnet ventilation device due to windy conditions. | 5th Feb 1932 | Box 119 \ 3 scan0196 | |
| Letter to W.H. Colt Ltd. regarding the disappointing test results of their bonnet ventilators. | 10th Feb 1932 | Box 119 \ 3 scan0197 | |
| Graphs of tests recording under-bonnet pressure versus road speed for different ventilation configurations. | 1st Feb 1932 | Box 119 \ 3 scan0198 | |
| Letter from W. H. Colt Ltd. regarding preliminary test results for a bonnet device and alternative fan systems. | 15th Feb 1932 | Box 119 \ 3 scan0199 | |
| Letter to W.H. Colt Ltd. regarding the unsatisfactory results of tests on a bonnet ventilator device. | 15th Feb 1932 | Box 119 \ 3 scan0200 | |
| Thermostatically operated bonnet shutters, referencing a picture from a Lincoln. | 24th Apr 1934 | Box 119 \ 3 scan0201 | |
| Letter from Ford Motor Company regarding oil consumption and thermostatically operated bonnet side shutters on Lincoln cars. | 27th Apr 1934 | Box 119 \ 3 scan0202 | |
| Description of the operation of thermostatic radiator shutters and hood ventilators. | 27th Apr 1934 | Box 119 \ 3 scan0203 | |
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