| Description | Date | Identifier | |
| Request for a sample of a 12-volt Sparton S.O.S. Deluxe Horn for testing as a less raucous alternative to the Klaxon horn. | 6th Mar 1929 | Box 49 \ 5 Scan126 | |
| Instructions and description for a Sparton SCS De Luxe Bugle Type Horn. | 31th Mar 1929 | Box 49 \ 5 Scan127 | |
| Instructions detailing the electrical and acoustic properties of a horn. | 8th Dec 1924 | Box 49 \ 5 Scan128 | |
| Instruction and service reference booklet for a Sparton horn, including the guaranty. | 1st Apr 1926 | Box 49 \ 5 Scan129 | |
| Care and maintenance instructions for Sparton Motorhorns, with a cutaway diagram. | 1st Jan 1925 | Box 49 \ 5 Scan130 | |
| Installation instructions and important information for the Sparton SOS horn. | 1st Jan 1925 | Box 49 \ 5 Scan131 | |
| Fitting of an electro buzzer versus a low note bulb horn for aesthetic and practical reasons. | 14th Mar 1929 | Box 49 \ 5 Scan132 | |
| Sending a 'Sparton Bugle' back to the makers and refusing a 'Chime' version. | 22th Mar 1929 | Box 49 \ 5 Scan133 | |
| Letter regarding Chassis Alteration No.7, discussing the Sparton SOS deLuxe horn versus the Robt. Bosch model and justifying its placement on the cylinder head. | 28th Mar 1929 | Box 49 \ 5 Scan134 | |
| Query regarding the purchase of a Sparton S.O.S. De Luxe Horn retained for testing purposes. | 23th May 1929 | Box 49 \ 5 Scan135 | |
| Follow-up memo requesting a reply regarding the Sparton S.O.S. De Luxe Horn. | 28th May 1929 | Box 49 \ 5 Scan136 | |
| Return of an unsatisfactory Sparton S.O.S. De Luxe Horn. | 3rd Jun 1929 | Box 49 \ 5 Scan137 | |
| Test report on two makes of vibration type electric horns which were found to be unsatisfactory. | 16th Jul 1929 | Box 49 \ 5 Scan138 | |
| Comparison between a post-war Bosch Magneto and a Watford Magneto, with a list of complaints about the latter. | 1st Aug 1920 | Box 49 \ 5 Scan139 | |
| Letter to North & Sons Ltd. comparing their 'Watford' magneto unfavourably with the German Bosch magneto. | 1st Sep 1920 | Box 49 \ 5 Scan140 | |
| Comparison between Bosch and Watford magnetos, outlining the superior qualities of the Bosch machine. | 10th Dec 1920 | Box 49 \ 5 Scan141 | |
| Letter from North & Sons Ltd. discussing the requirements for a new magneto, including spark gaps and armature design. | 6th Sep 1920 | Box 49 \ 5 Scan142 | |
| Page 2 of a letter from North & Sons Ltd. regarding a wider machine and potential modifications. | 9th Sep 1920 | Box 49 \ 5 Scan143 | |
| Correspondence regarding weak points in a magneto from Messrs. Norths and the promise of an improvement. | 9th Sep 1920 | Box 49 \ 5 Scan144 | |
| Letter to a supplier discussing the development of a new machine, emphasising the time factor and arranging a meeting. | 7th Sep 1920 | Box 49 \ 5 Scan145 | |
| Correspondence from North & Sons Ltd. regarding the development of a new model magneto with a larger armature. | 10th Sep 1920 | Box 49 \ 5 Scan146 | |
| Letter from North & Sons Ltd. regarding the testing and supply of E.O.6 magnetos. | 12th Jan 1921 | Box 49 \ 5 Scan147 | |
| Letter to Messrs. North & Sons Ltd. regarding tests and required improvements for magnetos on R.R. Chassis. | 9th Mar 1921 | Box 49 \ 5 Scan148 | |
| Letter from North & Sons, Ltd. regarding the design and testing of E.O.6 magnetos. | 11th Mar 1921 | Box 49 \ 5 Scan149 | |
| Letter from North & Sons, Ltd. arranging the inspection of a sample machine. | 11th Aug 1941 | Box 49 \ 5 Scan150 | |
| Stating a preference to use German Robert Bosch, American Bosch, and Watford magnetos over other suppliers. | 24th Mar 1921 | Box 49 \ 5 Scan151 | |
| Forwarding a letter regarding the large armature type magneto from Watford Magnetos and a recent works visit. | 22th Mar 1921 | Box 49 \ 5 Scan152 | |
| Letter from North & Sons, Ltd. regarding the progress and sample submission of a Large Armature Type Magneto. | 21th Mar 1921 | Box 49 \ 5 Scan153 | |
| Timing, weight, and performance issues of Watford magnetos in comparison to Bosch and Conner models. | 8th Apr 1921 | Box 49 \ 5 Scan154 | |
| Letter from North & Sons, Ltd. regarding progress on a machine and arranging a meeting. | 21th Apr 1921 | Box 49 \ 5 Scan155 | |
| The second page of a letter regarding sending a copy to an alternative address to avoid postal delays. | 21th Apr 1921 | Box 49 \ 5 Scan156 | |
| Magneto performance issues, specifically the influence of Lodge spark plugs on misfiring and the capabilities of Watford magnetos at slow speeds. | 25th Apr 1921 | Box 49 \ 5 Scan157 | |
| Visit to magneto supplier Messrs. North regarding the exchange of E.6 magnetos and details of a new larger armature magneto design. | 6th May 1921 | Box 49 \ 5 Scan158 | |
| Magneto requirements for the 40/50 engine, comparing different types and analyzing spark plug performance. | 5th May 1921 | Box 49 \ 5 Scan159 | |
| Tests of ignition coils with varying numbers of secondary turns for magnetos. | 5th May 1921 | Box 49 \ 5 Scan160 | |
| Supply and exchange of Watford magnetos with North & Sons Ltd. | 18th May 1921 | Box 49 \ 5 Scan161 | |
| Correspondence regarding a sample E.L.O.6 magneto from North & Sons Ltd for testing. | 26th Apr 1922 | Box 49 \ 5 Scan162 | |
| Design, performance, and testing of a Watford magneto. | 19th Jul 1922 | Box 49 \ 5 Scan163 | |
| Specifications for an ignition distributor, platinum point gap, and contact breaker timing. | 19th Jul 1922 | Box 49 \ 5 Scan164 | |
| Test report page detailing an endurance test, primary volt-speed curve, and primary ampere-speed curve for a component. | 19th Jul 1922 | Box 49 \ 5 Scan165 | |
| Test report page detailing circuit tests, RPM tests, measurements, and handwritten notes on an advance and retard mechanism. | 19th Jul 1922 | Box 49 \ 5 Scan166 | |
| Test report on high and low speed sparking characteristics, and contact breaker performance. | 19th Jul 1922 | Box 49 \ 5 Scan167 | |
| List of electrical and mechanical specifications including resistance, current, point gaps and contact breaker timing. | 8th Mar 1921 | Box 49 \ 5 Scan168 | |
| Specifications for platinum point gap, contact breaker timing, and armature core flux. | 8th Mar 1921 | Box 49 \ 5 Scan169 | |
| The comparative tests of three magnetos: U.S.A. BOSCH ZR.6 ED.19, WATFORD EO6c, and WATFORD ELO.6. | 31th Jul 1922 | Box 49 \ 5 Scan170 | |
| Report page comparing the specifications and test results of various Bosch and Watford magnetos. | 31th Jul 1922 | Box 49 \ 5 Scan171 | |
| Comparison and specification report on various magneto models, including the ELO.6, EO6, and ZR.6. | 31th Jul 1922 | Box 49 \ 5 Scan172 | |
| Magneto distributor dimensions, platinum point gaps, and contact breaker timing. | 31th Jul 1922 | Box 49 \ 5 Scan173 | |
| Test report on magneto timing, gaps, and endurance for various models. | 31th Jul 1922 | Box 49 \ 5 Scan174 | |
| Test report on magneto performance, detailing wear, tracking, and electrical test results. | 31th Jul 1922 | Box 49 \ 5 Scan175 | |
| Comparative tests on various magnetos, including spark gap and utility tests. | 31th Jul 1922 | Box 49 \ 5 Scan176 | |
| Test procedure for establishing the comparative high and low speed sparking characteristics of a ZR.6 machine. | 31th Jul 1922 | Box 49 \ 5 Scan177 | |
| Magneto timing ranges and high-speed sparking characteristics for various models. | 31th Jul 1922 | Box 49 \ 5 Scan178 | |
| Magneto spark gap performance at various speeds and timing settings for E.O.6c and ELO.6 machines. | 31th Jul 1922 | Box 49 \ 5 Scan179 | |
| The low-speed sparking characteristics of various magnetos and drive types. | 31th Jul 1922 | Box 49 \ 5 Scan180 | |
| Test results page comparing primary/secondary resistances and milli-amperes for various magnetos. | 31th Jul 1922 | Box 49 \ 5 Scan181 | |
| Performance comparison graph of electrical components, plotting Amperes and Volts against RPM. | 2nd Aug 1939 | Box 49 \ 5 Scan182 | |
| Faint typewritten internal document with a purple date stamp. | 2nd Aug 1939 | Box 49 \ 5 Scan183 | |
| Confirming an arrangement to fit a larger armature Watford magneto to a 40/50 chassis by creating a suitable base. | 11th Dec 1922 | Box 49 \ 5 Scan184 | |
| Test report on a Watford Magneto with a larger armature for improved slow running. | 28th Mar 1923 | Box 49 \ 5 Scan185 | |
| Return of a tested Watford Magneto Type E.L.O.6 to its owner, Messrs. North & Sons. | 28th Mar 1923 | Box 49 \ 5 Scan186 | |
| Returning a tested Watford type E.L.O.6 Magneto to Messrs. North & Sons Ltd. | 29th Mar 1923 | Box 49 \ 5 Scan187 | |
| Announcement from Trojan Commercial Corporation regarding the Fan Flame Spark Plug. | 25th Nov 1920 | Box 49 \ 5 Scan188 | |
| Letter from the Trojan Commercial Corporation detailing pricing, packaging, and agency terms for their plugs. | 25th Nov 1920 | Box 49 \ 5 Scan189 | |
| Advertising leaflet for 'Fan Flame' spark plugs, detailing available sizes and prices. | 15th Sep 1919 | Box 49 \ 5 Scan190 | |
| Promotional document featuring customer testimonials for 'FAN FLAME SPARK PLUGS'. | 15th Sep 1919 | Box 49 \ 5 Scan191 | |
| Letter to Trojan Commercial Corporation requesting a sample of their Fan Flame Sparking Plugs for examination. | 25th Nov 1920 | Box 49 \ 5 Scan192 | |
| Letter from the Trojan Commercial Corporation regarding a sample set of 'Fan Flame' spark plugs sent for testing. | 8th Dec 1920 | Box 49 \ 5 Scan193 | |
| Follow-up letter from Trojan Commercial Corporation regarding 'Fan Flame' spark plugs sent for testing. | 8th Feb 1921 | Box 49 \ 5 Scan194 | |
| Invoice from Trojan Commercial Corporation for the supply of 12 standard metric fan flame spark plugs. | 8th Dec 1920 | Box 49 \ 5 Scan195 | |
| Telegram from Brooklyn, NY, with a coded message regarding 'Fanflame Sparkplugs'. | 25th Feb 1921 | Box 49 \ 5 Scan196 | |
| Methodology for testing various makes of sparking plugs. | 9th Feb 1921 | Box 49 \ 5 Scan197 | |
| Test report comparing the performance of various spark plugs. | 9th Feb 1921 | Box 49 \ 5 Scan198 | |
| Report comparing and recommending spark plugs, specifically Mercury, Champion, and Bethlehem brands. | 9th Feb 1921 | Box 49 \ 5 Scan199 | |
| Letter from Trojan Commercial Corporation following up on an offer for the exclusive agency of 'Fan Flame' spark plugs in England. | 3rd Mar 1921 | Box 49 \ 5 Scan200 | |
| Translation of a coded cable message using the A.B.C. 5th Edition code. | 24th Feb 1921 | Box 49 \ 5 Scan201 | |
| Instructions for a Bosch Trembler Ignition Coil GZ4. | 23th Mar 1921 | Box 49 \ 5 Scan202 | |
| Instructions detailing the construction of a coil and condenser assembly. | 24th Jan 1919 | Box 49 \ 5 Scan203 | |
| Instructions for the operation of a switching mechanism and its components. | 24th Jan 1919 | Box 49 \ 5 Scan204 | |
| Inspection notes on a vehicle's ignition system, detailing coil and magneto conditions. | 24th Jan 1919 | Box 49 \ 5 Scan205 | |
| Wiring diagram for a Bosch GZA Trembler Ignition Coil. | 23th Mar 1921 | Box 49 \ 5 Scan206 | |
| Production tests for a motor and reduction gear, detailing the light test procedure. | 28th Aug 1919 | Box 49 \ 5 Scan207 | |
| Pencil sketch of a steering wheel mechanism, possibly for a horn or self-cancelling indicator, incorporating springs and electrical contacts. | 1st Dec 1920 | Box 49 \ 5 Scan208 | |
| Instructions for creating Goshawk 11 combustion space models and details on piston modifications for Mr. Royce's inspection. | 1st Dec 1920 | Box 49 \ 5 Scan209 | |
| Request to obtain an R. Bosch TA.12 ignition coil with condenser for examination. | 26th Nov 1929 | Box 49 \ 5 Scan210 | |
| Letter from American Bosch Magneto Corporation regarding sample magnetos and ignition system components. | 12th Jan 1921 | Box 49 \ 5 Scan211 | |
| Letter from Rolls-Royce of America concerning changes to the American Bosch Magneto DUZ-6 model. | 4th Mar 1921 | Box 49 \ 5 Scan212 | |
| Forwarding a copy of a letter from America concerning American Bosch Battery Ignition. | 13th Apr 1921 | Box 49 \ 5 Scan213 | |
| Letter clarifying the material composition of a contact breaker for an American Bosch Battery Ignition system. | 25th Mar 1921 | Box 49 \ 5 Scan214 | |
| Covering letter for a preliminary report on a U.S.A. Bosch Type D.U.Z.6 Magneto. | 15th Apr 1921 | Box 49 \ 5 Scan215 | |
| Preliminary report on the U.S.A. Bosch Magneto D.U.Z.6, comparing it to the Z.R.6 model. | 30th Mar 1921 | Box 49 \ 5 Scan216 | |
| Disassembled U.S.A. Bosch Type ZR.6 magneto and a request for another for testing, plus parts for other magnetos. | 15th Apr 1921 | Box 49 \ 5 Scan217 | |
| Form for recording details of magneto design and performance for a U.S.A. Bosch D.U.Z.6. | 20th Apr 1921 | Box 49 \ 5 Scan218 | |
| Specification sheet for ignition system components and timing. | 10th Dec 1920 | Box 49 \ 5 Scan219 | |
| Endurance test results showing a seized distributor gear bearing, with primary volt-speed and ampere-speed curve data. | 10th Dec 1926 | Box 49 \ 5 Scan220 | |
| Page of test results including circuit tests, RPM test, measurements, and handwritten notes on timing advance and retard. | 10th Dec 1920 | Box 49 \ 5 Scan221 | |
| High and low-speed sparking characteristics and contact breaker performance. | 10th Dec 1920 | Box 49 \ 5 Scan222 | |
| Technical data sheet detailing resistance values, point gaps, and contact breaker timings. | 10th Dec 1920 | Box 49 \ 5 Scan223 | |
| Specifications for platinum point gap, contact breaker timing, and armature core flux. | 8th Mar 1921 | Box 49 \ 5 Scan224 | |
| Letter from the American branch requesting an order for spare magneto parts and fittings. | 2nd May 1921 | Box 49 \ 5 Scan225 | |
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