| Description | Date | Identifier | |
| Continuation sheet from North & Sons Ltd concerning modifications to a driving disc. | 22th Dec 1926 | Box 43 \ 4 Scan097 | |
| Drawing of an automatic advance to suit a Simm's coupling with 20 teeth. | 22th Dec 1926 | Box 43 \ 4 Scan098 | |
| Proposal from Messrs. North & Sons for a Watford Aero Magneto's automatic advance mechanism. | 30th Nov 1927 | Box 43 \ 4 Scan099 | |
| Letter to North & Sons Ltd. discussing requirements for magnetos on 12-cylinder aero engines, specifically regarding automatic advance mechanisms. | 1st Dec 1927 | Box 43 \ 4 Scan100 | |
| Letter asking for a lighter and smaller magneto alternative to the dual magneto drive. | 3rd Dec 1927 | Box 43 \ 4 Scan101 | |
| Letter from North & Sons, Ltd. regarding modifications and testing of aero magnetos. | 3rd Dec 1927 | Box 43 \ 4 Scan102 | |
| Production of a Watford 12-cylinder aero magneto and potential size reduction. | 6th Dec 1927 | Box 43 \ 4 Scan103 | |
| Letter to North & Sons Ltd. regarding the return of four IS12 aero magnetos for comparative testing. | 8th Dec 1927 | Box 43 \ 4 Scan104 | |
| Telephone message about the specifications of a new Watford aero engine magneto. | 22th Dec 1927 | Box 43 \ 4 Scan105 | |
| Electrical experimental record sheet for a Watford IS 8-8 aero magneto, number 83104. | 19th Apr 1926 | Box 43 \ 4 Scan106 | |
| Letter from North & Sons, Ltd. concerning the return and testing of aero magnetos. | 22th Dec 1927 | Box 43 \ 4 Scan107 | |
| Continuation sheet from North & Sons Ltd discussing experiments with an inductor type of machine. | 12th Jan 1928 | Box 43 \ 4 Scan108 | |
| Table detailing the location and status of various Watford Aero Magnetos. | 12th Jan 1928 | Box 43 \ 4 Scan109 | |
| Letter to Messrs. North & Sons Ltd. clarifying specifications for aero and chassis magnetos, specifically regarding the point at break and make variations. | 4th Jan 1927 | Box 43 \ 4 Scan110 | |
| Suggesting to send Bosch and Scintilla magneto samples and test results to Watford to aid English manufacturers. | 21th Jan 1928 | Box 43 \ 4 Scan111 | |
| Testing and inspection of various aero magnetos to assist English manufacturers. | 2nd Feb 1928 | Box 43 \ 4 Scan112 | |
| Suitability of a true inductor type aero magneto, as represented by Watford and R. Bosch of Germany. | 7th Feb 1928 | Box 43 \ 4 Scan113 | |
| Letter from North & Sons, Ltd. concerning the supply of experimental aero engine magnetos and the need for an Air Ministry contract. | 13th Feb 1928 | Box 43 \ 4 Scan114 | |
| Letter from North & Sons, Ltd. to E. Fowler Clark Esq. regarding a potential contract for magnetos. | 13th Feb 1928 | Box 43 \ 4 Scan115 | |
| From EFC to Rg regarding a quote for Watford aero engine magnetos. | 1st Feb 1928 | Box 43 \ 4 Scan116 | |
| The moment of inertia for a lightened B.T.H. aero magneto rotor. | 17th Apr 1928 | Box 43 \ 4 Scan117 | |
| The testing, issues, and modifications of Watford IS.12 aero magnetos. | 7th May 1928 | Box 43 \ 4 Scan118 | |
| Letter to Messrs. North & Sons Ltd. regarding the supply of Watford 12-cylinder aero magnetos with an updated specification. | 7th May 1928 | Box 43 \ 4 Scan119 | |
| Letter from supplier North & Sons regarding a delay and availability of 12-cylinder magnetos. | 9th May 1928 | Box 43 \ 4 Scan120 | |
| Requesting to place an order for a pair of Watford Aero Magnetos. | 10th May 1928 | Box 43 \ 4 Scan121 | |
| Procurement and modification of magnetos for 'F' Type engines. | 15th May 1928 | Box 43 \ 4 Scan122 | |
| Acquisition of two Watford 12-cylinder magnetos for experimental use, waiving the A.I.D. inspection. | 25th May 1928 | Box 43 \ 4 Scan123 | |
| Confirming the cost of two special Watford aero magnetos. | 6th Jun 1928 | Box 43 \ 4 Scan124 | |
| Covering letter regarding the arrival of two 12 Cylinder Magnetos ordered from Messrs. North & Sons. | 12th Jul 1928 | Box 43 \ 4 Scan125 | |
| Letter from North & Sons, Limited regarding the completion and dispatch of two Watford 12 Cylinder Magnetos. | 9th Jul 1928 | Box 43 \ 4 Scan126 | |
| Wording of labels and instructions for 12-cylinder magnetos. | 19th Jul 1928 | Box 43 \ 4 Scan127 | |
| Form recording the design and performance details of a magneto. | 19th Jul 1928 | Box 43 \ 4 Scan128 | |
| Specifications for primary point gap, contact breaker timing, and automatic advance characteristics. | 19th Jul 1928 | Box 43 \ 4 Scan129 | |
| Test results for Endurance, Short circuit, and Open circuit, including a volt-speed curve. | 19th Jul 1928 | Box 43 \ 4 Scan130 | |
| Test report detailing primary ampere-speed curve data and spark characteristics at various speeds. | 19th Jul 1928 | Box 43 \ 4 Scan131 | |
| Test results for contact breaker timing and primary point gap measurements. | 19th Jul 1928 | Box 43 \ 4 Scan132 | |
| Continuation page of a report regarding the silence of operation and tangential force. | 20th Jul 1928 | Box 43 \ 4 Scan133 | |
| Bench test report on modified 30° range Watford IS 12 aero magnetos, comparing their performance to B.T.H. magnetos. | 20th Jul 1928 | Box 43 \ 4 Scan134 | |
| Report comparing the performance of a Watford magneto against a B.T.H. magneto. | 1st Dec 1924 | Box 43 \ 4 Scan135 | |
| Instructions on magneto wire windings and contact breaker timing for improved performance. | 8th Dec 1924 | Box 43 \ 4 Scan136 | |
| Comparison of screening methods for B.T.H magnetos, favouring the design by Messrs Norths to prevent wireless interference. | 8th Dec 1924 | Box 43 \ 4 Scan137 | |
| Instructions comparing a magneto distributor block's design to a B.T.H. model and its expected performance. | 8th Dec 1924 | Box 43 \ 4 Scan138 | |
| Contact breaker timing specifications for Watford IS.12 Aero Magnetos with latest modifications. | 14th Aug 1928 | Box 43 \ 4 Scan139 | |
| Performance and high price of newly received Watford 12-cylinder aero magnetos. | 6th Sep 1928 | Box 43 \ 4 Scan140 | |
| Fitting a pair of Watford IS12 aero magnetos to a development engine for testing. | 2nd Sep 1928 | Box 43 \ 4 Scan141 | |
| The performance and improvements of the latest Watford IS12 aero magnetos, with a comparison to B.T.H. models. | 10th Sep 1928 | Box 43 \ 4 Scan142 | |
| Comparison of a new magneto's performance and screening method against existing B.T.H. types. | 15th Oct 1928 | Box 43 \ 4 Scan143 | |
| Requesting feedback on Watford Type IS12 magnetos tested on a development light alloy engine T49. | 15th Oct 1928 | Box 43 \ 4 Scan144 | |
| Quotation from Messrs. North & Sons Ltd. for 'R' Engine Magnetos, including weight, price, and delivery details. | 19th Jan 1929 | Box 43 \ 4 Scan145 | |
| Fitting Watford magnetos to an F engine for a D.H.9A aircraft. | 29th Jan 1929 | Box 43 \ 4 Scan146 | |
| The performance of Watford magnetos on F. engines after a 120-hour test run. | 23th Feb 1929 | Box 43 \ 4 Scan147 | |
| The satisfactory condition of Watford Aero Magnetos type I.S.12 following a 120-hour test. | 1st Feb 1929 | Box 43 \ 4 Scan148 | |
| Electrical experimental record sheet for a Watford aero magneto type IS12 NO 83132. | 19th Apr 1926 | Box 43 \ 4 Scan149 | |
| Electrical experimental record sheet for a Watford aero magneto type IS12 N083133. | 19th Apr 1926 | Box 43 \ 4 Scan150 | |
| Electrical experimental record sheet for a Watford aero magneto, type IS12, No. 83119. | 19th Apr 1926 | Box 43 \ 4 Scan151 | |
| Electrical experimental record sheet for a Watford aero magneto type TS12. | 19th Apr 1926 | Box 43 \ 4 Scan152 | |
| The return of a pair of Watford I.S.12 magnetos to the makers for reconditioning and testing. | 21th Feb 1929 | Box 43 \ 4 Scan153 | |
| Performance test results for Magneto No 98034 and No 98033. | 28th Feb 1929 | Box 43 \ 4 Scan154 | |
| The sourcing of a Watford Magneto for aero engines, advocating for a second, British supplier. | 2nd Mar 1929 | Box 43 \ 4 Scan155 | |
| Issues with modified B.T.H. magnetos and the subsequent request to fit Watford magnetos on an 'F' Type engine. | 5th Mar 1929 | Box 43 \ 4 Scan156 | |
| Cancellation of a memo regarding fitting Watford magnetos to an 'F' Type engine for a type test. | 5th Mar 1929 | Box 43 \ 4 Scan157 | |
| Test report for two Watford IS12 Aero Magnetos (Nos. 98033/4) after an overhaul and bench test. | 6th Mar 1929 | Box 43 \ 4 Scan158 | |
| The transfer of I.S.12 magnetos which are Air Ministry property. | 10th Apr 1929 | Box 43 \ 4 Scan159 | |
| Inspection report on two Watford IS.12 Aero Magnetos that were not altered to the required 300° range. | 15th Apr 1929 | Box 43 \ 4 Scan160 | |
| Limited 15° range of reconditioned Watford I.S.12.Aero magnetos and a proposal for their conversion to 30°. | 17th Apr 1929 | Box 43 \ 4 Scan161 | |
| Limited range of reconditioned magnetos and a proposal for their conversion. | 17th Apr 1929 | Box 43 \ 4 Scan162 | |
| The required 30° range for Watford I.S.12 magnetos. | 19th Apr 1929 | Box 43 \ 4 Scan163 | |
| Requesting the type test report specifies the materials used for gear wheels in the Watford I.S.12 magnetos on engine No.13. | 22th Apr 1929 | Box 43 \ 4 Scan164 | |
| Return of Watford IS.12 magnetos from a test engine for material examination of the distributor gears. | 23th Apr 1929 | Box 43 \ 4 Scan165 | |
| The material of distributor wheels for Watford magnetos on Type Test Engine No. 13. | 23th Apr 1929 | Box 43 \ 4 Scan166 | |
| Cover note for a report on preliminary bench tests of Watford IS12 aero magnetos. | 23th Apr 1929 | Box 43 \ 4 Scan167 | |
| Instructions regarding the bench testing of two overhauled Watford IS12 aero magnetos. | 6th Mar 1929 | Box 43 \ 4 Scan168 | |
| Instructions and results for a type test, detailing adjustments to a safety gap and electrical performance figures. | 8th Dec 1924 | Box 43 \ 4 Scan169 | |
| The despatch of two Air Ministry magnetos for timing range modification. | 29th Apr 1929 | Box 43 \ 4 Scan170 | |
| Seeking instructions for the disposition of Watford aero magnetos. | 16th May 1929 | Box 43 \ 4 Scan171 | |
| Request to order two distributor terminal spanners for Watford aero magnetos from Messrs. North & Sons. | 2nd Jun 1929 | Box 43 \ 4 Scan172 | |
| The modification and allocation of Watford Aero Magnetos. | 6th Jul 1929 | Box 43 \ 4 Scan173 | |
| The examination of Watford IS.12 Aero Magnetos after a failed type test. | 7th Jul 1929 | Box 43 \ 4 Scan174 | |
| Enquiry response detailing the materials of gear wheels in dismantled Watford IS.12 Aero Magnetos. | 19th Aug 1929 | Box 43 \ 4 Scan175 | |
| The condition of disassembled Watford IS. 12 Aero Magnetos from test engine F.14/MS13. | 20th Aug 1929 | Box 43 \ 4 Scan176 | |
| Test report on Watford IS12 aero magnetos following a 53-hour run on a 714S-13 engine. | 19th Sep 1929 | Box 43 \ 4 Scan177 | |
| Page 2 of instructions detailing a magneto's superior features and test performance on an 'R' development engine. | 9th Dec 1924 | Box 43 \ 4 Scan178 | |
| Recommendation to use magnetos from the British manufacturer Messrs Norths over the American-controlled B.T.H. | 8th Dec 1924 | Box 43 \ 4 Scan179 | |
| Comparison between B.T.H. and Watford magnetos of lightened type for 'R' engines. | 20th Sep 1929 | Box 43 \ 4 Scan180 | |
| Weaknesses observed in magnetos on 'R' engines, caused by the use of magnesium alloy. | 20th Sep 1929 | Box 43 \ 4 Scan181 | |
| The inspection of magnetos, discussing faults, the use of magnesium alloy, and performance after a race. | 20th Sep 1929 | Box 43 \ 4 Scan182 | |
| The testing and performance of Watford magnetos for 'F', 'H', and 'R' type engines. | 20th Sep 1929 | Box 43 \ 4 Scan183 | |
| Report comparing Watford, B.T.H., and Messrs. North aero magnetos, recommending the use of North's products. | 24th Sep 1929 | Box 43 \ 4 Scan184 | |
| Suggesting the standardisation of Watford magnetos on aero engines, citing dissatisfaction with B.T.H. magnetos. | 24th Sep 1929 | Box 43 \ 4 Scan185 | |
| Table listing the status and allocation of 'R' Aero Engine Magnetos. | 25th Sep 1929 | Box 43 \ 4 Scan186 | |
| List of Watford Aero Magnetos, detailing their type, serial numbers, and status. | 29th Oct 1929 | Box 43 \ 4 Scan187 | |
| Requested modifications for Watford IS12 magnetos following a visit to a supplier. | 11th Nov 1929 | Box 43 \ 4 Scan188 | |
| Letter regarding the return and modification of Watford I.S.12 aero magnetos. | 11th Nov 1929 | Box 43 \ 4 Scan189 | |
| Page 2 of a letter to Messrs. North & Sons, Ltd. regarding arrangements for the return of magnetos. | 11th Nov 1929 | Box 43 \ 4 Scan190 | |
| Letter to Messrs. North & Sons, Ltd. regarding the dispatch and return sanction for Watford L.S.12 Magnetos. | 12th Nov 1929 | Box 43 \ 4 Scan191 | |
| The return of Watford IS12 magnetos for slight modifications. | 12th Nov 1929 | Box 43 \ 4 Scan192 | |
| Return of specific Watford type magnetos to Messrs. North for modification. | 19th Nov 1929 | Box 43 \ 4 Scan193 | |
| Tooling costs, pricing, and supply arrangements for Watford I.S.12 magnetos for aero engines. | 26th Nov 1929 | Box 43 \ 4 Scan194 | |
| Inquiry to Messrs. North & Sons, Ltd. regarding the ownership history of four Watford type IS.12 Aero Magnetos. | 3rd Dec 1929 | Box 43 \ 4 Scan195 | |
| Strategy for ordering Watford and B.T.H. magnetos in consultation with the Air Ministry. | 4th Dec 1929 | Box 43 \ 4 Scan196 | |
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