From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Table detailing the relation of maximum flux through an armature to the sleeve position for a Watford Magneto Type E06d.
| Identifier | ExFiles\Box 48\2\ Scan427 | |
| Date | 1st February 1926 | |
| X.8796 EFC. {E. Fowler Clarke - Electrical Engineer} 1.2.26. WATFORD MAGNETO TYPE E06d. No.73972. Relation of max. flux through armature (Ø) to position of sleeve as determined by movement of cam lever. Sleeve position in degrees measured by cam lever. Corresponding Ø max. position in degrees. Central position of lever taken as 0 advance positive and retard negative (Range 62º) + 31º + 15º 0º - 15º - 31º Total 62º + 22º + 11º 0º - 11º - 23º Total 45º 62º 17º --- HEW. | ||