Letter from B. Murphy, Harry W. Cox & Co., Ltd., Tennyson House, 159 Great Portland Street, to James Mackenzie Davidson A report on the question of small power equipments for use at the front. Mr. B. Murphy provides Mackenzie Davidson with considerations for two methods - 'Petrol electric set direct coupled to high tension rectifying switch' and 'Petrol electric set driving a synchronous motor on the existin shaft of which is mounted a rectifier'. Also comments that it is a pity no manufacturers have been given the facilities to see how X-ray units are employed at the front, as the ability to do so would give them more knowledge of the kind of difficulties that arise. 7 February 1918