Copy letter from Alfred George Hastings White to T E S Cooper, 19 Birdhurst Road, Croydon 'Dear Sir, With every desire to be of assistance to enquirers, when reasonable possible, I much regret that we are unable to help you in your request for references to the use of acetylene in photometry. It would require a general search, for which we have no provision, our time being fully occupied in routine work. The subject is also somewhat technical, and I should suggest that the Society of Arts of the Patent Office library would be more appropriate places to enquire.' 28 July 1909