Letter from [Alan Archibald Campbell] Swinton, to The Editor, "The Wireless World" Informs he is giving a paper to the Wireless ociet of London on 1 June, on the subject of "A Universal Amplifier Suitable for all Wavelegnths", and is anxious to obtain diagrams prepared both for the purpose of making lantern slides and also to illustrate the paper, hoping he can be put in contact with someone capable of making the diagrams from sketches. 18 May 1921