Copy letter from an unknown correspondent, to The Direct Photo-Engraving Company, 38 Farringdon Street, E.C. 'Your estimate for Prof. [Professor Walter Noel] Hartley's plate (£5-10-0) is now accepted, and you may put it in hand. The copy is with you. In addition we require a photo block of the inclosed small spectrum, to go in the text. It should be somewhat larger than the print herewith. The negatives can be supplied, and will be sent to you by Prof. Hartley when he returns to Dublin in about a week's time, unless you hear from him that he objects to reversing the spectrum, in which case you [faded word] to work from the positive'. 27 July 1894