364 Report of the Committee on Colour- Vision. 



vivid red skein, like the red flag used for signals on railways, a 

 bright, yellowish-red, a scarlet. The red blind will match the 

 sample with a dark green or dark brown with shades which to 

 the normal eye are darker than scarlet. The green blind will 

 select light green or light brown to ma,tch the scarlet shades 

 which are lighter than the sample. 



" Yours faithfully, 

 (Signed) " W. J. HARNETT. 



" W. Latta, Esq." 



" Metropolitan District Railway, 



"Manager's Office, 

 " Parliament Mansions, Yictoria Street, 



" London, S.W., 



"July 17th, 1890. 



" Sir, — Your letter of the 16th ultimo, addressed to the 

 Secretary, respecting the various tests for Colour Vision, 

 has been handed to me, and I beg to reply to your several 

 questions as follows : — 



" The tests are applied by the Company's Medical Officer, Dr. 

 R. Bligh Wall, of 72, Bishop's Road, Bays water. His test is by 

 means of coloured wools, the person under examination having 

 to name a given colour, and in some cases he is required to match 

 colours. 



" Any application to attend one of your meetings to explain 

 the methods in detail, if addressed to Dr. Wall, will, I have no 

 doubt, receive his best attention. 



" I send herewith samples of the different coloured glass in use 

 for the different signals, viz., red and green, as well as sample 

 pieces of bunting used for hand signals. With respect to the 

 fixed day signals, in the case of those known as ground discs 

 which depend on colour, the pigment used is known as Bennett's 

 Enamel White Paint, and Bennett's Vermilion Fluid Enamel, two 

 specimens of which I enclose. 



" I am, Sir, 



" Your obedient Servant, 



"ALFRED POWELL, 

 " Capt. W. de W. Abney, " Manager. 



" The Royal Society." 



" London, Chatham and Dover Railway, 

 " Secretary's Office, 



" Yictoria Station, Pimlico, S.W., 



July Iteh, 1890. 



" Sir, — In reply to your letter of the 16th ult. as to the steps 

 taken in this Company to test the Colour Vision of the employes, 

 I beg to inform you that the test used in our Locomotive Depart- 

 ment is the same as that in the Army. It is a test in colours and 

 dots on a ca^d. I enclose a copy of the card, as well as the 



