1911.] Tlie Causes and Prevention of Miners' Nystagmus. 19 



Xystagmus is four times more common in England and Wales and lamps 

 are used more than three times more frequently than in Scotland. (All the 

 Scottish cases may have come from safety-light pits.) 



Table XIV.— (My Figures.) 





No. 



Latent. 



Receiving compen- 

 sation. 



Safety-light pits ".. 392 



38 



354 

 3 



I have drawn up another table in which I have separated my local cases 

 from the rest. My complete figures represent a good average of the whole 

 of England and Wales. 



Table XV. 





England and Wales. 



Ehymney Valley. 



Men employed. 



Percentage of 

 nystagmus. 



Men employed. Percentage of 

 r J nystagmus. 



Naked lights 

 Safety 



8 -4 or 1 

 81 -6 9 7 



99 -01 111 -2 



12 or 1 2 -66 or 1 

 88 7-5 97-34 36"5 



In England and Wales the percentage is 1 to 12*5, in the Ehymney Valley 

 1 to 5. Of the eight cases from house-coal or naked-light pits five had 

 worked in safety-light pits ; five were unaware of the fact that they had 

 nystagmus. 



Of the three cases who were bad enough to fail, one was so deaf that I 

 could get no history, one had worked seven years with safety lamps, and 

 the third (Case 6) developed nystagmus immediately after the shock 

 following the Darran explosion, in which he was one of the survivors. He 

 had no trouble with his eyes before. 



Murton Colliery, Sunderland, is a very large colliery, and the only one. 

 in England where electric lamps have been extensively used for years. In 

 reply to a letter of mine asking for information, Mr. Wood sent me the 

 following : — " Nystagmus. — Our cases have been so few and far between that 

 I have no information of value to give you." ISTo comment is necessary. 



In one district which I visited the men complained to me that the oil 

 used in a certain colliery was very poor in lighting quality. I saw the 



C 2 



