18 



Dr. T. L. Llewellyn. 



[Dec. 19, 



In this table some of the collieries, having more than one seam, appear 

 more than once. The thinnest seam I visited was at Eadstock, near Bath, 

 through the courtesy of Mr. G-. McMurtrie. The seam was from 12 to 

 14 inches thick, and all work was done on the side. The pit was lit with j 

 candles and no case of nystagmus had been heard of in the district. I 

 examined men at the face. AH told me they had no trouble with their 

 eyes and that they had never heard of the disease. There was one very 

 slight case of nystagmus in a man who had worked in a steam-coal pit, but 

 who assured me he had never had any trouble with his eyes. 



Light. 



The great difference between a coal pit and a metalliferous mine is that in 

 the coal mine a safety lamp is often required. In the Cornish tin mines 

 candles are used and no nystagmus is present. 



In reply to a letter of mine Dr. J. Telfer Thomas kindly sent the 

 following : " I have been in practice in the mining district of Cornwall for 

 the past 23 years and have never seen a case of miners' nystagmus there. 

 .... It does not attack tin miners." 



There is a great difference between the light given by a candle and that 

 from a safety light. The candle gives more light, remains constant through 

 the day, throws no shadows, and, most important of all, can be placed very 

 much nearer the coal face. Some miners place the candle under the ledge of 

 coal they are undercutting. The safety lamp gives less light, quickly becomes 

 dirty, throws shadows, and must be placed out of reach of the pick. The 

 bonnet and oil reservoir cut off much of the light and produce an area of 

 darkness above and below the lamp. (Court lays stress on all these points.) 

 My figures show as far as I am able to do so the relative percentages 

 between the two classes of pits. 



In Somersetshire and the Forest of Dean nystagmus is practically 

 unknown. Both are naked-light districts. Through the courtesy of the 

 Home Office I am able to give the figures for Scotland apart from those of 

 the rest of the Kingdom. 



I have made a table from these figures and from the Blue books (30, 31). 



Table XIII. 





Scotland. 



Rest of Kingdom. 





55 



0-05 

 28 -2 



1563 

 0-21 

 91 -6 



Percentage of cases to men underground 

 Percentage of safetv lamps used (31)... , 



