1911.] The Causes and Prevention of Miners Nystagmus. 



17 



(2) In thick seams, or where the pressure is great, one edge of the coal is 

 .freed and the coal forced out with a bar. In comparison with the last 

 method little skill is required, except in the care of the roof. 



(3) Coal cutters. Here the men are more like labourers and not skilled 

 workmen. 



Table IX* 



Much holing 

 Some „ 

 Little „ 



Table IXa. 



Of the 111 cases holing wa 



On side 



On knees 



With body inclined 



* This table applies to colliers only ; a few c 

 one time are added. 



s where the man had been a collier at 



Table X. — Figures given by Eeturns made from 43 Collieries (one district). 





Collieries. 



Percentage of nystagmus. 



Little or no holing . . . 



30 

 13 



0-69 

 0-79 



Thickness of Seams. 



The thickness of seam does not appear to be of great importance, but as I 

 ^m unable to give the relative proportion of men working in the several 

 .seams my figures are not so valuable as they might be. 



Table XL— Thickness of 



Less than 2 feet 



2—3 feet 



8 feet and over 72 



Three men had worked with coal cutters. 



Table XII. — Eeturns from 43 Collieries. 



Seam. 



No. of collieries. 



Percentage of nystagmus. 



Less than 3 feet ... 



16 



0-81 



3— 4 feet 



14 



0-54 



4—5 „ 



14 



0-80 



5—6 „ 



5 



0-58 





6 



0-41 



VOL. LXXXV. — B. 



