Smithsonian Report, 1910. — Beyer 



Plate 7. 



View in Nail Mill. Showing Safety Hoods Over Emery Grinders, which are 

 Flanged Out of a Solid Piece of Steel Plate. 



The foot treadle must be held down while the grinder is being used: as soon as the treadle 

 is released a spring throws the overhead belt on to the "loose" pulley, stopping the 

 grinder automatically. Walks for oilers will be noted in the trusses at the top of picture; 

 in this ease they are* fenced in with boards, although pipes or structural railings are 

 frequently used. 



