Smithsonian Report, 1907.—Parsons. PLATE II. 
| l 
her 
{Rizco] 
AN ENLARGED PHOTOGRAPH OF A HARDENED STEEL FILE, 
SHOWING THE DESTRUCTIVE ACTION OF STEAM AT HIGH 
VELOCITIES. 
This file was exposed for 145 hours to the action of a jet of steam at 
100 pounds pressure, discharging into a condenser pressure of 1 
inch absolute of mercury. 
