224 University Geological Survey of Kansas. 
ably more often operated by steam than with air, although 
admittedly poor practice. 
The drills are mounted in one of two ways, namely, on 
tripods and columns. The column can be placed either ver- 
tically, horizontally, or at an angle with the vertical or hori- 
zontal. When used horizonally, it is in the position in which 
it is used in shaft sinking, and has received the name of 
‘‘shaft bar’’ from that work. The range of application of a 
drill, either on a tripod or column, is considerable, both hori- 
zontally and vertically, while the frequency of the stroke 
permits rapid work with comparatively little wear and strain 
on the cutting tool or bit. 
The drill consists of a reciprocating iron plunger or piston 
from two to four inches in diameter, which is driven back 
and forth in a cylinder by means of compressed air or steam. 
The fore end of the cylinder is formed into a long bearing 
through which the plunger, bearing the drill or bit, recipro- 
cates. The outer end of the plunger rod bears a chuck into 
which is fastened the bit. The cylinder, with its valves and 
various other attachments, is mounted upon an adjustable 
base, provided with a feed screw for the purpose of advancing 
the cylinder to the surface to be drilled, and thus feeding the 
drill forward. Plate XXV. 
The entire machine is mounted upon a shaft bar, a tri- 
pod, or a vertically placed column. The air or steam is ad- 
mitted to the cylinder by a valve at the top and is fed to 
the drill through a hose, which is protected with wire. The 
drill makes from 400 to 600 strokes per minute, and is pro- 
vided with a ratchet, so that a rotary motion is given to the 
bit, the rotation taking place on the return stroke. 
The bit is turned generally about one-eighth of a revolution 
per stroke, The stroke of the plunger, and, therefore, the 
bit, is from three to four and one-half inches. The rate of 
cutting in very hard rock (flint) is about one-half to one inch 
per minute, or from eight to sixteen feet per shift of eight 
hours—that is, with a one and one-half or twoinch bit. The 
entire feed is about two feet, and is intended to be operated 
by hand, although automatic feeding devices are occasionally 
