198 University Geological Survey of Kansas. 
the ore body can be fairly well determined. The floor is 
kept approximately level; that is, at right angles, vertically, 
with the shaft. If the ore body widens out and thickens the 
sides of the drift are generally diverged, and the roof ele- 
vated slightly. 
‘‘Drifting’’ is a term ordinarily applied to prospecting opera- 
tions, and is employed in the search for ore deposits and not 
for working in an ore body itself, as a means of removing 
the ore. It is, however, applied to both, and need not be 
confused if it is borne in mind that in this connection it 
means driving a passageway, either to discover new ore 
bodies or as a means of developing those already known to 
exist. 
Starting on a wall of the shaft, the rock mass is removed 
in much the same way as a shaft is sunk, yet in this case a 
larger surface is generally exposed, which makes it easier to 
cut out, gravity also assisting. The method of cutting is, in 
general, as follows: Near the lower limit of the face of the 
drift, or the part marked out for the face, several charges of 
powder are placed as explained under ‘‘Shaft Sinking.’’ This 
produces a cavity into which the surrounding material can 
be forced; in other words, it ‘‘frees’’ the remaining rock, 
rendering it easy to blast out. A few well directed shots be- 
low square the lower part of the drift, leaving the upper part 
free to be brought down, which can readily be done by plac- 
ing two or three heavy charges at the top of the drift. By 
repeating this the drift is advanced. If the ore body or 
shine shifts to one side, the direction of the drift can be 
altered by simply changing the direction of the drill holes 
and by a judicious arrangement of the same. The arrange- 
ment of the shots is governed wholly by the conditions 
present, which are very variable. When steam or com- 
pressed-air drills are employed, the American center cut sys- 
tem is usually followed. A, figure 16. 
Occasionally the method of procedure is the reverse of that 
given above; 2. e., work is first begun at the top of the drift. 
The reason for beginning at the top of the face of the drift 
is first to advance the roof, so that it can be thoroughly 
trimmed and made absolutely safe and sure, in order that no 
