230 University Geological Survey of Kansas. 
ground. That part of the jig room containing the jigs is al- 
ways floored, while the remainder of the room may have an 
earth floor, generally covered with a bed of tailings. This 
necessitates one part of the floor of the jig room being sev- 
eral feet lower than the other; the lower part containing the 
rolls and elevators, also the crusher, which, however, stands 
upon a framework which raises it to the level of the crusher 
room floor. The coal bunker is adjacent to the boiler room, 
the open side of which faces the boilers. For a typical plan 
of this form of mill pre see figure 33. 
REVOLVING 
eoue | 
ITAILINGS 
ELEVATOR 
DSSS SSS SSS SES 
EVATOR 
RSSSSSSSSSSSS 
L 
-_ 2 => 
E 
ELEVATOR 
Z 
LLL LOL hI adda [PEEL 
Fig. 33. Plan of jig room, showing position of machinery. 
Another form of building which seems to be growing in 
favor is shown in plate XXXIV. This style of structure has 
a broken slope roof, one large roof covering nearly all the ma- 
chinery, which is enclosed within its four walls. Low par- 
titions separate the engine and boiler rooms and other parts 
of the mill from the jig room. 
The advantage of this form of building over others is that 
one can take a position commanding a view of the whole plant, 
when the whole operation of crushing, screening, jigging, 
etc.—in fact, the whole process of concentration—can be seen 
at a glance, with the laborers at their respective posts. Any 
break in the machinery can also be readily detected, as well 
as any defects in the plan of the work. It also obstructs the 
light less than the other styles of buildings. 
The tailings elevator is erected at the jig room end of the 
