206 University Geological Survey of Kansas. 
Methods of Timbering. 
Very ,few mining operations are possible or practicable 
without more or less timbering. The quantity and quality 
of timber used varies considerably, however, with the charac- 
ter and value of the mineral mined. 
The primary object of timbering is to furnish temporary 
support for the roof and walls, the timbers being so arranged 
that they provide protection for the miner while he carries 
on the work of prospecting, exploring and removing the ore. 
In soft ground a drift can be advanced by means of support- 
ing and protecting timbers, the miner simply removing the 
material enclosed within the supports, which are advanced 
from time to time. When in soft ground an ore body is 
‘reached by such a timbered passage or drift, its size may be 
enlarged by diverging the advancing timbers. The size of a 
drift is, however, limited, and ranges from sixteen to eighteen 
feet in width to 20 and 30 feetin height. Aslong timbers strong 
enough to withstand the burden of the superincumbent rock 
mass must of necessity be large and unwieldy to handle, they 
are seldom used. The principal objection, however, is the 
difficulty experienced in introducing the timbers into the 
mine, owing to the drifts being too narrow, and the corners 
and curves too abrupt. However, by economizing in tim- 
bers, the difficulty is partially overcome, which is accom- 
plished by using the posts of the original drift timbers as one 
of a set of posts for side drifts. This method is employed 
when it is desired to broaden the workings, as in the case of 
removing a slice in soft ground. If ore is found in paying 
quantities on one or both sides of a drift, side drifts may be 
run on either or both sides of the original drift. This opera- 
tion can be repeated as often as desired by simply adding 
the capping timbers, or caps, and one row of posts to the sets 
already in position. It is evident that for one drift one cap, 
two posts and a sill are required for a set; for three drifts, 
three caps, four posts, and three sills, etc. 
The height of a drift can be increased by elevating the ad- 
vancing timbers, 7. ¢., by lengthening the posts until the limit 
in height of timbering is reached, after which side drifts are 
