CRANE.| Prospecting and Boring for Mineral Waters. LIL 
water in the case of the diamond and calyx drills also tends to 
loosen the soft formation of the walls of the hole, but not to 
such an extent as does the rubbing of the rope in the churn-drill 
method. 
With the churn drill the hole is made sufficiently large to 
allow the placing of the casing without extra enlargement. 
The operation of casing is, in this case, then, quite simple—the 
casing can be driven from time to time without removing the 
line of tools. ‘This is accomplished by raising the tools until 
the middle of the sinker-bar comes to the top of the casing; a 
driving block is then clamped to the bar, which, being raised 
and dropped will drive the casing down. Sections are added 
as needed until the full depth has been lined. When drilling 
is done by diamond or calyx drills, the hole must be reamed 
out to make room for the casing, provided casing is necessary 
during drilling operations. Reaming will then alternate with 
drilling. 
It is often necessary to shut off certain strata to pervent the 
contamination of the desired product, as when oil, gas and 
briny-water strata overlie the sheet of water which it is desired 
to open up. Such strata may be closed after the hole is com- 
pleted, but it is usually preferable to close the same as soon as 
possible after penetration. Quicksand strata must be closed at 
once, or further work of drilling will be interfered with, and 
there will also be the risk of a cave-in. 
It was formerly necessary to remove the bit and core-barrel 
and substitute for them a reamer, but within the last few years 
a reamer has been devised by means of which drilling and 
reaming may be carried on simultaneously, thus allowing the 
casing to be placed and driven from time to time independent 
of drilling operations. The driving of the casing is accom- 
plished in this case by an improvised pile driver, the rod being 
removed during the operation. 
When it is especially desirable to close the strata as soon as 
passed through it may be done by a new device lately brought 
into practical use, which is intended, however, for shallow 
work only, as working gravel beds and superficial coverings. 
