168 OIL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN, [bull. 212. 
two derrick men, and the fireman— with a corresponding night shift, 
as the work proceeds night and day. 
Fig. 12.— Derrick with machinery in place. 
The work progresses rapidly at first, but becomes slower as the drill 
goes downward. Great care is required to keep the drill in motion 
