882 



EXPLORATION GEOPHYSICS 



table drive and separate gasoline-driven water pump. The total weight of 

 the "stretcher" component is about 50 pounds. 



Fig. 555. — Portable drill for shallow drilling. A, engine driving 

 rotary table; B, cathead; C, mud hose; D, swivel head. (Courtesy 

 of Engineering Laboratories, Inc.) 



Water Truck 



Each standard drilling machine is served by a separate water supply 

 truck. Occasionally when the holes are drilled on a closely spaced pattern, 

 or when the distance for hauling water is short, it is possible for one water 

 truck to serve two drill rigs, but this is the exception. In many areas where 

 the location of the source of water is at some distance from the area being 

 drilled, it is necessary to employ two water trucks for each drill unit. 



Figure 557 shows a typical truck-mounted water tank assembly. In 

 addition to the 500-gallon water tank there is also provided a small sturdy 

 "A" frame with guide sheave mounted at the rear. A power winch (not 

 shown) is mounted behind the truck cab and below the water tank. The 



