Miscellaneous Subsurface Methods 



579 



Multiple-shot-angle units are similar to those used on the regular 

 single shot except that a tapered groove is cut in the bottom of the unit 

 in exact alignment with an orienting lug which is photographed in each 

 picture taken by the instrument. Angle units are constructed in maximum 

 drift values of 10 degrees, 18 degrees and 90 degrees. A few units are 

 built as combinations. An 18-degree plumb bob is mounted over a 90- 

 degree angle unit in such a way that both are photographed at once. In 

 this way a well which starts vertically and increases drift to 90 degrees 

 can be surveyed accurately. 



Figure 300. Projector and protractor used for reading multiple-shot film. 



At the present time a special, multiple-shot machine is being de- 

 veloped (fig. 304) . It is designed to save operators rig time in the sur- 

 veying of their wells. The instrument is 1^ inches in diameter and has 

 made test runs in a If-inch diameter bronze barrel. It photographs an 

 angle unit similar to that used with the small single shot except that the 

 plumb bob as well as the compass is housed in a fluid-filled chamber. The 

 control mechanism is a sturdy clock which makes a light contact for illumi- 

 nating and photographing the angle unit. Also it starts and stops an inter- 

 mittent-running motor which winds the film. Various operation cycles 

 may be used by changing contact wheels to accommodate the speed of the 



