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EXPLORATION GEOPHYSICS 



Loading Poles. — A spear pole often is employed for placing the 

 charge at the bottom of a hole filled with drilling mud or water.f The 

 procedure is illustrated in Figure 540. The charge is held on to the spear 

 by keeping the wires under tension. The poles are usually 15 feet in length 

 and are provided with link couplings to give the required depth of place- 



FiG. 539. — Approved procedure for loading shot holes. A, ex- 

 plosive; B, cap wires; C, loading poles; D, hose for filling hole 

 with water; E, shooting truck with water tank; F, radio antenna. 

 (Courtesy of Standard Oil of New Jersey.) 



ment. When the charge has been pushed to the bottom of the hole the 

 tension on the wires is released. A jerk on the pole then frees the spear 

 and leaves the charge in place. Figure 541 shows a form of locking link for 

 connecting the lengths of pole together. 



When loading charges into holes which are two hundred feet or more 

 in depth or where caving and "sluffing" of the wall are common, a weighted 

 brass "spoon" is operated by a steel cable and winch. (Figure 542.) The 

 charge is held in the spoon by two or three loose loops of wire which will 

 allow it to slide off easily when the tension is released on the firing wires. 

 The tubing above the spoon is filled with lead and the total weight is from 

 400 to 500 pounds. Using this method of loading, a charge may be pushed 



t O. W. Lundblad, "Lowering Device," U. S. Patent 2,430,182, May 6, 1947. 



