128 MINING ESTDUSTEY. 



of timbers 8, 10, or 12 inches square, joined to each other so as to form a con- 

 tinuous piece. The method of joining the sections composing the rod varies 

 in different mines. In the Savage mine the rod is of pine, 12 inches square, 

 each section being 30 feet long, The sections are joined by a simple splice, 

 as shown at a in Fig. 1, Plate IX, and strapped on four sides with iron plates 

 12 feet long, 6 inches wide, and \ inch thick, securely bolted together by 

 bolts 1 inch in diameter. In other mines the sections of the rod are joined 

 in a more complicated manner by a beveled splice and key, as shown at h in 

 Fig. 6, Plate IX, and strapped in manner similar to that just referred to. In 

 the Grould and Curry, Ophir, and others, the square ends of the sections are 

 brought together without any splice whatever, and joined simply by means 

 of the iron straps. In the Ophir the straps on two sides of the rod are 

 formed as shown in Fig. 5, Plate IX, so that a key can be inserted at c. 

 When these keys are driven in as tightly as possible, so as to bring the two 

 ends of the timber closely together and so prevent any lost motion in the 

 action of the rod, the two straps for the remaining two sides are put on and 

 bolted together. 



The motion of the rod is communicated to it from the engine by means 

 of an oscillating "bob," established at the surface. The construction of a bob 

 may be seen by reference to the figures on Plate X, which give the details 

 of one used at the Gould and Curry mine. In the case illustrated the bob is 

 made entirely of wrought-iron. Its method of operation is shown in the 

 drawing on Plate XVI. The pumping engine drives, by means of the pin- 

 ion, the pump wheel, to one side of which is attached, by means of a wrist- 

 pin, one end of the pitman. As the wheel is set in revolution by the engine, 

 the pitman receives a reciprocating motion, the length of stroke being 

 determined by the distance of the wrist-pin from the center of the wheel. 

 The other end of the pitman being connected to the king-post of the bob, 

 causes that to oscillate, giving to the pump-rod in the shaft an upward and 

 downward motion. The upper section of the rod is usually connected to 

 the nose of the bob and the next lower section of the rod by means of a 

 strap and boxes, so as to allow for the vibration caused by the angular motion 

 of the bob; deeper in the shaft the sections are joined together as already 

 shown, forming one continuous piece, which is guided in its movement by 



