I 



TEEATMENT OF THE COMSTOOK OEES. 215 



boring stamps. If the stamps are allowed to rise and fall in regular succes- 

 sion, from one end of the battery to the other, the material is usually found 

 to accumulate at one end, and the effective duty of all the stamps greatly 

 diminished. The order must therefore be varied. In a five-stamp battery a 

 common arrangement is to let fall first the middle stamp, then the end stamp 

 on the right, then the second stamp on the left, then the second stamp on 

 the right, and finally the end stamp on the left. The order in which the 

 stamps are to fall being determined, it is carried into effect by fixing the 

 cams on the shaft in such position that each cam, by the revolution of the 

 shaft, will lift its respective stamp at the desired moment. For this purpose 

 the key-seats cut in the hub of the cam must be determined with care ; one 

 common key-seat being cut on the cam-shaft, when the desired position of any 

 given cam has been ascertained, the key-seat in the hub is cut to correspond 

 with that of the shaft. 



When it becomes necessary to hang up a stamp so that the cam may 

 revolve without reaching the tappet, it is supported by a prop or stud, n, 

 which is shown in the drawing on Plate XIX. The lower end of the studs, of 

 which there is one for each stamp, is pivoted on a small shaft fixed across the 

 battery from end to end, resting in boxes, which are secured to the uprights. 

 Each stud is just long enough to support the stamp, when placed under the 

 tappet, at a height which is about an inch above the highest lift given by the 

 cam. To bring the end of the stud into this position, when desired, the work- 

 man lays a smooth stick on the face of the cam as it is rising to the tappet, 

 and holds it there while the stamp is lifted. The stick is as wide as the face 

 of the cam, long enough to be held convenient! j,^ and an inch and a half thick 

 at the end which comes between the cam and tappet. By this means the 

 stamp is raised high enough for the stud to be put in place, which being done, 

 the stamp is supported above the reach of the cam. To set it again in motion 

 the operation is repeated, the stud being withdrawn at the moment when the 

 stick on the face of the cam has lifted the stamp clear of its support. 



In Nevada the weight of stamps in most general use is between 600 and 

 700 pounds. They are usually run at about 70 or 80, sometimes 90 or even 

 100, blows per minute; they drop from 7 to 10 inches, according to their 

 speed, the greater number of blows per minute requiring shorter lift. In 



