TEEATJilENT OF THE COMSTOCK OEES. 221 



The bottom of the pan, like Wheeler's, is flat and has a steam-chamber. 

 The dies ate cast in four quadrant-shaped pieces. In the middle of each 

 piece, on the upper side, is a radial groove or canal, leading from the center 

 to the circumference, which permits the free circulation of the material. 

 A similar space is left between the two adjacent edges of the several pieces. 

 The dies are secured to the bottom of the pan by a dovetailed or wedge- 

 shaped projection, 5 or 6 inches long and from 3 to 4 in width, on the under 

 side of each piece, which, fitting into a similar recess in the pan-bottom 

 holds, them fast. 



The muUer is a circular plate, cast separately from the driver, to which, 

 for use in the pan, it is connected by means of four short uprights or legs, 

 that are bolted both to the driver and the muller. The shoes are attached to 

 the muUer-plate in a manner similar to that by which the dies are secured to 

 the bottom. On the upper side of each shoe is a projection, wedge-shaped 

 in horizontal section, 5 or 6 inches long and from 3 to 4 wide, which fits 

 into an aperture of corresponding form in the muUer-plate, and so placed that 

 the smaller end of the projection follows the larger end in the direction of 

 revolution ; so that the motion of the muller tends to fix the shoe more and 

 more firmly in its place. (See Fig. 4, Plate XXII.) 



The muller, when in place, is raised and lowered, not by a lever below 

 the step-box, as is the case in the Wheeler pan, but by a screw which passes 

 through the hub of the driver and rests with its lower end on the top of the 

 driving shaft. A hand-wheel at the upper end of the screw serves to turn 

 it, raising or lowering the muller, and another hand-wheel, lower down, acts 

 as a jam-nut to keep the muller at the desired height. When the muUer is 

 in motion it may be raised or lowered by arresting the last-named wheel. 

 (See Fig. 3, Plate XXII.) 



To clean the pan up the muller-plate is hfted entirely out by means of a 

 block and tackle. In some miUs this is conveniently supported on a truck, 

 which moves on a railway at a suitable height above the pans. By this 

 means the truck can be brought into position above any one of the pans from 

 which it is desired to raise the muller, and the hoisting apparatus thus 

 applied. 



No guide-plates are used for directing the pulp, the circulation of which, 

 without these contrivances, is very active, the pulp passing fi-om the periphery 



