CLAY WORKING INDUSTRIES. 145 



2. A similar cylinder, with its frame and spider wheels inside, by 

 which the dirt is kept in agitation all the time. 



3. A similar cylinder, covered with wire cloth, and provided with a 

 set of flites or buckets inside which carry the dirt up on one side and 

 throw it violently against the cloth on the opposite side. The dirt in 

 this case only travels along the bottom as it falls from one bucket and is 

 caught by the next. 



4. A hexagon or octagon frame, like No. 1, which has the advant- 

 age of carrying the dirt up on its angles and letting it slide back with 

 some force when its equilibrium is overcome. 



Of these lour types — Nos. 3 and 4 will screen m re clay than either 

 1 or 2 of the same dimensions — they will also use more power. No. 4 is 

 the most efficient rotary screen for the power it uses. No. 3 is the 

 most efficient in screening dirt regardless of power consumed. They 

 are all equipped with various automatic devices for keeping the screen 

 cloth clean from adhering clay; generally knockers or weights dropping 

 in quick succession on the cloth are used. In spite of all the mechanical 

 ingenuity expended on this subject there is absolutely no rotary screen 

 in use in the state that does not require practically all the time of one 

 attendant man or boy to keep it in efficient operation. 



In several cases, a boy was seen at work side by side with elaborate 

 automatic appliances supposed to do away with his services. 



The objections to rotary screens as a class are : 1st. That they use 

 up a good deal of power in doing their work; 2nd. That they require 

 constant attention; 3rd. That they require much repair. 



The points in favor of them are, 1st. That with good construction 

 and careful attention they can be made to do a very large amount of ser- 

 vice per day. 2nd. That they occupy but little space and require but 

 little head room or elevators. 



The shaking screens in use in the state are manifold, but so far as is 

 known, there is only one which is regularly manufactured by a machinery 

 house. The majority of them are the invention and manufacture of the 

 various manufacturers and superintendents who have had the troubles of 

 the other systems to endure, and have tried a new plan as a possible relief. 



The following shaking screens have been observed in use in the 

 state: 



1st. A screen made of perforated metal forty-eight inches wide by 

 twelve feet long, suspended on iron rods from points eight to ten feet 

 above, the amount of inclination being about two feet in twelve, or one 

 in six. The dirt was thrown into the upper end in one stream but 

 divided by a "V" shaped plow, it covered the whole area of the screen. 

 The vibration was given by a small crank and connecting rod and the 

 necessary jerk and recoil was effected by making the frame strike a solid 

 post. 



10 G. O. 



