230 CLAYS AND CLAY INDUSTRY. 



it. As soon as the bar is cut up the bricks are removed. This 

 style of cutter is used for side-cut brick. 



2. At the end of the delivery table there is a revolving auto- 

 matic cutter (PI. XXVI, Fig. 2), carrying a number of short 

 transverse wires, each borne on a fork-like frame at the end of 

 a series of arms corresponding to the spokes of a wheel. This 

 cutter revolves as the bar of clay issues from the die, so> that each 

 wire, as it descends, cuts through the bar. The wheel is so geared 

 that the wire moves with the same velocity as the clay, thus pro- 

 ducing a vertical cut. This cutting device is used for end-cut 

 bricks. In New Jersey tljis type of cutter is used much more 

 than it is in most other states, but its action is not found to be 

 as satisfactory as the preceding one. 



3. Some side-cut machines have the cutting table provided 

 with a wheel carrying several wires in the position of spokes. 

 The centre of the wheel is to one side of the delivery belt, and 

 the plane of it at right angles to> the same. As the clay bar issues 

 from the die, the wheel revolves, the wires cutting the clay and 

 moving forward at the same time. One cut is made at a time. 



The stiff-mud process is adapted mainly to clays of moderate 

 plasticity. It does not work well with stony clays, for the cutting 

 wire is liable to be broken by contact with the stones, necessitat- 

 ing the frequent stoppage of the machine for repairs. These are 

 not difficult to make, but frequent delays are in the long run 

 expensive. The stiff-mud brick, like the soft-mud ones, can 

 be re-pressed, and many face brick are now made by this process. 



The stiff-mud process is a good one, if properly used, but the 

 clays should be thoroughly tempered before molding, and the 

 elimination of a pug mill for reasons of economy is bad. Small 

 molding" machines having a short cylinder have been put on the 

 market, and some small manufacturers, tempted by their cheap- 

 ness, have used them, usually with poor results, for a pug mill is 

 rarely used in connection with them, although a pair of rolls is 

 sometimes substituted for it. This does not, in most cases, do 

 more than break up occasional pebbles. 



Dry-press mid semidry-press process. — This process in New 

 Jersey is restricted to the production of front brick. The clay is 

 powdered and then pressed into steel molds in a dry or nearly dry 



