CLAY WORKING INDUSTRIES. 



201 



End cut auger brick , 

 Side cut auger brick . 



Absorption. 



.73 



.72 



Rattling. 



18.25 

 17.78 



Crushing 

 sq. in. 



5,318 

 6,925 



Crushing 

 cu. in. 



1,322 

 1,649 



Rank. 



By still further eliminating the causes of variation in these samples, 

 aside from the effect of the mode of manufacture, the following figures 

 are deduced. 



Four samples of end cut repressed auger brick made of shale clays, 

 against eight samples of side cut repressed auger brick, also made from 

 shales. 



In this last comparison, the sources of variation have been largely 

 eliminated and the results are therefore much more valuable; as will be 

 ssen, they point strictly to the general superiority of the side cut brick 

 over the end cut. 



In order to test the matter still more fully, five side cut common 

 bricks made from a sedimentary river clay and five end cut bricks from 

 the same clay and same factory, were burued side by side in a kiln of 

 sewer pipe. When burnt and glazed, they were put into a rattler with 

 some other material for special test and were given 1,000 revolutions. 



The bricks were fortunately much too soft to develop the quali- 

 ties of the clay, the heat having been too low and not continued long 

 enough to vitrify them. 



The results showed more abrasion of the side cut bricks thau of the 

 end cut, but with this important difference; that the five side cut bricks 

 were represented at the finish by four pieces representing each a brick, 

 and two pieces which could be fitted together, representing one brick. 

 The abrasion had stripped off all edges and corners, but had left the main 

 core or section of the stream of clay as it came through the die, intact 

 and recognizable. 



In the end cut bricks, however, the fragments were, one brick, four 

 half bricks, representing two whole ones and seven fragments represent- 

 ing two other bricks, showing that while the fragments left, showed more 

 actual collective weight, yet the side cut bricks had far the best of the 

 test in the condition of the bricks coming from the rattler. Only one of 

 the end cut bricks was in as good condition as four out of five of the 

 side cut. 



