V54 NEW YORK STATE MUSEUM 



of material that would be lost from a square yard of pavement laid 

 in the street. 



Mr Jones gives the following test made at Geneva. 16 different 

 samples were at his disposal; in order to eliminate the weakest, he 

 put two of each kind of brick into the staves of the machine, with 

 the usual charge and number of revolutions. The result was that, 

 while the strongest material lost less than 3^, the weakest lost 

 Y.35^. The wire-cut brick failed to develop as much strength 

 as the same material repressed. In one instance, the difference of 

 abrasion was as between 3.59^ in the case of repressed brick and 

 6.26,'?^ for common wire-cut brick. The large fire clay blocks also 

 failed in comparison with the smaller repressed fire clay bricks. 



Some of the comparative results reached by Mr Jones's test were 

 as follows: 



Abrasive 



loss 



Shale block no. 1 2.46^ 



Medina sandstone block 3.61;^ 



I'ire clay block no. 2 3.2^ 



Tire clay block no. 3 4.6^ 



The method adopted by Mr Jones is undoubtedly from all ap- 

 pearances very reasonable, but, in order to determine whether it 

 or the old method of testing the resistance of brick to abrasion 

 is the better, it will be necessary to carry on a long series of parallel 

 tests on the same material, using both methods. Steps have already 

 been taken to do this, by the l^ational brickmakers association. 



More recently Prof. Talbot of the University of Uliriois has 

 brought forth a third method of testing paving brick which differs 

 from' the standard test of the IsTational brickmakers association in 

 placing a certain number of bricks in the standard I^. B. M. A. 

 rattler, along with cast iron shot of two sizes, the larger weighing 

 about T-| pounds, the smaller about 1 pound. 



A committee lately appointed by the association referred to 

 above found that, while the Jones device gives more accordant or 



