COMPARATIVE VALUE OF VARIOUS KINDS OF STONE. 



35 



Results of experiments on specimens 5, 6, 7, 8, fractured 

 and crushed at right angles to the cleavage. 



By the foregoing experiment it will be observed that the 

 resisting powers of stone to compression, are greatest when 

 the pressure is applied perpendicularly upon the bed or 

 laminated surface, and that in the ratio of 100 : 82 in the 

 force required to fracture, and 100 : 86 in the force required 

 to crush this description of stone. Hence, as already observed, 

 the powers of resistance of every description of laminated 

 stone, are most effective when the beds are placed horizontally 

 or perpendicularly to the direction of the pressure, and this 

 position is the more important when the stone is exposed to 

 the atmosphere, as it partially prevents the absorption of 

 moisture, which in winter tends to destroy the material by the 

 contraction of the stone and the expansion of the water at low 

 temperatures. 



Experiments to determine the force required to fracture 

 and crush h'w., l£in., and 2in. cubes of stones from Scotland, 

 Wales, and other places. 



