GET ROPERIVES OR BULEDING SLONES, LTC. 345 
author believes, that for the sake of uniformity, at least, it would 
be best to apply the bearing faces directly to the steel plates of 
the machine, a spherical compression block being used in mak- 
ing the test. Record should be kept of the direction in which 
the pressure is applied with respect to bedding. 
The load at which the cubes are first cracked, the ultimate 
strength, the perfection of the resulting pyramids, and the explo- 
sive manner in which the cubes break should be carefully noted. 
The crushing strength per square inch is computed by dividing 
the ultimate strength by the average area of the bearing surfaces 
in square inches. 
Transverse strength.—The transverse strength is measured in 
terms of the modulus of rupture. This is the force required to 
break a bar of any material one inch square, when resting on sup- 
ports one inch apart, the load being applied inthe middle. The 
determination of the modulus of rupture is of far greater impor- 
tance in masonry construction than would be supposed from the 
very meager data available. The broken lintels, caps, and sills 
which are so conspicuous in many of the larger buildings in this 
country, testify to the need of a more general appreciation of 
the value of this test. Many building stones that are perfectly 
suited to withstand the compressive stresses in the body of 
the wall, have such a low modulus of rupture as to be 
unfit for use in a position where a high transverse strength 
is required. 
The necessary thickness of a lintel, cap, or sill depends mainly 
upon the transverse strength of the stone. In order to avoid 
possible danger from weak stone or unequal stresses, the doors 
and windows of the heavier buildings are often arched. 
For the purpose of obtaining the modulus of rupture, pieces 
should be prepared by sawing, and should have a cross section 
of one square inch and a length of from six to eight inches. 
The sides should be smooth and the opposite faces parallel. 
The pieces thus prepared should be placed in a testing machine, 
in which both ends are supported and the pressure applied in the 
middle. The weight required to break the sample and the 
