532 



STUDIES FOR STUDENTS 



per square inch. The average transverse strength of the Mon- 

 tello granite was over 3780 pounds per square inch. The 

 samples broke suddenly, and the fracture extended diagonally 

 across the center of the pieces. 



The modulus of rupture was determined for samples of lime- 

 stone from eight different quarries. The results ranged from 

 1 164.3 pounds to 4659.2 pounds per square inch. The highest 

 result obtained was on a sample of stone from the Laurea Stone 

 Company's quarry at Sturgeon Bay. The stone from the Marble- 

 head Lime and Stone Company's quarry at Eden gave a modulus 

 of rupture of 3632 pounds per square inch. All of the trans- 

 verse strength tests were high. The samples broke very close 

 to the center and much quieter than the granite. 



The modulus of rupture was determined for sandstone from 

 six different quarries. The results ranged from 362.9 pounds to 

 1324 pounds per square inch. The highest test obtained was on 

 samples from the Chicago & Northwestern Railway Company's 

 quarry at Ablemans. Eight tests of the brown sandstone from 

 the Lake Superior region gave an average modulus of rupture 

 of about 500 pounds per square inch. 



A comparative examination of the results shows that the 

 finely crystalline limestone possesses a higher modulus of rupture 

 than either the sandstone or granite. However, it is ordinarily 

 less rigid than either of these stones, and is more liable to sag 

 when suspended at the ends. 



TABLE II 



TRANSVERSE STRENGTH 

 Modulus of Rupture in Pounds per Square Inch 



Highest test 



Lowest test 



Average 



Granite and rhyolite : four samples from two 

 different quarries 



Limestone : ten samples from eight different 

 quarries 



Sandstone : sixteen samples from six different 

 quarries 



3.909-7 

 4,659.2 



1,324 



2,324-3 



1,164.3 



150.2 



3,i56-2 

 2,761.15 

 558.8 



