STATE GEOLOGIST. 



15 



Gillmore. The samples were crushed between steel plates, one of 

 each stone in the direction of the schistose structure, and another 

 in the direction across it, the former being designated as on edge 

 and the latter as on bed, with the following results: — 



, Kind of stone. 



Location of quarry. 



Position. 



Strength in pounds 



of sample. 



per square 

 inch. 



Dark trap rock, 

 massive melaphyr. 



Dark trap rock, 

 from a dyke. 



Gray gabbro, 

 massive, fine. 



Bed, fine syenite. 



Ked, quartzose 

 syenite. 



Taylor's Falls. 

 Chisago Co. 



Tischer's creek. 

 Near Duluth, St. Louis Co. 



Bice's Point. 

 Duluth, St. Louis Co. 



Beaver Bay. 

 Lake Co. 



Watab. 

 Benton Co. 



East St. Cloud. 

 Sherburne Co. 



Pipestone City. 

 Pipestone Co. 



East St. Cloud. 

 Sherburne Co. 



East St. Cloud, 

 Sherburne Co. 



(Probably imperfect sample). 

 Sauk Eapido. 



On bed 

 On edge 



On bed 

 On edge 



On bed 

 On edge 



On bed 

 On edge 



On bed 



105,000 

 105,000 



105,000 

 105,000 



109,000 

 105,000 



106,000 

 103,000 



103,000 



est. 



103,COO 



112,000 

 105,000 



111,000 

 108,000 



105,000 

 103,000 



112,000 

 105,000 



86,000 

 100,000 



26,250 

 26,250 



26,250 

 26,250 



27,250 

 26,250 



26,500 

 25,750 



25,750 



est. 



25,750 



Red, quartzose 

 syenite. 



Bed quartzyte. 



Massive, gray 

 syenite, quartzose. 



Fine-grained 

 gray syenite. 



Fine-grained 

 gray syenite. 



On bed 

 On edge 



On bed 

 On edge 



On bed 

 On edge 



On bed 

 On edge 



On bed 

 On edge 



28,000 

 26,250 



27,750 

 27,000 



26,250 

 25,750 



28,000 

 26,250 



21.500 

 25,200 





Average of 20 samples 





104,800 



26,200 



In order to make a fair comparison, the resultant average strength 

 of the Minnesota samples, crushed between steel plates, should be 

 referred to wooden cushions. Gen. Gillmore's experiments indicate 

 that granite has a greater crushing strength between steel plates 

 than between cushions of wood, amounting to eleven per cent, of 

 its strength between steel. Making such allowance, the average of 

 the Minnesota granites becomes: — 



Average strength of 20 samples of Minnesota granites, unpolished, 

 crushed between wooden cushions. 2-inch cubes. Pounds, per 2- 

 inch cube, 93,272; per square inch, 23,318. 



This result is obtained by including the strength of the samples 

 both on edge and on bed, in one calculation. 



The following table shows the same data for 20 New England 

 granites, reported by Gen. Gillmore, the most of them being on bed ^ 

 or undesignated as to whether on bed or on edge. In selecting 

 these, I have chosen the stronger of the New England granites 

 from general Gillmore's table, and in all cases except one (in which 



