258 GEOLOGY OF THE SECOND DISTRICT. 



All these bars were then carefully gauged, both in breadth and thickness, at every inch of 

 their lengths, before commencing the trials of tenacity. The machine employed in testing 

 them was the same which had been used in experiments made at the request of the Treasury 

 Department, on the strength of materials for steam boilers, for a description of which the 

 reader may be referred to the report on that subject.* The following table will be understood, 

 without any other remark, than that the breaking weights in the fifth column are corrected for 

 friction of the machine. The specific gravities of several of the fragments of each bar, after 

 it iiad been broken up, are given under the head of observations, and may serve as well to 

 illustrate the general character of the iron in this respect, as to indicate the effect of the several 

 methods of preparation on the density of iron. 



The following experiments confirm the evidence already adduced of the great toughness and 

 ductility of this variety of iron. Besides the facts mentioned under the head of observations 

 in the seventh column, we may add, that after the first fracture on each bar, a measurement 

 was taken between two of the inch marks still remaining on one of its parts, and the following 

 results obtained, viz : 



No. I. In an original length of 6 inches, had been elongated -87 inches = 14 -5 per cent. 



II 4 " 0-2 " = 1-5 « 



III 5 " 0-6 " = 12-0 " 



IV 4 " ........ 0-2 " = 5-0 " 



* See also Journal of the Franklin Institute, Vol. 19, p. 84. 



