MECHANICAL STATE OF THE ISOSTATIC SHELL 



257 



"In the case of the granite the holes when filled are closed by what appear 

 to be minute fragments of granite detached from the walls. In the case of 

 experiment 358, after the removal of the steel the vertical hole as seen from 

 either end was still open and was unaltered in size or shape for a distance of 

 .08 and .24 inch respectively. Beyond tliat, however, it was blocked up. On 

 removing the steel so as to expose the extremities of the transverse hole, it 

 was found that one end of this hole was completely filled up, no trace of the 

 opening remaining. The locus of the hole was occupied by what seemed to be 

 part of the rock, finer in grain than the rest and which looks as if it were a 



os'/fo/e o^cenfre. 



m^lStee:CylM<i.r l ^ \^^^ sM%/s&» . 



Figure 2, 



-Diagram showing the Column of Rock with a vertical and transverse Hole 

 drilled through it, inclosed in a heavy Tube of nickel Steel 



perfectly compacted mass of powdered granite. The other extremity of the 

 hole had also been completely closed, although an outline marking its original 

 position could be seen ; it was filled with finely granular material, clearly 

 crushed granite, imbedded in which were a few relatively larger fragments, 

 giving to the whole the appearance of a breccia." 



In experiment 358 the pressure on the granite amounted to 222,500 

 pounds to the square inch, and thus corresponded to a depth of 35 miles 

 in the earth. In experiment 357 the pressure was 200,000 pounds to the 

 square inch, or 31 miles depth, and only the vertical hole was partly 



