Stresses in the Earth's Crust. 785 



the above minima. But as the preparation of pure crystal- 

 lized albumins was not known in Graham's day, it is necessary 

 that his diffusion experiments should be repeated with various 

 pure albumins and with their products of disintegration, such 

 as peptones, if we are to arrive at accurate estimates of the 

 size of albumin molecules and their parts. 

 Melbourne, March 1905. 



LXXVL On the Stresses in tJie Earth's Crust before and after 

 the Sinking of a Bore-hole. Btj 0. Chree, Sc.D., LLJJ., 

 F.R.S* 



Contents. 

 § 1. Introduction. 

 '2. Tendency to rupture, 

 o. Notation. 



4. Homogeneous isotropic gravitating sphere. 



5. Composite gravitating sphere, crust, and nucleus. 



6. Spheroidal rotating " Earth." 



7. Solid vertical prism under gravity and pressure. 



8. Hollow vertical cylinder under gravity and pressure. 



9. Solid prism under pressure. 



10. Hollow cyliuder under pressure. 



11. Solid sphere under pressure. 



12. Hollow sphere under pressure. 



13. Normal stress on small area of infinite plane. 

 14-20. Applications to the Earth. 



§ 1. TN 'Nature/ October 20, 1904, p. 602, there appeared 

 A letters by Mr. G. Martin and the Hon. 0. A. 

 Parsons dealing with the size of the stresses in the Earth's 

 crust and speculating as to what would happen if a hole were 

 bored to a depth of twelve miles. 



The letters indicate that some interest attaches to the 

 problem, but its true character seems to stand in need of care- 

 ful consideration. We know at present so little of the nature of 

 the earth's material, even at such small depths jis twelve miles, 

 and have such scanty knowledge of the combined effects of 

 high temperature and high pressure, that there are no data 

 for making an exact calculation. Rocks as we know them 

 at the earth's surface are not isotropic or even homogeneous 

 solids, and they are not perfectly elastic for any considerable 

 -est; but the crust of the earth seems to behave as a 

 solid so far as can be inferred from earthquake-waves, and 

 nothing that is positively known forbids the hypothesis that 

 the material a few miles down is elastic for moderate changes 



* Co mmunica ted bj the Physical Society: read March 10, I9Q». 

 + Japanese Kartl)quak<,' [hvestigatloD Committee, Reports No. 17. 



