428 



EEPORT — 1886. 



The value c can be obtained from photographs or drawings of a 

 mountain, while r may be obtained from pendulum experiments or 

 from specimens of volcanic material. With these data we can determine 

 the modulus of resistance for the elastic limit of the materials which com- 

 pose a mountain on a large scale, for many constituents of the earth's crust. 



Mr. Becker concludes his observations by remarking that a study of 

 the form and dimensions of lunar volcanoes would lead to values of j, 

 whence we might approximately determine whether the lunar lava is 

 similar to that of terrestrial origin. 



In the following table I have followed out Mr. Becker's suggestion 

 and calculated ' the modulus of resistance to crushing at the elastic limit 

 in lbs. per square foot for a number of Japanese mountains.'' The different 

 values for — for the same mountain are in great measure due to my not 

 being able to obtain an accurate scale for the various photographs which 

 had to be investigated. Another difficulty was obtaining a value for r or 

 the density of the mountain. Professor T. C. Mendenhall, who made a 

 number of experiments with pendulums on the summit of Fujiyama, 

 says the rocks of that mountain have a density of 1.75. This is when 

 they have air in their pores. As powder, the density becomes 2.5. Wada 

 gives the specific gravity of the rock on Fujisan as 2.6. Assuming the 

 density of the earth at 5.67 (Bailey) then the density of Fujisan, as de- 

 termined by Professor Mendenhall's experiments, is 2.08. In my calcu- 

 lations for the following table I have assumed a density of 2.5 for the 

 materials of all the mountains mentioned. 



Comparing the results given in the above table with the numbers in 

 the following table, which are based on experiments referred to in Ran- 



2 k 

 ' It will be noticed that there is difficulty in defining the quantity — as caleu- 



r ' 

 latedfrom the shape of a mountain. It is assumed that the materials are not crushed. 

 ' This is the height above Lake Chuzenji. 



