72 



THE MUSEUM 



safely assume that the composition of 

 abyssal sea water shows no very im- 

 portant differences from that of other 

 sea water and that the animals exist- 

 ing in it are not exposed to any pecul- 

 iar influences arising from this source 

 alone. 



This cannot be said of the physical 

 conditions. Everyone knows how op- 

 presssve to the bather is the weight of 

 the sea water at only a few feet below 

 the surface, and how difficult it is to 

 dive, still more to remain on the bot- 

 tom, if only for a few seconds 



But it is.dimcult to convey any ade- 

 quate idea of the pressure at such a 

 depth as 2,000 fathoms, or about two 

 miles below the surface. 



Rope made impervious by tarring 

 is said to have become reduced one- 

 third in its diameter by a descent into 

 these depths. Any hollow object not 

 pervious or elastic is at once crushed. 

 There is no doubt that at some points 

 on the ocean floor the pressure may 

 amount to several tons to the square 

 inch. 



If we recall that the average press- 

 ure in steam boilers is probably much 

 less than one hundred pounds to the 

 square inch it may help toward an ap- 

 preciation of the abyssal conditions. 



The inevitable conclusion is, there- 

 fore, that all the animals living under 

 these conditions must have their tis- 

 sues so constituted as to prevent the 

 free permeation of the water through 

 every part in order that the pressure 

 may be equalized. How that is pos- 

 sible without putting an end to all or- 

 ganic functions is perhaps the greatest 

 mystery of abyssal life. How can a 

 large egg, like those of various deep- 

 sea animals, pass through the stages 

 of segmentation and development, 

 with every mollecule of its structure in 

 actual contact with ordinary sea wat- 

 er and every solid particle subjected 

 to a pressure of say a thousand pounds 

 to the square inch? 



( To be eontinued. 



The Harriman Alaska Expedi- 



tion-A Small Talk About 



Glaciers. 



Chief among the objects of interest 

 in Alaska are its stupendous glaciers. 

 To more than one traveler the sight of 

 these has made real for the first time 

 all that he has read of the enormous 

 power of such rivers of ice and the in- 

 fluence that they have exerted in earth 

 sculpture. 



We are accustomed to think of the 

 world as changeless, of the hills and 

 mountains as immutable, and of earth 

 and sea as being of all things the most 

 lasting. Yet in fact we know that this 

 is not true, that all over the world 

 change is constantly taking place, that 

 volcanoes spout out lava, increasing 

 the size of mountains; that snow and 

 water and frost are constantly tearing 

 off or breaking away fragments of other 

 mountains and carrying them down to- 

 ward the plain; that the thundering 

 waves of the sea are continually break- 

 ing upon the shore, removing it in one 

 place and adding to it in another; and 

 that for the last few centuries man, 

 with his axe and his grubbing hoe and 

 his plow, is altering the face of the 

 earth, enabling the rain and the brooks 

 and the rivers t<> pick up and tarry 

 awaj the soil, which is at last trans- 

 ported to the ocean and tends to fill it 

 up. Instead of being permanent, 

 therefore, the earth which we inhabit 

 is unstable. The elements in their 

 ceaseless action, the earthquake at in- 

 tervals, and man during the short time 

 that he has inhabited it are changing 

 its surface continually. 



We know too that in very ancient 

 times the face of the land which we 

 inhabit was very different from what it 

 i now. The mountains were higher, 

 and so the valleys deeper. Great areas 

 of the land, now mountain and plain, 

 fertile farm, arid stock range, or peaks 

 only traversed by the wild animals, 

 were once the bottom of the salt sea. 

 And in the earth or the rock over which 

 we now pass are often seen the bones 

 or shells of the marine animals which 



