THE GREAT DEEPS 109 



could throw Mount Everest into this " deep," 

 the mountain would be swallowed up, with 

 2600 feet to spare. The " Swire deep," off 

 Mindanoa, is actually a little over 6 miles in 

 depth. 



GREAT PRESSURE 



In deep water there is necessarily great 

 pressure, because of the immense weight of 

 water. At 2500 fathoms it is 2^> tons on the 

 square inch an unendurable pressure, if it 

 were felt. It is twenty-five times greater than 

 the pressure exerted by the steam on the pis- 

 ton of our best railway locomotives. The 

 general reason why the pressure is not felt is 

 that the bodies and tissues of the animals are 

 permeated by the water. If a ship's hawser 

 is sunk to a great depth, it is squeezed to less 

 than the diameter of one's wrist. If a piece 

 of wood is weighted and sunk to a great 

 depth, it is so much compressed that it will 

 no longer float when brought to the sur- 

 face again. But if a delicate glass vessel with 

 holes all over be lowered it is not broken, for 

 the water goes through and through it. In a 

 general way, this is true of the deep-sea ani- 

 mals. But this is not the whole truth. 



