THE GREAT DEEPS in 



muscles. The fish is therefore unable to go 

 down to the bottom again, but rises helplessly, 

 and more and more rapidly, until it reaches 

 the surface, usually dead, with its body greatly 

 distended, and sometimes even split open. 



VERY COLD 



The deep sea is a very cold haunt, for the 

 sun's heat is practically lost at about 150 

 fathoms ; and there is a continual sinking down 

 of cold water, rich in oxygen, from the Poles, 

 especially from the South. Throughout the 

 year there is little variation in the abyssal 

 temperature, which remains at about 28-34 

 Fahrenheit, a little on each side of the freezing- 

 point of fresh water. Eternal winter reigns. 

 There are cleverly made thermometers for 

 taking the temperature of the abysses ; thus, 

 after the well-protected thermometer has been 

 down for a while, a metal "messenger" is sent 

 spinning down the wire, which hits a spring 

 and turns the thermometer upside down, so 

 that it cannot change on the way up. In a 

 similar way water-bottles that collect samples 

 of the water at, various depths can be auto- 

 matically closed at any point. 



