THE WORLD BEYOND OUR SENSES' 



Shut out from our apprehension of what is going 

 on around us by all but a narrow peep-hole, as it 

 were, we find, as we turn, that we are equally limited 

 in every other direction. Particularly notable is 

 this when we consider the phenomena due to that 

 especial mode of motion we call heat. 



Water at freezing gives us the sensation of in- 

 tense cold; at boiling, of intense warmth. To 

 measure the gradation of warmth, or cold, between, 

 \vc find a substance which expands evenly, like 

 mercury, and, taking a tube, mark the point at 

 which the mercury stands when placed in freezing 

 water as zero, and the point to which it rises in 

 boiling water as 100 degrees. We have then the 

 centigrade, or " hundred degree," scale. This scale 

 is in universal use throughout the world, save in 

 two backward countries called England and the 

 United States. Within the limits of the centigrade 

 scale by far the greater part of terrestrial events 

 take place. For example, above or below this 

 scale, life, in any active sense, is impossible. But 

 artificial resources enable us to go far below the 

 freezing-point of water, and the gas-flame, the grate 

 fire, or the electric arc supply temperatures far 

 above boiling. And we know that space is far cold- 

 er, and the interior of the sun far hotter, than any- 

 thing we can attain here. 



Under sufficient pressure, when we reach about 

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