66 



I cannot tell which — but there is a constant change which may 

 cause the change in thermal magnetism which is such a puzzle. 



Within a few years, the voyage of the Challenger has been 

 made, and I have little hesitation in saying it is one of the most 

 important made in the scientific history of the world. In crossing 

 those great seas, they have sounded to greater depths than ever 

 before ; and have measured, in a satisfactory way, the temperature 

 of water down to the bottom, to a depth of five miles. At those 

 depths the water is cold. There is great controversy about 

 this, whether the cold here can be formed by a stream of cold 

 water coming from the polar regions. I believe that stream has 

 some influence, but I do not believe it has enough. At the bottom 

 of the water, the ground on which the water is lying at those great 

 depths, is cold. I do not think that part partakes of the same heat 

 as other parts; that I express as my opinion, in which, of course, I 

 should be met by the disbelief of a great many persons, and I do 

 not argue it any further than that. That is the state of things as far 

 as we know regarding the present temperature of the earth ; but 

 there is evidence everywhere that there has been enormous heat 

 almost all over the earth. I will not say whether there has or has 

 not been the same heat in those which I consider the cold masses, 

 but they are so near heat that they are perforated in places that 

 come near volcanic heat ; and there are volcanic islands in all 

 parts of the oceans. There is evidence, therefore, that there is 

 heat very near the surface. In one of the bays of Italy, not a 

 great way from Naples, I have thrust my hand through the sea 

 into the sand, and found it so hot that I was glad to take my hand 

 out again. That difference of the apparent temperatures at 

 different parts, I look upon as a theory leading us to the conclusion 

 of what the earth really is. I think I have said enough of the 

 temperatures. 



Now to enter upon a matter which is undoubtedly one of the 

 boldest speculations of modern science, and the conception of a 

 very vigorous intellect. It is the formation of the Earth. I 

 cannot say its creation, but its formation, — the way in which it has 



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