404 SKETCHES OF V BE ATI OK. 



the sun ; while, according to Fourier's celebrated computa- 

 tion, the heat radiated from the earth's surface is only suf- 

 ficient to melt a layer of ice ten feet thick in one hundred 

 years. 



The most conservative of these results may be regarded 

 as showing that our earth is actually losing heat to a per- 

 ceptible and measurable extent. Neither is the amount 

 of heat escaping at Paris to be taken as the measure of the 

 reduction of the temperature of the mass of the earth in 

 general. There are three hundred active volcanoes in ex- 

 istence, from the craters of which enormous quantities of 

 heat are permitted to waste. The ocean, too, carries off 

 vastly larger quantities than the land. The floor of the 

 ocean is generally overlaid by a stratum of ice-cold water 

 setting southward from the polar regions. This cold stream 

 is overlaid by a warmer one moving northward from the 

 tropics. Water being a better conductor of heat than at- 

 mospheric air, this cold stratum must necessarily abstract 

 terrestrial heat with vastly greater rapidity than the aver- 

 age atmosphere of the temperate zone. Many observations 

 indicate that the temperature of the solid crust beneath the 

 waters of the ocean is much higher than that of continent- 

 al surfaces, and hence imparts its warmth in larger quan- 

 tities. Throughout all that part of the Frozen Ocean north 

 of Europe and Asia, the temperature is found to increase 

 at considerable depths, contrary to the well-known laws of 

 hydrostatics. [See Appendix, Note X.] The same phe- 

 nomenon has been observed on the coast of Australia, in 

 the Adriatic, and Lago Maggiore. Horner asserts that in 

 the deep soundings of the Gulf Stream, off the coast of the 

 United States, the lead, when drawn up, " used to be hotter 

 than boiling water." 



These facts, with others, seem to demonstrate that our 

 planet is wasting its warmth many times faster than the 



