112 K. MALLET ON THE TEMPEEATTJRE OE THE 



10. On the Probable Temperature of the Primordial Ocean of 

 our Globe. By Eobert Mallet, Esq., P.R.S., F.G.S. (Eead 

 November 5, 1879.) 



So far as my reading has, extended, I am not aware that any author 

 on physical geology or terrestrial physics has expressed any definite 

 views as to the temperature of the primordial ocean — that is, of the 

 large body of water which, as now collected together, fills the 

 existing basin of the seas and great oceans, the configuration of 

 which, like that of the surrounding continents, has, perhaps, not 

 very largely changed during what is called geological time. Some 

 very vague and indefinite notions may, indeed, be found in the writings 

 of the early and long-since obsolete cosmogonic authors to the effect 

 that the primordial ocean was probably at some indefinite period, 

 and to some indefinite extent, warmer than the sea as existing 

 within the period of human history ; but no attempt to assign its 

 temperature at any epoch anterior to our own has, to my knowledge, 

 yet been made. ISTevertheless it seems to me that, on grounds of 

 very high probability deducible from admittedly physical laws, we 

 can approach this problem with a facility and certainty of result 

 greater than those which can be obtained in reference to many 

 physical questions smaller in extent and apparently nearer our 

 reach. 



According to the calculations of Mr. Gardner, the extent of land 

 is about 37,673,000 square British miles, leaving out of consideration 

 the Victoria continent, and that of the sea 110,849,000 square miles. 

 That this cannot be regarded as furnishing the true proportion of 

 land and water is evident, as there is still, according to Gardner, an 

 Arctic unexplored area of 7.620,000 square miles, and the Antarctic 

 unexplored surface is of vastly greater extent. 



An accurate knowledge of the mean depth of the ocean is equally 

 necessary to enable us to calculate the actual amount of water it 

 contains ; but in this respect our information is still more imperfect. 

 We know the depths revealed by certain lines of soundings, and 

 probably the greatest depths of some oceanic abysses, but nothing 

 that can give us even an approximate estimate of the cubic volume 

 even of the oceanic waters of our globe ; whilst we are in profound 

 ignorance of the amount of water permanently consolidated into ice 

 and present as fresh water in lakes and rivers. 



Previously published calculations of the total volume of water 

 existing on our terraqueous globe have been recently submitted to 

 revision by Dr. Kriimmel (' Nature,' Feb. 13, 1879), from whose 

 data I am enabled to make the following deductions. I must not 

 omit to notice, however, that there is no greater certainty in 

 Kriimmel's final results than in those previously before the world, de- 

 pendent, as they are, upon the number which he assumes for the mean 

 depth of the ocean, viz. 1877 fathoms — a number which, however 



