Clarence King — Age of the Earth. 



Table No. 5. 



Estimated Melting Point and Depth for the rock Diabase expressed in radial earth 

 distance, pressure and melting temperature. 



m . n. 



Earth Rad. 

 •920 



n. 

 Earth Rad. 



000 

 995 

 990 

 985 

 980 

 960 

 940 



Atm. 







8600 

 17400 

 26400 

 35600 

 74500 

 116400 



° 0. 



1170 



1380 



1600 



1830 



2060 



3030 



4080 



p. 

 Atm. 



•900 



•8 



•6 



•4 



•2 



•0 



162000 

 199000 

 497000 

 1260000 

 2100000 

 2770000 

 3020000 



6 . 



m 



°0. 

 5210 

 6100 

 14000 

 33000 

 54000 

 71000 

 76000 



Table 5 contains a prolongation of Barus's line of melting 

 point and depth for the rock diabase, expressed in radial earth 

 distance n, pressure p (Laplace's densities), and melting tem- 

 peratures, d m . 



The Chart. 



The chart constituting Plate II is constructed to present the 

 passage of certain hypothetical temperature gradients through 

 the uppermost - 08 of the earth's radius, and the position in the 

 same field of Barus's line marking the melting point in depth of 

 diabase, thus defining the relations of the various distributions 

 of earth-temperature to liquidity. The value of the ordinates is 

 each one thousand degrees Centigrade ; the abscissae, which are 

 platted as equal in length to the ordinates, represent hun- 

 dredths of radius counting downwards from the surface which 

 is indicated by the right vertical boundary of the chart. 



Kelvin's application of the Fourier equation involves an 

 assumed initial excess of temperature, an assigned value of rock 

 conductivity, a given period of secular cooling and the sur- 

 face rate of augmentation of earth-temperature. As thus 

 applied to the case of the cooling earth, it is obvious that 

 while the body was of uniform initial heat there would 

 be no augmentation of temperature from the surface down- 

 ward, or otherwise expressed, the surface rate would be go ; 

 but the moment refrigeration began a finite rate of downward 

 increment would be established. Since the earth's surface is 

 represented on the chart by the right vertical boundary, that 

 line would be the thermal distribution'for the rate go. A com- 

 plete process of refrigeration would cause the rate to decline 

 until the earth reaches the temperature of space and the 

 line of initial tangency coincides with radius, and the rate 

 0. The angular relation of the initial tangent of the present as 

 compared with that of the rate go is determined from ob- 

 served surface augmentation. 



