Penny Blood: Serial Sensation and Working-Class Entertainment — page 86: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

cH. vr.} HYPOTHESIS OF SOLIDITY. 69 the depth 2a. But no account has been taken of the corruga- tions. which would arise from the compression of this portion itself. However Sir W. Thomson concludes that below the depth of 100 miles the earth will be at the proper melting temperature for the pressure, whilst 24 = 160 miles. Conse- quently our assumption on the first account makes the effect of the cooling of this portion of the sphere enormously too great, - whilst on the second account it is made somewhat too small. If we take half the calculated effect we may feel certain that we have taken it large enough. We will therefore put this term at 94 feet. The first two terms of the bracket multiplied by = give 58 feet. And half the third gives 5 feet, and is negative. On the whole, therefore, we may conclude that ke = 286 +94 + 53 feet, = 433 feet. And 2ke = 866 feet ; a result which is probably considerably too large, In other words, if all the elevations which would be pro- duced by compression, through the contraction of the earth cooling as a solid upon the above suppositions, were levelled down, they would form a coating over the whole globe of about 800 feet in thickness. This is an exceedingly small result. We will now enquire how the result of our calculation will be affected by assuming a different value for the melting tem- perature, about which we have no very certain knowledge. Di The function 2 [" ede, by which Sir William Thomson hes 0 expressed the temperature within the earth at the depth a, requires that the law of its increase shall not be affected by the sphericity of the surface; which he has shown under the circumstances to be an admissible supposition. This assump- tion 1s therefore involved in our value for Pn; and it evidently GONG oOo SS (CO)