Penny Blood: Serial Sensation and Working-Class Entertainment — page 304: what you’re looking at

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

~ CH. XXiL] SUMMARY. 237 XVIII. Volcanic energy is the motive power on our view of compression. It will be easily seen that we reverse the sequence of cause and effect, as the subject has been sometimes regarded. The well-known theory propounded by Mr Mallet, to account for volcanic energy, makes it the result of com- pression instead of the cause. It also removes the seat of it from where we believe it to reside. We therefore feel it neces- sary to reply to his arguments. Mr Mallet based his theory upon the results of experiments in crushing cubes of rock, from which he calculated the amount of heat obtainable in that way, and concluded that the whole of the heat, that would arise from crushing one cubic foot of rock, would‘ fuse about one- tenth of a cubic foot of the same. Supposing the heat so obtained should be localized, he considered that the crushing of rock within the crust of the earth would originate volcanic action. He assumes with Hopkins, that the crust is thick, and postulates 400 miles for the thickness. We however show that the heat obtained could not be localized, but must be distributed through the crushed portion, appearing only where crushing took place, and appearing everywhere in proportion to the work done there; so that if say ten miles of the crust was crushed, it could not fuse one mile selected out of those ten. We however do not leave the question here, but go on to calculate the utmost conceivable amount of heat obtainable under Mr Mallet’s hypotheses, and find it quite inadequate for the purpose. XIX. Having cleared the ground of the fascinating, but as we believe misleading, theory of Mr Mallet, we review theories that have been propounded to account for volcanic action, on the supposition that it 1s a manifestation at the surface of the intense temperature existing below ; and that the lava and vapours, which are erupted, are brought up from an intensely hot substratum. Some of these theories require local increments of temperature, of which no explanation has been attempted; while others require the absorption of water by hot rock when applied to it externally. We believe that our theory of the constitution of the magma removes the difficulties CONNEC OOO @ (CO)