BABBAGE ON THE TEMPLE OF SERAPIS. 211 



92. Another consequence of this constant change in the position 

 of the isothermal surfaces must be the development of thermo-elec- 

 tricity, which, acting on an immense scale, may determine the melt- 

 ing of some beds, or the combination of the melted masses of others, 

 or cause the segregation of veins and crystals, in heated though not 

 fluid portions of the strata exposed to its influence. Nor may the 

 dykes themselves be without their use, either in keeping up the 

 communication for the passage of electricity, if they are good con- 

 ductors ; or in separating the groups of strata which produce it, if 

 they are bad conductors. 



93. It is by no means necessary that these fused strata should be 

 connected by dykes or other means with any cauldron of melted 

 matter below ; nor even that any large portion of the interior of the 

 earth should be in a melted state. The mere advance of the iso- 

 thermal surfaces may cause some more readily fusible strata to melt 

 between its two adjacent more refractory companions. Two beds 

 even — such, for example, as compact fluor and sulphate of lime — 

 may each, when separated by intervening beds, have been submitted, 

 by the passage of a highly heated isothermal surface, to intense heat 

 without fusion : yet two exactly similar beds occurring higher up 

 in the series, and perhaps not submitted to the same intense heat, 

 may, if placed in immediate contact, by acting on each other as 

 fluxes, become for ages a liquid fiery ocean, intercalated between 

 strata regularly deposited from water. 



94. The eff'ects of this fusion of some intermediate strata may 

 also be to alter the surface and dislocate all the beds above. If the 

 matter expand by fusion, then elevations and cracks will ensue : if 

 it contract into smaller compass on melting, then subsidences will 

 occur ; and in both cases, when a large extent of the earth's sur- 

 face rests on a fluid bed contained in an irregular cavity, we may ex- 

 pect, from the difl"erence of the weight above it at different points, 

 that a system of irregular elevations and depressions will continue 

 for a time to occur, until the conditions of equilibrium are fulfilled 

 between the superincumbent weight and the fluid or semi-fluid and 

 viscous mass. 



This process will require time for its completion, and when ac- 

 complished, the surface above will remain undisturbed for ages. 



It appears also that in case the intervening melted strata contract, 

 the surface of the country above may be influenced by two or more 

 causes. First, by the general elevation arising from the expansion 

 of all the solid strata by heat, arising from the advance of the 

 isothermal surface towards the surface of the earth. Secondly, by 

 the depression arising from the melting of one or more of the inter- 

 mediate beds. The joint action of these causes may produce many 

 successive alternations of elevation and depression in the same por- 

 tion of the earth's surface. 



95. For the elucidation of this subject, it appears very important 

 that experiments should be made on the effects of long-continued 

 artificial heat in altering and obliterating the traces of organic re- 

 mains existing in known rocks. It seems probable that, by a well- 



