370 Mr A. J. Adie on the Expansion of Stone 



this gradual increase in the length of the rod ; and by the effect 

 of the two heatings noted after I observed it, the rod was length- 

 ened .0096, or nearly the hundredth of an inch. On the rod of 

 Carrara marble, the elongation took place mostly at the first heat- 

 ing, and it amounted to .0135 of an inch. This may probably 

 serve to account for the warping which sometimes takes place on 

 those parts of chimney-pieces which are subjected to the greatest 

 action of the fire. It is impossible to say how far this lengthen- 

 ing would be increased by a greater change of temperature ; but, 

 since Mr Bab b age has applied the expansion of stone to the ex- 

 planation of geological phenomena, this property of limestone 

 may also be taken into account, as it only requires the heat to 

 have been once in action after the strata have been formed. In 

 the experiment on the rod of Carrara marble, the whole effect 

 was produced by an increase of temperature of 157° F. ; and 

 if we suppose this to have acted on strata five miles deep, the 

 depth taken by Mr Bab b age, in accounting for the changes 

 of the level of the Temple of Serapis, the surface would have been 

 raised by not less than 15|- feet. Little weight, however, can be 

 attached to such explanations of the great operations of nature, 

 as there may be a vast difference between the effect of heat 

 quickly communicated to the small pieces of stone on which we 

 perform our experiments, and the necessarily slow diffusion of 

 the heat through such a depth of strata as we have supposed. 



In order to ascertain if there was any connexion between the 

 density of stones of the same composition and their expansibility, 

 as takes place with the metals, I determined the specific gravity 

 of several of the rods, but the one property does not appear to 

 have the least dependence on the other. For instance, the spe- 

 cific gravity of Sicilian white marble and Galway black marble 

 is 2.7127 and 2.7093, almost exactly alike ; the expansion for 

 180° F. of the former is .0325392, while that of the latter is 

 only .0102394, not one-third of the first. In determining the 



