367 
seem to us to have failed truly to study the subject of force. 
This cannot but prove a defect of great influence, and such as 
might be expected to produce results of the most disastrous 
character to the science. In these rocks, observed by Mr. 
Geikie in the very process of change from sedimentary sand 
and mud into what were imagined to be fused masses slowly 
cooled down and crystallized under pressure, but which are now 
seen to be simply changed masses becoming trap and granite 
before the observer's eyes, the very chief of geologists seem 
not to have even the ghost of an idea as to the power which is 
effecting the change. Take, for example, a piece of the un- 
doubtedly aqueous rock before it has become changed, and a 
piece of the trap into which it has been changed; — here are two 
“ facts," and what is the relation of the one to the other ? The 
one kind of rock has passed into the other ; — but how has the 
change been effected ? Geology cannot tell. Why so ? Because 
a force is at work which has been ignored. It has been thought 
of only by “ heretics " ! 
In explaining the present mineral constitution of the varied 
strata, there are still, as we have said, only two great agencies 
recognized in any adequate degree. These are fire and water. 
Igneous and aqueous influences are the only ones that are 
allowed prominently to occupy the mind, while the best 
writers describe what is believed to be the origin of rocks 
as they now appear in the earth. The wearing down of 
strata, with the consequent formation of sedimentary beds 
by means of water, and the alteration of these sedimentary 
strata, by heat, under great pressure, seem to have filled the 
scientific mind, as if almost no other forces existed in nature. 
Playfair speaks decisively on this point. He says, “ In Dr. 
Hutton's system water is first employed to deposit and arrange, 
and then fire to consolidate, mineralize, and lastly to elevate 
the strata ; but with respect to the unstratified or crystallized 
substances, the action of fire only is recognized."* Hutton has 
been followed with wonderful docility by most of our popular 
geologists. Hence fire and water are still the only great 
acknowledged forces. Chemical changes, so far as they are 
aqueous, that is, so far as they occur through water, are 
recognized. The electrical force, which is surely more 
than equal to heat, on the one hand, and to all aqueous 
forces on the other — more than equal indeed to both 
combined — - seems lost sight of. I should think that it 
will readily be admitted that the altering powei of the 
electric current is greater than that of either heat or 
* Playfair’s Illustrations, p. 131 . 
