483 Encouragement of Scientific Research , [October, 
perhaps for weeks, for the desired condition. But if his 
time is not fully his own just at that moment, he may find 
himself fettered by some professional claim, and the oppor- 
tunity may slip by. 
But this is not all ; every one who has been accustomed 
to watch the operations of his own mind must agree with 
Mr. Sorby that when grappling with any difficulty, theoretical 
or practical, the solution cannot be obtained at some given 
moment, as it were, to order. The man of science seeking 
the cause of some phenomenon as yet unaccounted for, and, 
we presume, in a manner stri( 5 tly analogous ; the physician 
pondering on the origin or the meaning of some strange 
symptom ; the lawyer seeking to fill up some gap in a chain 
of argument, or the statesman considerating how some 
difficult negociation is to be carried to a successful issue — 
cannot sit down and say “Now I will solve the question.” 
The ray of light which makes all plain and intelligible often 
darts into his mind in what are called idle moments. A 
casual word uttered in conversation, some trifling fa ft 
observed by the wayside and often apparently unconnected 
with the issue, seems to fire a train, and the mountain of 
difficulty that lies across our path is shivered to pieces in a 
moment. This point is ably illustrated by Mr. Sorby from 
incidents in his own career as an investigator “ The more 
I studied the microscopical structure of these cleaved rocks 
(i.e., those possessing slaty cleavage), the more I was 
puzzled with the observed fafts. One day when quietly 
walking in my garden and reflecting on things in general, 
the simplest possible explanation of the whole flashed into 
my mind. I immediately went into my work-room, mixed 
some small pieces of coloured paper with wet pipe-clay, and 
on compressing them in the manner that slate rocks are 
proved to have been compressed, I found that I obtained a 
very good representation of the characteristic structure on 
which their cleavage depends. From that time forward the 
whole theory of cleavage took a new shape in my mind, and 
after studying by experiment with the microscope and in the 
field those fafts which this mere hypothesis indicated as 
important, in a few years I had the satisfaction of observing 
that it was universally adopted as a perfectly satisfactory 
explanation of one of the great phenomena of geology.” 
To take another case — ■“ In studying the structure of 
meteorites, the evidence of original igneous fusion becomes 
stronger and stronger, even in the case of the iron masses 
containing much olivine. This comparatively uniform dis- 
tribution of such a heavy metal as iron, and of such a 
