374 On the pretended Parallel’ Roads of Glen Roy. 
But bodies generally, or always, attract different proportions 
of the ethereal fluids; and ali chemical attractions, it 1s probable, 
diminish in force towards each particle, as the number of those 
particles increase; while the attraction which other bodies have 
for the ethereal fluids, at all times operates to regulate the acting 
force of their attraction in the combining substances. The sim= 
ple effect above described must always be very materially modi- 
fied by these circumstances, as well as by the degree of attraction 
which the bases have for each other; not, however, so as to ren- 
der particular proportions of no consequence, but, probably, so as 
to occasion several specific proportions, in which the substances 
would be disposed to enter into combination with different de- 
grees of intensity. 
If, however, the attraction between the bases should be very 
small in comparison with that which each of them might have for 
the ethereal fluid combined with itself, it is probable that the 
only way in which their attractions for each other would act, 
would be as compound particles, formed of each base and the 
ethereal fluids in combination with it. And when, from cireum- 
stances, this very weak attraction could operate with effect, they 
would probably unite in every proportion. This probably may 
be the explanation of the mode of combination of fluids, and of 
the solution of some solids, which may be mingled and diffused 
through each other in all quantities. © 
LXI. On the pretended Parallel Roads of Glen Roy. By 
A CoRRESPONDENT, 
To Mr. Tilloch, 
Sir, — I AM an enthusiastic admirer of geological researches, 
although a mere novice in the application of its curious and eom- 
plicated principles to practice in the field; and having lately read 
in Vol. LV. of the Geological Transactions, Dr. MacCulloch’s 
very elaborate account of Glen Roy, Glen Gloy, and others in, 
the vicinity of Fort William in the Highlands of Seotland; I was 
anxious to learn without delay, the opinion of a mineral surveyor 
of some eminence, with whom I am acquainted, as to the suffi- 
ciency of the explanation offered of this singular phenomenon by 
Dr. MaeCulloch, whose paper I found he had read ; when the reply 
of my friend was, ‘* The pretended parallel roads of Glen Roy 
are the edges of horizontal strata, and were not occasioned 
either by the labour of man or the action of the-surface of wa- 
ter, as has been supposed.” He went on to explain to me, that 
such tracts of perfectly /evel strata, at any considerable elevation 
above the present sea, as he believed to exist around Glen Roy, 
were 
