DR. MCCLELLAND’S OBJECTION TO ARBITRARY SYSTEMS. 
203 
While we perfectly agree with our author 
that in describing a district the geologist 
I should not be bound down to any particular 
system, those of our readers who will only 
look through that splendid work, Thomson’s 
I Annals of Philosophy, and see the disputes 
i and angry feelings engendered on account of 
I rigid adherence to this and to that system, 
will bear the truthof that position. But, 
notwithstanding, system is indispensable 
to the ends of this science, which can only be 
promotedby careful observation; and hence we 
establish a system of our own. The geognosy 
of Werner has peculiar claims for admira- 
tion on this account ; void of those lofty pre- 
tensions which belong to speculations, it has 
established several principles which facili- 
tate the labours instead of obstructing the 
geologist in his researches. We also admit 
the sentiments on this subject of that cele- 
brated mineralogist, Mackenzie, that that 
system which developes the great laws of 
nature, and is substantially improved by the 
examination of her works, is of all others the 
best calculated to promote every science ; and 
accordingly we find that mineralogy has 
made the most rapid advances wherever this 
has been fairly adopted. Formerly mineralogi- 
cal enquiries produced nothing more than a 
mere catalogue of localities ; but now many 
relations of individuals have been distinctly 
determined, others are daily ascertained, and 
the most doubtful are now becoming accurate- 
ly known. 
'V 
Dr. McClelland thinks that it is best to 
follow no artificial method, such being foreign 
to the purpose of practical geognosy. He 
adverts to Werner for instance, having found 
in the mountains of Saxony, that hornblende- 
slate occurs in subordinate beds in clay- 
slate ; seldom in gneiss or in mica-slate, 
placing it in his system in consequence with 
primitive trap, assigning to it a position 
between primitive limestone and the oldest 
porphyry. In the Riesengebirge, Raumer 
found the same rock to prevail to a much 
greater extent than it had been found by 
Werner in the Ergeberg, and its geognostic 
position was found to be between granite and 
gneiss which led to Raumer’ s proposition of a 
new arrangement of mountain rocks. Now 
Dr. McClelland states that it is found in 
Kemaon, resting on gneiss, into which it 
passes on the one hand and into mica-slate 
on the other ; and from the extent and posi- 
tion our author would rank hornblende-slate 
next to gneiss among the mountain rocks 
that compose the eastern frontier of the pro- 
vince. Hence Dr. McClelland infers the ne- 
cessity of being free from the influence of 
arbitrary systems. 
Now all these differences may occur to which 
our author has alluded, and yet the influence 
of the best established system have its weight 
and importance of leading to results, which 
without system never would have been obtain- 
ed. There can be no doubt as to the mineralo- 
gical connection between the greenstone and 
the serpentine, — of the gradation between 
the two, and of the perfect character of each 
substance at the extreme points of both. As 
far as composition is concerned it is known 
that hornblende is an ingredient in both 
rocks ; but there are essential differences 
both in their chemical nature and chemical 
composition : but because of the transition 
which occurs in different spots, we do not 
argue that the systematic arrangement is 
affected to a degree to bring the geologist 
into bondage from the adoption of a system, 
as to lead him into difficulties. Dr. Mc- 
Clelland’s intelligence has communicated an 
important fact without proving that a system 
is arbitrary, but rather that all systems 
are open to improvement as wx advance 
in knowledge. Now what has been the 
effect since the days of George Agri- 
cola, the systematic mineralogist who first 
investigated the external characters of 
minerals, "who was able to determine them 
with a degree of accuracy by adopting a sys- 
tem. Cardan soon wrote a treatise improv- 
ing upon that system. Then came those by 
Becher, Bromel, Cramer, Linnaeus, Pott, 
Wallerius, Cronsted, the illustrious Werner, 
Rome, d’Lisle, Abbe, Haiiy, Kirwan, &c. each 
correcting errors and improving upon the 
system of his predecessor, so that with 
the science is system rapidly advancing 
towards perfection and is to be thus encou- 
raged. But we must hasten to conclude, lest 
Dr. McClelland’s interesting work should 
occupy more of our space than we can spare 
for a single number. We shall conclude our 
review in the next. 
