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ADDRESS. ~ Lxili 
some other large establishments of the same description, the inch is adopted 
as the unit, and all fractional parts are expressed in decimals. No difficulty 
has been experienced in habituating the workmen to the use of this method, 
and it has greatly contributed to precision of workmanship. The inch, how- 
ever, is too small a unit, and it would be advantageous to substitute the metre 
if general concurrence could be obtained. As to our thermometric scale, it 
was originally founded in error; it is also most inconvenient in division, 
and ought at once to be abandoned in favour of the Centigrade scale. The 
recognition of the metric system and of the Centigrade scale by the numerous 
men of science composing the British Association, would be a most important 
step towards effecting that universal adoption of the French standards in this 
country which sooner or later will inevitably take place; and the Association 
in its collective capacity might take the lead in this good work, by excluding 
in future all other standards from their published proceedings. 
The recent discovery of the source of the Nile by Captains Speke and 
Grant has solved a problem in geography which has been a subject of specu- 
lation from the earliest ages. It is an honour to England that this interest- 
ing discovery has been made by two of her sons, and the British Association, 
which is accustomed to value every addition to knowledge for its own sake, 
whether or not it be attended with any immediate utility, will at once appre- 
ciate the importance of the discovery and the courage and devotion by which 
it has been accomplished. The Royal Geographical Society, under the able 
presidency of Sir Roderick Murchison, was chiefly instrumental in procuring 
the organization of the expedition which has resulted in this great achieve- 
ment, and the success of the Society’s labours in connexion with this and 
other cases of African exploration shows how much good may be effected by 
associations for the promotion of scientific objects. 
The science of organic life has of late years been making great and rapid 
strides, and it is gratifying to observe that researches both in zoology and 
botany are characterized in the present day by great accuracy and elaboration. 
Investigations patiently conducted upon true inductive principles cannot fail 
eventually to elicit the hidden laws which govern the animated world. Neither 
is there any lack of bold speculation contemporaneously with this painstaking 
spirit of inquiry. The remarkable work of Mr. Darwin promulgating the 
doctrine of natural selection has produced a profound sensation. The novelty 
of this ingenious theory, the eminence of its author, and his masterly treat- 
ment of the subject have perhaps combined to excite more enthusiasm in its 
favour than is consistent with that dispassionate spirit which it is so necessary 
to preserve in the pursuit of truth. Mr. Darwin’s views have not passed 
unchallenged, and the arguments both for and against have been urged with 
great vigour by the supporters and opponents of the theory. Where good 
reasons can be shown on both sides of a question, the truth is generally to be 
found between the two extremes. In the present instance we may without 
difficulty suppose it to have been part of the great scheme of creation that 
natural selection should be permitted to determine variations amounting even 
to. specific differences where those differences were matters of degree; but 
when natural selection is adduced as a cause adequate to explain the produc- 
tion of a new organ not provided for in original creation, the hypothesis must 
appear, to common apprehensions, to be pushed beyond the limits of reasonable 
conjecture. The Darwinian theory, when fully enunciated, founds the pedi- 
gree of living nature upon the most elementary form of vitalized matter. One 
step further would carry us back, without greater violence to probability, to in- 
organic rudiments, and then we should be called upon to recognize in ourselves, 
