On the Application of the Science of Geology to the purposes of 
Practical Navigation. By Alexander Nimmo, Civil Engineer, 
M. R. I. A. &c. 
Read October 27, 1823. 
IT is an old and perhaps a trite observation, that all the various 
branches of science are calculated to throw light upon each other ; 
and hence, that an extended acquaintance with the several depart- 
ments of natural knowledge is the surest way to attain to eminence 
in the pursuit of any one. In a society like this, composed of per- 
sons of different pursuits, and whose ideas are directed toa variety 
of objects, it is perhaps one of the greatest advantages, that, in any 
new enquiry, we may be enabled to draw from stores of information 
that are beyond the reach of any individual mind. 
Geology, it has been said, is one of the youngest of the sciences ; 
and, though much has been done, of late years, to place it on that 
sure footing of observation and induction, without which, we know, 
there can be no real progress in natural knowledge, it is yet not en- 
tirely freed from those hypothetical notions, of which the works of 
its earliest writers entirely consist. 
The modus operandi, by which the existing strata of the earth 
were first produced, or at least arranged in their present order, is 
still the favorite speculation among writers on Geology ; and, from 
the great question, whether the immediate agent has been water or 
caloric, by the presence or removal of which the particles of mine- 
rals have been arranged in their present form, there have arisen two 
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