ek 
on the Steam Engine. 323 
struction; none is so likely to discover new methods of improvement. 
Before we cam control the powers of nature, we must learn their laws 
or modes of action; and our dominion over them can be commensu-— 
rate only with a knowledge of their properties. By studying the prop- 
erties of flame, and especially of that which results from the combus- 
tion of the mixed gases extricated in coal mines, Davy was led by a 
short and easy route to the discovery of the safety lamp; and it was 
by learning the properties of the electric fluid, that Franklin subject- 
ed to his control the lightning itself. b 
Professor Renwick, we are happy to say, possesses in an eminent 
degree the qualifications to which we have alluded. Well versed in 
both mechanical and chemical philosophy, he is qualified to expound 
the various scientific principles that are necessary to be understood, in 
order toa complete knowledge of the construction of the Engine, or 
of the nature of the dangers which attend it, while his situation at 
the fountain-head of steam navigation, and his extensive intercourse _ 
with manufacturers of steam engines, and the most successful build- 
ers of steam boats, afford him great facilities for becoming intimately 
acquainted with the, practical part of his subject.. Under these fa- 
Yorable impressions of the author, we took up the work before us 
With the expectation of being highly gratified and instructed; and 
We are happy to add, that the perusal has not at all disappointed us. 
We can therefore cordially recommend this Treatise, as a work which 
_ Contains an able and succinct account of the Steain Engine in its va~ 
nous forms, presenting a perspicuous view of this great subject in its 
Multiplied relations, as it regards its construction, the means of insur- 
ing its safety, its applications, and its history. ; 
- Under the head of “Mechanical and Physical Principles,” with 
which the work commences, we are presented with a concise but lu~- 
Minous view of those principles of mechanics, and those laws of 
heat, which relate to the Steam Engine. This part of the work is 
Well adapted to a numerous class of readers, embracing a large pro- 
Portion of the ‘practical men for whom the Treatise was designed, 
Who have not had. an opportunity to. acquire this knowledge in the 
regular course of education; and to many who had once acquired 
the same information, it will serve-as a useful review, and nothing 
will contribute more to a clear and intelligent acquaintance with the 
Whole doctrine of the Steam Engine, and with all the discussions that 
arise respecting the sources of its dangers and their proper remedies, 
than a fresh and familiar knowledge of these elementary principles. 
