‘principles, or in other words, that he begin with practice 
oe in theory, This is the very order of nature, for 
our first notices of things, are simple, and practical, and we 
then proceed to enquire into their foundation, and the causes 
of their phenomena, 
The second Vol]. of our author’s very extensive work on 
mechanics is occupied altogether with what may be denom- 
inated practical mechamics; this not only applies to prac- 
tice, some of the important theories of the first volume, but 
goes very extensively into the description by language and 
drawing, of almost every machine, engine, or mechanical 
work of ingenuity, which as yet, has resulted from the exer- 
ercise of the human faculties in this branch of science. 
This portion of the work, will, we believe, be by far the 
most acceptable to the real mechanician, as that of the first 
volume can only be so for the most part, to profound math- 
ematicians, or,men of rare genius, and acquirements, 
We will conclude our remarks, which we fear, have: al- 
ready been extended too far into details, with a concise 
opinion of the merit and importance, which may justly be 
attributed to this work asa whole, embracing a mass of sci- 
entific materi n this respect, we consider it as the 
the ] - Though the theoretical part has 
been studiously rendered abstruse and difficult to beginners, 
by the overweaning attachment of the author for analytics, 
and sometimes for metaphysical discussions, there is besides 
an abundant supply of useful theory, illustrated in a plain 
entary style and method. No reader can be at a loss 
work, he will have little else to search for, to obtain all the 
scoveries, and improvements, which have been made in 
this science. 
RS aR EI a Shah hee eo 
Ant. XI.—On the form of the teeth of Cog-Wheels; b 
ee Eu: W. Buaxe, A. Ms Neletiote, : ; 
It is very important in most kinds of Wheel Work that 
such a form should be given to the acting faces of the teeth 
