of Natural Philosophy. 13] 
tiate'an assertion which may perhaps be deemed harsh, 
we will just glance at the contents of the Second Book,— 
a part which certainly. affords a not unfavourable specimen 
ef the execution of the whole. As all the improvements 
which we propose are predicated on the supposition that the 
size remains unaltered, (a supposition rendered necessary 
by the limited time which can be properly devoted to this 
subject in our colleges,) we begin with the general remark 
that room might be gained for several important topics now 
_ omitted, by abridgements in the demonstrations, particular- 
ly: those i in which variations are introduced, and various oth- 
ers in which oo contributes not at all to. clearness.— 
The char percussion might have been easily made 
to include, seis its present limits, 
pact eee Bema 
ciliation of the apparently jarring theories of Newton and 
Leibnitz concerning the measure of force in coving oliek 
To that on the composition of forces, might have been ad- 
vantageously subjoined the results of impact in’ spherical 
bodies, whether non-elastic or elastic, which meet each oth- 
er from di rections not in ‘the sameright line- If the theory of 
; d at leng h inch. v. sec. 3. de- 
be retair ned, itis c only forthe s: ke fat heorem which 
7 
Bain 2t se ae oe 
determines the time of vibration. This theorem is. Valuable 
principally as it also determines the limit of the time of vi-~ 
bration of the common pendulum, when the arc is made in- 
definitely small. But as the subject is now left, not only 
is no true ee given to the student irene the 
time of vibration — circular arc, but t nace ble 
blunder of Keill, Parent, Musschenbroek — and a in 
making i it equal to n him, 
“© This isnot indeed in nso many words affirmed ; but, 
street imply | it, and become nngatory unless it is ; 
ng that vibrations in smal! mega are are perform 
theta in made from t ; oO 
the declivity of res Ero ah i twiee that of the latter. 
The accelerating force down the ar isuniform ; in the arc it isas the sine 
