MOVING FOKCK. 
C31 
jf natural knowledge. These results may he studied without 
:onnecting them with any theory ; and the light which titey 
lave thrown upon the structure of the globe will continue to 
iiave good effect, whatever may be thought of the speculative 
lowers of tlie discoverer. 
Let those who are dissatisfied with this restricted praise hut like the 
remember, that in chemistry the system of Stahl, once thought Jtahn.ml La- 
mpregnable, is now almost forgotten; that even the more 
J ° ® _ L'lve place to 
refined doctrines of Lavoisier are hastening to their fall : and that, approiictang 
f the credit of a perfect geological theory be denied to Werner, discoveiics. 
he period seems not yet to have arrived when any theory of 
he earth can be successful. Negative conclusions, indeed, 
nay now be deduced, and detach id propositions may be esta- 
jlished j but before they are connected as parts of a consistent 
.vhole, our knowledge of the structure of the earth must be 
ncreased by new and large accessions of correct description ; 
■3ur acquaintance with the laws of chemistry, and of electric 
and magnetic polarity, must be much extended ; and our opi- 
iiions respecting the latter obscure but powerful agents, must 
orobably undergo a considerable change. 
II. 
On the Measure of Moving Force. By Mr, Peteu Ewart. 
{Continued from p. 97-) 
I am quite at a loss to understand why Mr. Atwood exclu- Cases of dirtl- 
Med this case from those in which the moving force may be 
(estimated by the products of the matter into the squares of their niovin^ force, 
velocities. If, in cases of rotatory motion about fixed axes, 
I'hat principle “ obtains,” as he observes, “ without exception,” 
Miere can, I think, be no exception to its application in cases 
)jf this description. 
Having gone through the examples of force producing mo- 
ion from a state of rest, we come now to the examination of 
cases 
