The spirit of the age. [volume] (Woodstock, Vt.) 1840-1844, 1841-10-22

ny the amount OF space through which 1t Will rals
a definite weight in definite time. If then tn
power which steam engine exerts during any give
time be thus determined it will be evident tina
if the the time be doubled, so will also the powe
expended; and if the time and velocity be b.t
doubled, then will the power be quadrupled.
Now let us apply this same rule to the measur
ing of the reserved power or momentum Off bod,
in molon.-A velocity of 32 feet per second, o.
the momentum consequent on such velocity, will
elevate body l6 feet at an average velocity o
l6; and velocity of 81 will elevate the same bod,
GA feet, at an average velocity of 80. Hence the
velocity and time being both doubled, there will
be quadruple power expended, which is equal to
the reserved power, which is equal TO the momen-
tum.
| But the learned Professor, in his second obiec-
ton, very wisely informs us that time ought TO be
regarded in the measurement of forces. Now |
shall be much obliged to him, if he will show by
arguments based on correct view of the subject,
bu, not on history, wherein, either in these remarks
or the communication submitted TO him, time has
not been duly regarded.
| 1t will be seen that the definition of the term
momentum which | have adopted, is borrowed
from or at least corresponds with the usual dcfni-
ton. If then, as really believe, there is no DIFF
ference Of opinion as to what is meant by momea-
tum the only disagreement will be found in the
methods of measuring it, But why, ask, should
a rule perfectly simple and easily comprehcnded,
be adopted in measuring the power of an animal
or water or steam, and another rule leading 10
different conclusions, be adopted in measuring mo-
menium, which is the force, which is the reserved
power of body in molioa' Is power in the one
case different thing from power in the olher'
But it seems tha, in some of the experiments
adduccd, the method of measuring momentum is
agreed upon. And the advocates of error to be
consistent, assert, falsely, that if Il body A, whose
quantity is lbs. be projected with velocity Of
80 against body b, whose quantity is h., so
as to transfer the momentum from A TO b, leaving
at rest. then will b be put in motion at u vco-
city OF 81. Now the velocity GA, of B, will ee-
yale it Ga feet, whereas the velocity 80 of A, will
elevate it only IS feet. Now who does not know
that the elevation of ID. 32 feet, requires the
same power as does the elevation Of 2 lbs 10 feet;
hence if the above assertion were true all the
power expended in elevaing B, through the addi-
lona 80 feet,s unaccrcdited, is gained, is stolen
from nature. lie who made this discovery should
have secured the benefits Of it by letters patent for
on this principle, an accumulation Of power 10 an
limltable extent might be acquired
The learned Professor speaks of my objections,
that they have been removed, &c. regret that
he did not discover that stated facts rather than
objections, and that my deductions, being princi-
palIy mathematical, if they were false, might be
easily shown to be so.
1t was limited by an author who treated of this
controversy, that it appeared that there might be
two kinds of momentum. Now have defined one
kind, easily comprehendcd, and perfectly appIica-
BILE TO every case of bodies in motion. Pray what
Is the other kind There is none.
The attention of mechanics and mathematician
is respectfully invited to this subject. Any person
whose attention may be directed to this subject,
will confer favor, by directing line 10 the sub
sc,iber, giving his views and opinions
Ms sincere thanks are due to the publishers of
the journal, to winch the following communication
was directed, for the polite attention with which ii
was received. And while eXonerate the pub
fishers from all responsibility for the injustice which
| have received, am also willing TO believe that
this injustice has arisen from opinions founded on
preconceplions rather than from a candid review
and examination Of the subject.
]. b. HARTWELL.
Woodstock, Oct 10, 1871.
Here follows the communication referred TO:
UoodSiock, May 81, lSil.
To the Publishers Of -.
The object Of this communication is to call at
ten,ion 10 some supposed errors which are found
| in most IF our elementary bonks m phys or