The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913, 1895-09-01
KINETIC STABILITY.
BY ROBERT STEVENSON, C.E.
FIFTH PAPER.

your Bible and read the Book of Proverbs
through carefully three times, and if after
that you have not discovered eternal life,
then thou art dead whilst thou Eveth.
This difference between momentum and
kinetic energy is really a very simple mat
ter. In mathematics it is only the differ
ence between and w !; but, as you have
seen, it is the difference between death and
| life, both in the inorganic, the organic and
the spiritual divisions of nature; and it is
difference which science does not yet
realize.
And as it is necessary that every reader
who wishes to follow the demonstration Of
the cause of gravity should fully under
stand that difference, have taken partic-
ular pains and q great deal of space to
make my meaning simple and clear, but
now l must proceed.
First, then, science teaches that the
earth and the other planets of the solar
system are constrained to move in orbits
by the centrifugal force of the suns attrac-
ton.
Hear what Newton says about that CEN
trifugal force in Definition V, Book l, of
the .'Principia":
ga centrifugal force is that by which
bodies are drawn or impelled, or any way
tend toward point as to center; of this
sort is gravity, by which bodies tend to
|
which iron tends to the loadstone; and
that force. whatever it is, by which the
planets are perpetually drawn aside from
| the rectilinear motions which otherwise
they would pursue; and made to revolve
| in curvilinear orbits. A stone whjrled
about in sling endeavors to recede from
the hand that turns it, and by that
endeavor distends the sling, and that with
SO much the greater force as it is revolved
with the greater velocity, and as soon as
ever it is let go flies away; that force which
opposes itself to this endeavor, and by
which the sling perpetually draws back the
stone toward the hand, and retains it in its
orbit, because it is directed to the hand as
the center of the orbit, / call the centri-
petal force
Those who wish to follow this most in
teresting subject through all it's mathemat-
ical phases cannot do better than study the
principal" of Newton, and the "Mecan-
| ique Celeste Of La Place.
But it is sufficient for the general reader
orbital motion round the sun IN the same
way as it explains the centrifugal force of a
stone swung round the hand at the end of
a string the tension or stress of the string
is required to keep the stone revolving in
a circle, and in the same way there is a
tension or stress between the sun and the
earth, to keep it revolving round the
posed by some scientists to be a property
of matter, in the same way as magnetic
attraction was supposed to be a property
Of the loadstone, and at one time it was
supposed to act through vacuum and
was called action at a distance. But since
| Faraday discovered that magnetic attrac-
| ton was not action at distance, but was
caused by lines of force in an elastic me-
dunn, the greatest scientific authori-
ties of the present day have come
to the same conclusion with respect to gray
itation, and they ascribe the apparent at
traction of matter to lines of force, acting
through or by an elastic medium which
pervades all space, and the interstices of
all bodies; but as the conditions of the
problem are such as to require medium
100 times denser than steel, and yet having
as little resistance to body moving
through it as vacuum, the greatest author
tiles have not yet succeeded in finding that
medium. They are yet at sea with respect
to the true cause.
great scientists who, during the last hun
| dred years, have devoted more than one
| half of their whole lifetime of study to the
solution of this great problem, in the
vain endeavor to find medium per-
vading all space 100 times more rigid
than steel, and offering no more re-
sistapce to matter than q vacuum,
ity, the simplest thing in all creation, is
the true cause, we feel humbled with awe
and amaZement to think that such SIM
pie truth should be hidden from the wise
and the great and revealed unto babes.
The conditions of the problem, as given
out by the Smithsonian Institution to those
who wish to solve it, are:
at is well to bear in mind that every
hypothesis directed to the exploitation of
gravity is required in limine to give salts
factory account of the phenomena as given
in the following six characteristics of this
mysterious influence.
"First-Its direction is radial toward the
acting mass, or rectilinear, indefinitely.
This rectilinear traction is incapable of de-
Election by any intermediate force. 1t suf-
fers neither disturbance nor interference
from any multiplication of similar lines of
action, and admits neither of reflection, re-
fraction nor of composition.
"Second-Its quantity is exactly proper
tional to the acting mass-ind efnitely.
Corollary: hence, second, its integrity of
action is complete with every accumula-
ton of additional demand-indefinitel
that is to say, no multiplication of duty in
the slightest degree impairs its previous
tensions.
'Third-Its intensity is diminished by
recession in proportion to the square
analogous to-but as modified by the Sec
ond condition radically different from
the action of light.
Fourth-Its time of action is instanta-
neous throughout all ascertained dis
tances, and, therefore, presumably
indefinitely. Corollary: hence, fourth lb),
its rate of action Cf the expression
may be tolerated) is precisely the
same on all bodies at all velocities-indefi-
nitely. 1t no more lags on comet ap-
preaching the sun at tho lnconceivable
speed of 200 miles in second than on a
body at the lowest rate of motion, or than
on the same comet receding from the sun
at the same velocity.
''Fifth-Its quality is invariable under all
circumstances indefinitely. 1t is entirely
unaffected by the interposition of any ma
terial screen whatever, its character or ex-
tent, or, in other words, it can neither be
checked by any insulator nor retarded by
any obstruction.
"Sixth-Its energy is Interchangeable in
time; certainly for the past 1000 years;
presumably = indefinitely. Corollary:
hence, sixth (b), its activity is incessant, and
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