The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-07-25

tainty in such a calculation (Which con-
sumed three years., but the result, com
! pared with the density of a cubic foot OF
| water, appeared to be All. A subsequent
] similar experiment elsewhere resulted in
! the value of 5.32.
( The dmunition Of gravity in descending
| into a deep mine was also made use of as
/ a means of ascertaining the density of the
! earth. The result in this case was $50
/ subject also much uncertainty. The COM
| parision OF pendulum experiments at the
/ top and bottom of a mountain indicated in
| an aprpeciably less amount But a meth
/ cd which was first employed in 1898 Is re-
| garded as superior to all others.
| Although the principle was conceived by
the Rev. Mr.. Michel, the experiment" is
] named after Henry Cavendish, the distin-
| guished and wealthy physicist who actu-
| ally brought il into use. 1t embraces a
| DAINTY torsion balance" consisting of a
| very light rod, withsa small weight at each
| end, Suspended horizontally by long. fine
! silver wire and carefully enclosed in case
/ TO protect it from air CURRENTS. Two very
| neaVy balls on turn table are brought
close to the little weights. with the result
| that their attraction turns the rod in their
| direction. Afterward their position is re-
Versed, whereupon the rod turns the other
| way.
In one experiment in this realm of infn-
Intestinal attraction the leaden weights at
! tached to the rod being two inches in diam
! eter and the large leaden spheres weigh
ing 94S pounds-their centers being separ-
ated $50 inches-the point attraction
amounted to 1-4300 zone forty-three hun
| dredth of a grain!
| The greatest pains are necessary to pre-
vent the interference of heat from the OBJ
servers body and other disturbances, the
vibrations and reflections being viewed
| from a distance through a telescope. The
torsion' or twist of the wire is, of course
an important factor of the experiment as
| well as the resulting arc Of detection upon
the part of the rod.
II is a high tribute to the efficiency of
thls most delicate method, and also to
| the patient and painstaking physicists.
VINO have employed it with various modi-
| Hcatlons, that the results have been close
| ~ accordant; the mean being about
| 5.6O-i. e., the earth Is more than So times
as heavy as if it were composed of water.
and Is probably as dense at the center as
| the heavy metals
| Assuming that this figure is trustworthy.
| our task is now easy. By simple mensura-
| ton we find the number of cubic feet in
the terrestrial spherod and multiply it
| by SO times the weight of a cubic foot
| OF water (56 times 6212 pounds. Perhaps
we will be startled at the result, for, ex-
| pressing ii in tons we have, approximate
! ly: 100000, 600, 100000 10000.
How viii this help US to weigh the sun?
| Because our modern Archimeds has
found fulerum for his lever-we have
| something to WeghW it'll We must now
| determine how much the earth falls"
| to the sun in its orbltal movement. /. e.
| how much 1t deviates from straight line
| as the result of gravitation. The amount
is but little more ttan one-ninth of an
inch per second during a movement of 1872
| miles.
| int DIa ~.
| lestial mysteries presented to us by the
| genius of Newton, and remembering that
attraction varies inVersely as the square
| of the distance, we work backward over
the nearly 93,00O,0O0 miles of the SUMS dis
| lance to find that his attractive power or
mass" is about 331 600 times that of the
| earth. Multiply the weight of the earth
given above by this factor and we find the
weight" of the sun in tons to be 100000
| 900, 900, 000, 000, 900, 000, 600!
Since its volume, however, is really
| 100000 times greater than that of the
earth, its density can only be one-fourth
that of our planet
| All of the planets which have satellites
are in consequence provided with compar.
| atively simple self-weighing apparatus,
| but the determination of the masses of
| Mercury and Venus is a very different
matter, depending as il does upon the
| 'perturbations' they create, the derange-
| meHlS Oh edcn OtnerS orDltal mechanism
as we'll as that of the earth.
1t must be observed that astronomical
| science does not usually concern itself
with the sort of expressions we have been
| using, but rather employs terms of the
| earth's or the SUMS mass. Taking the
| earth's mass as standard, we have seen
| that while the sun is 100000 times
larger, its mass Is only 3S1, 900 times as
great. The volume of Mercury is about
one-eighteenth and its mass perhaps one
| seventeenth that of the earth. Venus
but slightly smaller than the earth, has
a mass of about 70 per cent. of that of her
| twin sister"
The mass of Mars is about one-ninth
and its volume one-seventh that of the
earth. As TO the asteroids, lie Verrier
showed that, combined, their mass would
not be greater than one-fourth that of the
| earth.
The huge Jupiter is 1909 times as large
as the earth, but his mass is only 316
times greater which exhibits the remark
| able feature that his density is almost
| exactly the same as that of the sun. Al
| though Saturn is 760 times larger than the
| earth, its mass is only ninety-ive times
| that of our planet. This beautiful ringed
| globe easily bears the palm as the light
est of the suns retinue. Uranus exceeds
US in volume slxty-six times, but only
| possesses a fourteen-fold mass. And the
| dim Neptune, not at all too distant to
| weigh, has a mass only seventeen times
that OF the earth, although eighty-five
times larger.