The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1870-08-16
rs TIRE WORLD ROUyDp


MI. John Hampden Tor "Parallax") has re-
Gently backed his opinion to the contrary by
q sum of five hundred pounds; and an inter-
estihg experiment has taken place. This
gentleman, in 1865, published a book to prove
that the earth is plane, without motion. and
unaccompanied by anything in the armament
analogous TO itself. The whole question
turns on the convexity of water, for if the
earth is globe, and twenty-five thousand
miles in circumference, the surface of all
standing water must have a certain degree of
convexity; every part must be an arc of
circle, rising at the rate of about eight inches
per mile; and in every succeeding mile, eight
inches multiplied by the square of the dis
tance. Mr.. Hsmpden says he tried the fol-
lowing experiment:--In the Old Bedford
Canal, Cambridgshire, boat and
Welney Bridge, and remain at
Welche's Dam, six miles distant. Mr.. Hamp-
den, with a telescope, placed himself in the
water as bather, with his eye not exceeding
eight inches above the surface. The flag
and the boat down to the waters edge were
clearly visible throughout the whole distance,
30 that he concluded if the surface of the
water had risen as above mentioned, he could
not have seen the boat at ALL We have neither
the space nor the inclination to follow Mr..
Hampden in the far-fetched theories con-
tanned in his volume. Suffice it to say that
this gentleman offered to stake five hundred
pounds on his theory; and Mr. A. r. Wallace
accepted the challenge, offering, in like
manner, to stake five hundred pounds upon
the ISSUE and agreeing to "prove the con-
vexity or curvature of the surface of canal
river, or lake." The spot chosen was that
portion of the Old Bedford Canal between
Old Bedford Bridge and Welney Bridge, a
distance of six miles in a straight line.
Tho avparin,apt anna off Moroh 1870.
and an obloDg signal, six feet by three, was
placed on Old Bedford Bridge, its centre
being thirteen feet four inches above the
water. At three miles distance along the
canal 1--WE quote from the report of Mr.. Car
penter, Mr.. Hampuen's referee), a staff was
erected, having red disc of wood one foot
in diameter affixed to it, the centre of which
was also thirteen feet four inches above the
water; and on Welney Bridge, three miles
farther, third signal was placed, reaching
the top of the bridge, thirteen feet four
inches likewise above the water. The obser-
vations were made by means of q large tele-
scope four-inch obiect-glass), and also by
means of q sixteen. inch Troughton level,
placed in the same position and height above
the water as the large achromatic. On the
centre signal staff there was red disc, which
was allowed to remain nine feet four inches
above the water, or four feet lower than the
other.
Now the result was, that in each of these
observations, one taken from Welney Bridge,
and the other from Old Bedford Bridge, with
the large achromatic telescope, the two discs
of the central staff appeared in each case
above the other bridge, showing that the
signal-staff in the centre was higher, and
thus proving the convexity of the water.
Similar results appeared with the telescope
of sixteen-inch Troughton level, placed in
fhac Tba IS
could not agree, and the editor of the Field
was called in as referee. He decided that
MIR. Wallace, by means of the experiment
agreed on, has proved to his satisfaction
the curvature to and fro" of the Bedford
Canal to the extent of five feet more or less.
He therefore paid Mr.. Wallace the one thou
sand pounds that had been lodged at Coutts
Bank
Mr.. Wallace, in letter to the Field april
2, 1870, commenting on Mr. Carpenters re-
marks in his report, says that that gentleman
objects to the value of the view in the large
telescope "because it showed but two points,
when a comparison had to be instituted be-
tween three;" but he omits to state that the
telescope itself was placed accurately at the
third point, just as was the spirit-level tele-
scope-to the view shown by which he makes
no objection. The views from both extrem-
ties of the six miles agreeing so closely, both
used; and that it may be depended upon to
show that the surface of water does really
sink below the true level line in a continually
increasing degree as the distance is greater:
but the proof of convexity in no way depends
on this accuracy, as it was shown still better
by the large telescope without spirit-level.
The curvature shown by the large telescope
is about five and a-half feet at the middle
signal, three miles distant; equal to eleven
Co. 1ot +I,a III, Il
the depression below the cross-hair or true
level line being, according to Mr.. Carpenter,
an equal amount, makes twenty-five feet in
all, leaving less than two feet for refraction
to bring it to the full theoretical amount
which is something less than twenty-four
feet. The three points deviated in a vertical
direction very nearly as much as is required
by the assumed dimensions of the
earth, so that We may conclude that the level
telescope line is tangent to a circle, approx
mately the circle of the earth. Mr.. Vernon
says, if the telescope in this experiment had
been laid exactly at right angles to plumb
line dropped from its centre, ii would have
been found that the surface of the water
three miles off was six feet, and at six miles
twenty four feet, lower than the water at the
spot where the observation was made.
Homer considered the world as fiat. Mr.
Gladstone, in his 'Studies of Homer and tn,
Homerlc Age, states that In Homers esti
nation the form of the world was not circu
lar, but oval, having shorter diameter from
east to west than from north to south Ii
the map he gives it is in the form of par
allelogram with rounded edges, like tn,
oblong shield then in use. The merit of tn
discovery of the spherical form of the eartl
is due to the Pythagoreans, who came to tn
conclusion from astronomical observations
but it is uncertain whether Pythagoras wa
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