The Bloomfield times. [volume] (New Bloomfield, Pa.) 1867-187?, 1872-04-02
SCIENTIFIC READING.
AIR AND w ATE r.
How a Discovery was Made.

HNHE air pump, rude, it is true, in its
Il construction, had long been known,
and the common pump for raising water
from wells had been in use for centuries.
In the latter drawing the piston up, it was
known, would cause tho water to follow;
and when the philosophers were asked to
explain the reason, in their wisdom, they
said, at is because nature abhors vacu-
um." And this answer had satisfied even
the wisest men in the world for two thous
and years; nor can we tell how much longer
it would have sufficed, had not the facts
which it seemed to explain, at last over
turned it. 1t was near the middle of the
seventeenth century that the Duke of Tus-
cany had caused we'll to be dug near Flor
ence; it was sunk to an unusual depth for
those days, for this was long before car
tesians" were thought of. Not suspecting
any change, from the usual programme, the
engineers fitted their pump, when, TO- it
would not serve it's purpose. The water
would rise little over thirty feet from the
bottom, and there stop. Repairs were
made; then all the changes which their
ingenuity could devise, but nothing could
coax the water above the point at which it
so obstinately stood. At last in their des-
pair, they applied to the wisest philosopher
of the day. to see if he could solve the mys-
terry. This was Galileo, then, in his old
age, living in retirement, not far from Flor
ence. When the story had been recounted
to him, he is said to have replied, half in
jest, half in earnest, that "nature did not
abhor vacuum above ten meters ~ At an
earlier age he might have been more sue
cessful in solving the riddle; but then, this
was the best answer he could give. The
question was submitted to his pupil, Tori
celli, who very sooh saw that some mechdn-
zeal force, not ficticious sentiment must
raise the water to just the hight and hold
it there. Suspecting the true cause, the
pressure of the atmosphere, he reasoned
that, if it were truly this, it would raise
heavier liquid, only to proportionately
less hight and, since mercury was thirteen
and half times heavier than water, a
simple calculation told him that this should
rise only from twenty eight to thirty
inches, instead of thirty or thrty-three
feet. Taking therefore glass tube closed
at one end, and vessel of mercury, he ex-
hausted the air from the tube, applied his
fingers so as to close the other end, while
he just dipped it beneath the surface of his
mercury. Upon removing his finger he
was delighted to see the mercury rise to
after vibrating moment about it, settle
there. To his own mind the question was
| solved; and not only this, but he had here
the means of weighing the whole atmos-
phere, for a column of this of equal base
with the bottom of the tube must weigh
just the same as mercury which it balanced.
With this as data it was an easy step to
compute the weight of the whole atmos-
phere which surrounds the earth. He an
swered the engineers question and began
to publish his discovery to the world. But,
as might have been expected, very few be-
lieved his theory, the great majority pre-
ferring to stick to the old philosophy of
their fathers, that "nature abhored q
vacuum" ten metres if no more.
Torricelli did not live to see his views be-
come the prevailing opinion, but they began
gradually to make their way, and after his
death philosopher as keen as himself
took them up and succeeded in convincing
the world Of their truth. The philosopher
was Pascal, who began to say that If it was
really the atmosphere which sustained the
mercury, the higher he should ascend from
the earth, the less being the weight of the
air above, the less consequently would be
the hight Of the column Of mercury which
it would balance. Living in Paris, he took
his tube to the top of the highest steeple to
to which he could gain access in the city,
and was delighted to find that the mercury
fell, though slightly. Not satisfied with
this, he wrote to his brother-in-law, living
near high mountain in the province of
Auvergne, TO try it there. This he did,
and found difference Of about three inches
in the measure Of his mercury between the
bottom and the top Of the mointain, while
at the various points in the ascent the ele-
walton was accurately marked by the diff
ference in the elevation Of his sensitive in
strument; (which" he writes to Pascal,
"ravished us with admiration and aston
ishment." And so the theory Of the pres
sure Of the atmosphere was proved beyond
a doubt to all but the most obstinate, and
not only so, but the most convenient, as
well as an accurate wav of tneasurir,o ele