read
minus 12 degrees, and that reading would indicate an elevation exceeding
36,000 feet. There cannot be any doubt that the balloon attained the
great height of seven miles--the greatest ever reached. In this ascent
six pigeons were taken up. One was thrown out at three miles. It
extended its wings, and dropped like a piece of paper. A second at four
miles, and it flew with vigour. A third between four and five miles, and
it fell downwards. A fourth was thrown out at four miles in descending,
and it alighted on the top of the balloon. Two were brought to the
ground. One was dead, and the other was ill, but recovered so as to fly
away in a quarter of an hour."
The results gathered by Mr. Glaisher from his numerous ascents are very
interesting. He found that in no instance did the temperature of the air
decrease uniformly with the increase of height. In fact, the decrease
in the first mile is double that in the second, and nearly four times as
great as the change of temperature in the fifth mile. The distribution
of aqueous vapour in the air is no less remarkable. The temperature
of the dew-point on leaving the earth decreases less rapidly than
the temperature of the air; so that the difference between the two
temperatures becomes less and less, till the vapour or cloud plane is
reached, when they are usually together, and always most nearly approach
each other, and that point is usually at about the height of one mile.
On leaving the upper surface of cloud, the dew point decreases more
rapidly than the air, and at extremely high situations the difference
between the two temperatures is wonderfully great, indicating an
extraordinary degree of dryness, and an almost entire absence of water.
Under these circumstances, the presence of cirrus clouds far above this
dry region, apparently as much above as when viewed from the earth, is
very remarkable, and leads to the conclusion that they are not composed
of water.
In the propagation of sound, M. Glaisher made many curious experiments.
In one ascent (July 17th) he found, when at a distance of 11,800 feet
above the earth, that a band was heard; at a height of 22,000 feet, a
clap of thunder was heard; and at a height of 10,070 feet, the report of
a gun was heard. On one occasion, he heard the dull hum of London at
a height of 9,000 feet above the city, and on another occasion, the
shouting of many thousands of persons could not be heard at the height
of 4,000 feet.
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