ange in the colours produced by the prism? What would be the
constitution of the higher and more attenuated air? What physical effect
would it have on human and bird life?

The ascent was made at 7.15 on a summer evening by M. Robertson and
the Academician, M. Sacharof, to whom we are indebted for the following
resume of notes, which have a special value as being the first of their
class. Rising slowly, a difference of atmosphere over the Neva gave the
balloon a downward motion, necessitating the discharge of ballast. As
late as 8.45 p.m. a fine view was obtained of the Newski Islands, and
the whole course of the neighbouring river. At 9.20 p.m., when the
barometer had fallen from 30 inches to 23 inches, a canary and a dove
were dismissed, the former falling precipitately, while the latter
sailed down to a village below. All available ballast was now thrown
out, including a spare great coat and the remains of supper, with the
result that at 9.30 the barometer had fallen to 22 inches, and at this
height they caught sight of the upper rim of the sun. The action of
heart and lungs remained normal. No stars were seen, though the sky was
mainly clear, such clouds as were visible appearing white and at a great
height. The echo of a speaking trumpet was heard after an interval of
ten seconds. This was substantially the outcome of the experiments. The
practical difficulties of carrying out prearranged observations amid the
inconvenience of balloon travel were much felt. Their instruments were
seriously damaged, and their results, despite most painstaking and
praiseworthy efforts, must be regarded as somewhat disappointing.

But ere the autumn of the same year two other scientific ascents,
admirably schemed and financed at the public expense, had been
successfully carried out at Paris in a war balloon which, as will be
told, had at this time been returned from military operations in Egypt.
In the first of these, Gay Lussac ascended in company with M. Biot, with
very complete equipment. Choosing ten o'clock in the morning for their
hour of departure, they quickly entered a region of thin, but wet
fog, after which they shot up into denser cloud, which they completely
surmounted at a height of 6,500 feet, when they described the upper
surface as bearing the resemblance, familiar enough to aeronauts and
mountaineers, as of a white sea broken up into gently swelling billows,
or of an extended plain covered with snow.

A series of s