of steering balloons being obtained. It even appeared to me that
the balloon itself, admirable for vertical ascents, was not necessarily
a first step in aerial navigation, and might possibly have no share
in the solution of the problem. It was this conviction that led to
the formation of the Aeronautical Society a few years since under the
presidency of the Duke of Argyll. In the number of communications made
to this society it is evident that many minds are taxing their ingenuity
to discover a mode of navigating the air; all kinds of imaginary
projects have been suggested, some showing great mechanical ingenuity,
but all indicating the want of more knowledge of the atmosphere itself.
The first great aim of this society is the connecting the velocity of
the air with its pressure on plane surfaces at various inclinations.

"There seems no prospect of obtaining this relation otherwise than by a
careful series of experiments."

CHAPTER XIV. THE HIGHEST ASCENT ON RECORD.

Mr. Glaisher's instrumental outfit was on an elaborate and costly scale,
and the programme of experimental work drawn up for him by the Committee
of the British Association did not err on the side of too much modesty.
In the first place the temperature and moisture of the atmosphere were
to be examined. Observations on mountain sides had determined that
thermometers showed a decrease of 1 degree F. for every 300 feet,
and the accuracy of this law was particularly to be tested. Also,
investigations were to be made as to the distribution of vapour
below the clouds, in them, and above them. Then careful observations
respecting the dew point were to be undertaken at all accessible
heights, and, more particularly, up to those heights where man may be
resident or troops may be located. The comparatively new instrument, the
aneroid barometer, extremely valuable, if only trustworthy, by reason of
its sensibility, portability and safety, was to be tested and compared
with the behaviour of a reliable mercurial barometer. Electrical
conditions were to be examined; the presence of ozone tested; the
vibration of a magnet was again to be resorted to to determine how
far the magnetism of the earth might be affected by height. The solar
spectrum was to be observed; air was to be collected at different
heights for analysis; clouds, also upper currents, were to be reported
on. Further observations were to be made on sound, on solar radiation,
on the actinic action o