s strong evidence of considerable
efficiency in the instruments, and of careful attention on the part of
the observer, that Lussac was able to record the temporary inversion
of the law of change of temperature above-mentioned. Had he possessed
modern instrumental equipment he would have brought down a yet more
remarkable account of the upper regions which he visited, and learned
that the variations of heat and cold were considerably more striking
than he supposed.

With a specially devised instrument used with special precautions, the
writer, as will be shown hereafter, has been able to prove that the
temperature of the air, as traversed in the wayward course of a balloon,
is probably far more variable and complex than has been recorded by most
observers.

The exceptional height claimed to have been reached by Gay Lassac need
not for a moment be questioned, and the fact that he did not experience
the same personal inconvenience as has been complained of by mountain
climbers at far less altitudes admits of ready explanation. The physical
exertion demanded of the mountaineer is entirely absent in the case of
an aeronaut who is sailing at perfect ease in a free balloon. Moreover,
it must be remembered that--a most important consideration--the aerial
voyager, necessarily travelling with the wind, is unconscious, save
at exceptional moments, of any breeze whatever, and it is a
well-established fact that a degree of cold which might be insupportable
when a breeze is stirring may be but little felt in dead calm. It should
also be remembered, in duly regarding Gay Lussac's remarkable record,
that this was not his first experience of high altitudes, and it is an
acknowledged truth that an aeronaut, especially if he be an enthusiast,
quickly becomes acclimatised to his new element, and sufficiently inured
to its occasional rigours.

CHAPTER V. SOME FAMOUS EARLY VOYAGERS.

During certain years which now follow it will possibly be thought that
our history, so far as incidents of special interest are concerned,
somewhat languishes. Yet it may be wrong to regard this period as one of
stagnation or retrogression.

Before passing on to later annals, however, we must duly chronicle
certain exceptional achievements and endeavours as yet unmentioned,
which stand out prominently in the period we have been regarding as also
in the advancing years of the new century Among these must in justice
be included those which come into th