is, was engaged in building a navigable balloon, which, owing to the
unsettled state of affairs in France, did not receive its trial till two
years later. This balloon, which was inflated with pure hydrogen, was
of greater capacity than that of M. Giffard, being cigar shaped and
measuring 118 feet by 48 feet. It was also provided with an ingenious
arrangement consisting of an internal air bag, capable of being either
inflated or discharged, for the purpose of keeping the principal
envelope always distended, and thus offering the least possible
resistance to the wind. The propelling power was the manual labour of
eight men working the screw, and the steerage was provided for by a
triangular rudder. The trial, which was carried out without mishap, took
place in February, 1872, in the Fort of Vincennes, under the personal
direction of the inventor, when it was found that the vessel readily
obeyed the helm, and was capable of a speed exceeding six miles an hour.

It was not till nine years after this that the next important trial with
air ships was made. The brothers Tissandier will then be found taking
the lead, and an appalling incident in the aeronautical career of one of
these has now to be recorded.

In the spring of 1875, and with the co-operation of French scientific
societies, it was determined to make two experimental voyages in a
balloon called the "Zenith," one of these to be of long duration,
the other of great height. The first of these had been successfully
accomplished in a flight of twenty-four hours' duration from Paris to
Bordeaux. It was now April the 15th, and the lofty flight was embarked
upon by M. Gaston Tissandier, accompanied by MM. Croce-Spinelli and
Sivel. Under competent advice, provision for respiration on emergency
was provided in three small balloons, filled with a mixture of air and
oxygen, and fitted with indiarubber hose pipes, which would allow the
mixture, when inhaled, to pass first through a wash bottle containing
aromatic fluid. The experiments determined on included an analysis of
the proportion of carbonic acid gas at different heights by means
of special apparatus; spectroscopic observations, and the readings
registered by certain barometers and thermometers. A novel and valuable
experiment, also arranged, was that of testing the internal temperature
of the balloon as compared with that of the external air.

Ascending at 11.30 a.m. under a warm sun, the balloon had by 1 p.m.
reach