were elaborated at this period; but
one that was designed in America by Mr. Henson, and with which it was
seriously contemplated to attempt to cross the Atlantic, may be briefly
described. In theory it was supposed to be capable of being sustained in
the air by virtue of the speed mechanically imparted to it, and of
the angle at which its advancing under surface would meet the air. The
inventor claimed to have produced a steam engine of extreme lightness
as well as efficiency, and for the rest his machine consisted of a huge
aero-plane propelled by fans with oblique vanes, while a tail somewhat
resembling that of a bird was added, as also a rudder, the functions of
which were to direct the craft vertically and horizontally respectively.
Be it here recorded that the machine did not cross the Atlantic.

One word as to the instruments used up to this time for determining
altitudes. These were, in general, ordinary mercurial barometers,
protected in various ways. Green encased his instrument in a simple
metal tube, which admitted of the column of mercury being easily read.
This instrument, which is generally to be seen held in his hand in
Green's old portraits, might be mistaken for a mariner's telescope. It
is now in the possession of the family of Spencers, the grandchildren
of his old aeronautical friend and colleague, and it is stated that with
all his care the glass was not infrequently broken in a descent.

Wise, with characteristic ingenuity, devised a rough-and-ready height
instrument, which he claims to have answered well. It consisted simply
of a common porter bottle, to the neck of which was joined a bladder of
the same capacity. The bottle being filled with air of the density of
that on the ground, and the bladder tied on in a collapsed state, the
expansion of the air in the bottle would gradually fill the bladder as
it rose into the rarer regions of the atmosphere. Experience would then
be trusted to enable the aeronaut to judge his height from the amount of
inflation noticeable in the bladder.

CHAPTER XII. HENRY COXWELL AND HIS CONTEMPORARIES.

Mention should be made in these pages of a night sail of a hundred
miles, boldly carried out in 1849 by M. Arban, which took the voyager
from Marseilles to Turin fairly over the Alps. The main summit was
reached at 11 p.m., when the "snow, cascades, and rivers were all
sparkling under the moon, and the ravines and rocks produced masses of
darkness which serve