feathers. As there are octapoda which swim
by means of membranes instead of fins, there
are mammals which fly by means of membranes
instead of wings. Bats, called by the Savans,
hand-wings (Cheiroptera), hand-rats (Cheiromus),
and cat-monkeys (Galespithecus), can fly
by means of membranes. The bat flies best.
But the flight of the bat, compared with the
flight of the swallow, pigeon, or pelican, is a
poor performance. When a boy I have knocked
down many a bat with my Highland bonnet
on the roads of Aberdeenshire. No boy ever
thought of trying this game on with a swallow
or a sparrow. The bat spends most of his time
hanging to some projection in a hole, and flies
only for a few hours in the evenings of a few
weeks in the year. The aye-aye, or rat-monkey
of Madagascar, has a flat tail like a squirrel, and
derives its name from the exclamation of
astonishment which it excites when seen leaping,
bounding, or almost flying from tree to tree in
the dusk of the evening. The cat-monkeys have
been mistaken for bats. The fingers of the bat
are long, thin, light, cylindrical, and hollow;
and the bat flies by using the fine membrane
between them as a wing. The membrane of
the cat-monkey, on the contrary, is not a wing,
or aerial oar, but is a sort of parachute spreading
over the back, and expanded and regulated
by the four arms and hands. The parachute
spreads over the whole back of the body from
the lips to the fingers, and covers the tail.
Some of these cat-monkeys can fly a hundred
yards or more in an oblique and inclined line.
The female flies with her little one at her breast.
Now, not merely is the humerus of all these
animals with membranes on their hands and
backs, long, slim, and hollow; there are
connected with it one or two holes, and one of
these holes communicates with the instruments
of smell. Certain bats have also a curious
"rotule brachiale," as the French call it, or
arm-wheel (Patella brachialis), which was
discovered by Mechlin in the extensor muscle of
the fore arm of the vampire bat. The swimming
lizards have also this bone, which, therefore, is
probably useful for floating in water and air.
The kalong, or fox-bat, is said to take long,
straight, slow flights from forest to forest, and
from plantation to plantation, in search of fruit.

The differences between bats and birds, viewed
as flying machines, are mere differences of form.
The birds owe their buoyancy to gaseous structure,
and their waftage to their feathered wings;
and the bats owe their buoyancy to gaseous
structure, and their waftage to membraneous
wings. The flying-fish have pectoral fins, so
long and wide that they serve as wings for a
time. The skin of the flanks of the flying
squirrels, extending from their fore to their
hind legs and feet, forms a parachute under
them, as the skin of the cat-monkeys forms a
parachute over them. On the whole, then, I
submit that buoyancy is proportional to gaseous,
and waftage to wing structure; and when both
are most perfect, the flying is most perfect.

A strong confirmation of these views is
obtained from an examination of the floating
machines which ingenious men have successfully
built, and from the attempts which they have
unsuccessfully made to build flying machines
adapted for the air. Mechanical invention can
produce ships which float in the air, but it
cannot guide them there. Balloons are ships
at the mercy of the winds and tides, without
sails and rudders. By throwing out ballast
they can be sent up, and by letting off gas
they can be let down; but they cannot be
steered to any given spot. Any master mariner
can say, "Hoist a flag on any spot you like of
the ocean, which covers three-fourths of the
globe, and I will take my ship to it;" but the
sailors in the air can go up and be swept about,
and they can come down, and this is all they
can do. When shall they be able to say,
"Hoist a flag on any peak you like of the
Andes, or the Himalayas, and I will anchor my
air-ship there?"

The best models for air-ships or boats were
probably the wing-fingers or pterodactyles, now
only found as fossils. These bats had aerial
oars of membraneous structure, measuring some
thirty or forty feet from tip to tip.

The imitation of wings seems to have been
the first notion of the air sailors:

Then with expanded wings he steers his flight,
Aloft incumbent on the dusky air,
That felt unusual weight,

says Milton, describing Satan; and the makers
of flying-machines, from the earliest of them on
record down to the members of the British and
French Aeronautical Societies of the present
day, have always persisted in the error of
attaching undue importance to wings, and
insufficient importance to gas tubes, bags, and
cells. The young monk of Malmsbury, who, it
is said, flew from the steeple and broke his
bones, boasted that he would have succeeded
quite if he had only had a broad tail of feathers.
The Marquis de Bacqueville, who started to fly
across the Seine, from the roof of his house, to
the Garden of the Tuileries, about a hundred
and thirty years ago, found the working of his
wings beyond his strength, and fell down, and
broke his leg against a floating wash-house in
the Seine. Five or six hundred years ago a
man, who is said to have flown from a hill at
Bologna into the river Reno, was neither killed
nor drowned. Proving clearly, to the satisfaction
of the Holy Inquisition, that he was in
league with Satan, he was burnt.

Some success was obtained several centuries
ago in the construction and use of aërial
velocipedes. Friar Bacon, Bishop Wilkens, and
the Marquis of Worcester, all mention these
inventions. The editor of the pamphlet on
Aërial Locomotion, from the Transactions of
the Aeronautical Society of Great Britain,
quotes the following passage from "Astra
Castra," by Hutton Turner: "Soon after
Bacon's time, projects were instituted to train
up children from their infancy in the exercise of
flying with artificial wings; which seemed to