others. This type is very stable and very fairly efficient.

General Remarks.--Always pick up a glider by the keel or middle, not by
one of the wings, as a very little distortion will give trouble.

The merits of a glider depend on length, and on straightness of flight; so
in competition the launching height should be limited by a string stretched
across the room, say 6 feet above the floor. If the room be too short for a
glider to finish its flight, the elevation at which it strikes the wall is
the measure of its efficiency.

Out-of-door flights are impracticable with these very frail models when
there is the slightest breeze blowing. On a perfectly calm day, however,
much better fun can be got out of doors than in, owing to the greater space
available. A good glider launched from a second-floor window facing a
large lawn should travel many yards before coming to grass.

Large gliders of the types detailed above can be made of very stout paper
stiffened with slips of cane or bamboo; but the time they demand in
construction might perhaps be more profitably spent on a power-driven
aeroplane such as forms the subject of the next chapter.

XXV. A SELF-LAUNCHING MODEL AEROPLANE.
By V. E. Johnson, M.A.

This article deals not with a scale model--a small copy of some
full-sized machine--but with one designed for actual flight; with one not
specially intended to create records either of length or duration, but
which, although small details must perforce be omitted, does along its main
lines approximate to the "real thing."

Partly for this reason, and partly because it proves a far more interesting
machine, we choose a model able to rise from the ground under its own power
and make a good flight after rising, assuming the instructions which we
give to have been carefully carried out. It is perhaps hardly necessary to
add that such a machine can always be launched by hand when desired.

Before entering into special details we may note some broad principles
which must be taken into account if success is to attend our efforts.

Important Points.--It is absolutely essential that the weight be kept
down as much as possible. It is quite a mistake to suppose that weight
necessarily means strength. On the contrary, it may actually be a cause of
weakness if employed in the wrong place and in the wrong way. The heavier
the machine, the more serious the damage done in the event of a bad
landing. One of the best and easiest