d of its circumference;
after which it descends on the inside and terminates at the
bottom. The tinfoil on the outside of the glass is divided by
cutting with a knife every 1/8 in., the parts inside and beneath
the glass being left undivided. Current is then led from a static
machine to two terminals, one terminal being connected to one end
of the tinfoil strip, and similarly the second terminal makes
contact with the other end. As soon as the current is led into the
apparatus, a spark is seen at each place where the knife has cut
through the tinfoil. If the tumbler is rotated, the effect will be
as shown in the illustration. A variety of small and peculiar
effects can be obtained by making some of the gaps in the tinfoil
larger than others, in which case larger sparks would be produced
at these points. The experiment should be carried out in a
darkened room, and under these circumstances when nothing is
visible, not even the tumbler, the effect is very striking.

** Balloon Ascension Illusion [300]
By C. W. Nieman

In these days of startling revelations in air-craft flight we are
prepared to see any day some marvelous machine driven bird cutting
figure-eights all over the sky above our heads. One boy recently
took advantage of this state of expectancy to have an evening's
harmless amusement, through an illusion which deceived even the
most incredulous. He caused a whole hotel-full of people to gaze
open mouthed at a sort of "Zeppelin XXIII," which skimmed along
the distant horizon, just visible against the dark evening sky,
disappearing only to reappear again, and working the whole crowd
up to a frenzy of excitement. And all he used was a black thread,
a big piece of cardboard and a pair of field glasses.

He stretched the thread between two buildings, about 100 ft.
apart, in an endless belt, passing through a screweye at either
end. On this thread he fastened a cardboard "cut-out" of a
dirigible, not much to look at in daytime, but most deceptive at
dusk. By pulling one or the other string he moved the "airship" in
either direction. He took the precaution of stretching his thread
just beyond a blackberry hedge and thus kept over-inquisitive
persons at a safe distance. He also saw to it that there was a
black background at either end so that the reversing of the
direction of the craft would not be noticed.

In attracting the crowd he had a confederate stand looking at the
moving ship through a field glass, w