much more striking effects. It is a much larger instrument than the
other, and when it is exhibited a screen is placed between it and the
spectators, so that they do not see how the pictures are produced. It
is mounted on castors, so that at times it can be brought nearer and
nearer to the screen, until the picture seems to enlarge and grow in a
wonderful manner. Then, when it is drawn back, the image diminishes
and recedes far into the distance. The lenses and other mechanism of
the phantasmagoria can also be moved in various directions, making the
action of the pictures still more wonderful. Sometimes, when the
instrument is exhibited in public, the screen is not used, but the
pictures are thrown upon a cloud of smoke, which is itself almost
invisible in the dim light of the room. In such a case the figures
seem as if they were floating in the air.

A man, named Robertson, once gave exhibitions in Paris, in an old
chapel, and at the close of his performances he generally caused a
great skeleton figure of Death to appear among the pillars and arches.
Many of the audience were often nearly scared to death by this
apparition. The more ignorant people of Paris who attended these
exhibitions, could not be persuaded, when they saw men, women, and
animals walking about in the air between the arches of the chapel,
that Robertson was not a magician, although he explained to them that
the images were nothing but the effect of a lantern and some glass
lenses. When these people could see that the figures were produced on
a volume of smoke, they were still more astonished and awed, for they
thought that the spirits arose from the fire which caused the smoke.

But Robertson had still other means of exhibiting the tricks of light.
Opposite is a picture of the "Dance of Demons."