becomes under ordinary circumstances unavoidable. Hence it is not only
an amusing but an useful occupation to acquire a knowledge of those
causes which are capable of producing so strange a belief, whether it
arises from the delusions which the mind practises upon itself, or from
the dexterity and science of others.

(The Optical phenomena, as might be expected, are most abundant, as they
include the subject of spectral illusions and apparitions, and natural
phenomena marked with the marvellous. The properties of Sound are next
in interest; among them we find explained the wonder of singers breaking
glasses with their great power of voice; the automaton flute-player,
talking engines, echoes, &c. The Mechanical causes are less numerous:
among them we are glad to see _noticed_ the feat of lifting heavy
persons, which we ourselves have often seen accomplished; but Sir David
Brewster does not supply the cause. As the matter may be new to many
readers, we quote the two relating pages.)

One of the most remarkable and inexplicable experiments relative to the
strength of the human frame, which you have yourself seen and admired,
is that in which a heavy man is raised with the greatest facility, when
he is lifted up the instant that his own lungs and those of the persons
who raise him are inflated with air. This experiment was, I believe,
first shown in England a few years ago by Major H., who saw it performed
in a large party at Venice under the direction of an officer of the
American Navy. As Major H. performed it more than once in my presence, I
shall describe as nearly as possible the method which he prescribed. The
heaviest person in the party lies down upon two chairs, his legs being
supported by the one and his back by the other. Four persons, one at
each leg, and one at each shoulder, then try to raise him, and they find
his dead weight to be very great, from the difficulty they experience in