1 gramme = 15·432 grains.
1 litre = 35¼ fluid ounces.
The plate of glass being thus carefully silvered is allowed to dry
thoroughly, and is finally varnished with a good thick varnish,
containing plenty of red lead, so that the back surface of the silver
mirror has a smooth and red appearance, while the varnish protects the
delicate film of metallic silver.
An ordinary photographic picture on glass is really represented by
precipitated metallic silver, but the metal in this case is in minute
particles, which do not shine or reflect light.
The silvered plate glass is now engraved in the following simple
manner. Being placed in a support or rack against the wall, and quite
upright, a chisel—or rather, a series of chisels—are drawn across the
surface in straight lines, and perpendicular, by the use of a large
=T=-square. Every time the chisel is drawn with pressure across the
varnished back of the glass a portion of the silver is removed, leaving
a straight line quite clear or transparent, and, in fact, laying bare
the surface of the plate glass.
The lines were ruled in three degrees of comparison: thick, thicker,
thickest; and considerable skill and experience—which no description
can teach—were required to get these correctly engraved.
[Illustration: A B C D, the Plate Glass; _e_ straight lines engraved on
silvered side and gradually increasing in thickness from _e_ to _f_.]
The engraved silver glass plate moved through a groove in the
woodwork at the top of the chamber, and was supported below on a
beautiful carriage, the wheels of which were covered with vulcanised
indiarubber rings, and moved on a tramway below the floor of the
room, perpendicularly. The glass could be made to slide at an angle
of forty-five degrees, and as it always made a rumbling noise while
moving, the music of the band concealed that defect. The ground plan of
the apartment is shown on the opposite page.
Some idea of the cost of making a full-sized apparatus, with hangings
and curtains and engraved glass, may be gathered from the fact that
the author’s outfit for Australia with a certain number of dresses
cost £327 12s. 1d. Whilst the author was travelling through Australia
Mr. James Walker, with his great inventive genius, made a further
improvement, by which the concealed figure at K was done away with,
and the whole apartment thrown open to the public gaze. This was done
to illustrate a clever sketch written by Mr. Burnand called “Curried
Prawns.”
[Illustration: Ground plan of chamber.
A A′A″A‴, floor of the apartment; B B, groove at an
angle of 45°, in which the glass moved; A″ to C
groove continued outside of the apartment used when
the glass was moved away; E F G H, short flight of
three or four steps, as the room must stand some
distance from the floor to allow of carriage moving
on tramway.
=N.B.=—The groove A to C was concealed from the
audience by handsome curtains, which were repeated
at the same angle on the other side, from M to D.
K.—Place where the objects to be reflected in the
looking-glass were placed, but quite concealed
from the audience with a door, closed when the
exhibition was going on.
]
[Illustration]
A C D E are the outside of the room, 12 feet square, engraved glass
running from H A to A D. The wing E G is placed square; this is an
immense advantage, as it renders unnecessary any counterpart at C N,
and as, of course, it cannot be seen, the light from the foot-lights on
E G is not seen by reflection at C N. When the wing E G was at the same
angle as H A, this was always a weak point in the illusion, as when the
glass crossed, the reflection of E G, unless very dimly illuminated,
always shewed. Now it does not matter when E G is placed as in drawing.
The frontage to the audience, instead of being from A F, is now
extended to E—_i.e._ 12 feet—consequently the return sides F E and C
B can be removed. This plan, of course, precludes the use of “trick”
chairs, baskets, &c. &c.; but it has a good many other advantages in
its favour, for with a “sociable” in the middle of the room made in
two exact halves, these halves trick or cover one another when the
glass is pushed across, and of course this movement is not seen by the
audience; then any person or persons can be made to appear gradually,
sitting or standing, at L or M, _right in the middle of the wide open
room_. Mr. Walker tried this effect at the Polytechnic Institution, and
it was capital—the ensemble is more imposing. This plan of shewing the
illusion is the plan for the stage, as the necessity for darkening the
stage in front is nearly wholly avoided. The back of the side-wing I
K can be painted black, so that its reflection shall not be seen. In
lieu of the gas-jets, as now arranged, there is a gas-lamp; this is
placed on a pedestal or small table. The shadow of the “sociable” to a
great extent covers or hides the path along which the glass travels.
Mr. Walker says: “I thought out this way for Mr. Irving’s necessities,
but I did not hear anything from him; and it has come in well for Mr.
Burnand’s sketch, which has been produced.” In this sketch, a gentleman
afflicted with dyspepsia through eating “curried prawns” (the name of
the piece), calling on some friends, where he has promised to help
them in some amateur theatricals, looks at the different costumes of
Mephistopheles, Faust and Marguerite, and throws them carelessly on
the seat at M, walks down the steps (which we shall double in width)
the glass now crosses, and, whilst in a fit of melancholy, he wonders
if Mephistopheles will appear. Sure enough, he does. Mephistopheles
then comes down in front, and with incantations makes, successively or
together; Faust and Marguerite appear; they then disappear in the same
manner.
The author’s friends and the public all know how steadily he has
opposed the so-called _Spiritual deceptions_, which generally are not a
half nor a quarter as clever as the tricks of a first-rate conjuror.
_Punch_ instructs us what to do at a Spiritual séance, which, if
done, would certainly astonish the person performing the part of the
materialised spirit. _Punch_ writes—“How to behave at a Spiritual
séance.—Always try to hit the happy Medium.”
The author thought the time had now arrived when a new generation who
knew not the ghost might be interested in its revival, and with that
idea the authorities at the present Polytechnic concurred, so that by
the time these pages are read it is hoped the ghost will be in full
career once more, and if the author only receives a tenth part of the
great patronage he received in 1863 he will be amply repaid for all his
exertions in reproducing the ghost illusion. And he desires thankfully
to acknowledge the very kind help he has received from Robert Mitchell,
Esq., the Secretary and Manager of the numerous classes and useful
lectures now so well conducted at Mr. Quintin Hogg’s Polytechnic.
* * * * *
The author hopes to show “something new” at the Polytechnic; and a
lady in miniature, as it were from Liliput, dances on a silver waiter
held out by the author; and the great man Napoleon I., for whom, like
Alexander the Great, the world was too small, stands in the palm of the
hand of the author.
If “duffers,” &c., did not exist, the illusion would be explained to
the public; but ten years need not elapse before they know all.