236 
POPULAK SCIENCE REVIEW. 
which the paint has adhered are scratched off with a sharp-pointed instru- 
ment, so as to expose the metal beneath those parts. The plate is next 
plunged into a bath containing nitric acid, or aquafortis ; the acid enters 
all the parts from which the wax has been removed and bites through 
them. All the pores and veins of. the wood are thus reproduced by the 
spaces bitten out of the metallic plate. The plate is washed with water 
to cleanse it, and the wax is removed by a bath of essence of turpentine 
or other spirit. The metal plate thus prepared serves for the reproduction 
of the veins, pores, knots, and figures of wood upon any surface, whether 
previously prepared by oil, paint, or otherwise. For instance, the plate 
is applied upon a surface painted with a ground colour, and a brush 
charged with paint of the colour of natural veins and knots is passed over 
the plate ; the paint passes through the spaces or openings in the plate, 
and adheres to the surface beneath such spaces or openings only ; and thus 
an exact copy of the veins, pores, knots, and figures of the Avood is 
obtained. 
Apparatus to be used in Dramatic and Similar Performances. — 
Messrs. DircJcs and Pepper, 'patentees. — (Plate X.) — The object of this inven- 
tion is, by a peculiar arrangement of apparatus, to associate on the same stage 
a phantom or phantoms with a living actor or actors, so that the two may 
act in concert ; but which is only an optical illusion as respects the one or 
more phantoms so introduced. The arrangement of the theatre requires, 
in addition to the ordinary stage, a , a second stage at a lower level than the 
ordinary one, hidden from the audience as far as direct vision is concerned ; 
this hidden stage is to be strongly illuminated by artificial light, b , c, and 
capable of being rendered dark instantaneously, while the ordinary stage 
and the theatre remains illuminated by ordinary lighting. A large glass 
screen, f, is placed on the ordinary stage and in front of the hidden one. 
The spectators will not observe the glass screen ; but will see the actors 
on the ordinary stage through it, as if it were not there ; nevertheless, the 
glass will serve to reflect to them an image of the actors on the hidden 
stage when these are illuminated ; but this image will be made imme- 
diately to disappear by darkening the hidden stage. The glass screen is 
set in a frame so that it can readily be moved to the place required, and it 
is to be set at an inclination, to enable the spectators, whether in the pit, 
boxes, or gallery, to see the reflected image. The glass is adjustable, and 
it is readily adjusted to the proper inclination by having a person in the 
pit and another in the gallery to inform the party who is adjusting the 
glass when they see the image correctly. The right hand portion of the 
Plate (Plate X.) represents the stage arrangements. The left is an ideal 
section of the pit, boxes, and gallery of a theatre. 
Brewing. — Mr. J. Maxfield , patentee. — It is desirable that the 
yeast arising from malt liquors should be kept separate from the 
liquor as it rises during the process of fermentation ; and that the 
carbonic acid gas should be retained in the malt liquor, and the 
too free entrance of air be prevented. These improvements consist in 
the use of a cover floating upon the surface of the malt liquor, and 
furnished at the edges with india-rubber, to form an air and water tight 
joint between the edge of the cover and the inside of the vat. This floating 
