SCIENTIFIC SUMMARY. 
479 
A Pocket Microscope of a very cheap description has been constructed by 
Messrs. Frith. It is intended to be used by amateurs in the examination of 
mites and “ wheel insects.” It is simply an extremely small lens, whose cor- 
rections are imperfect. This is approximated by a screw to a glass disc 
on which the object is placed. The makers’ description will interest 
readers who are versed in microscopical terminology. It states that the 
instrument is divided into four parts, viz., “the Eye-piece, composed of two 
screws in the centre, between which is placed the lens, or magnifying glass ; 
2nd — the Object-glass, on the centre of which the objects are placed, and 
which is fixed to No. 3, or the body or tube ; 4th — the Condenser of 
natural light, at the extreme end, which must be used only by daylight and 
taken off by gaslight, when the observer must point the open end of the 
tube towards the gas or candlelight, to receive the rays direct.” We may 
state that the condenser is simply a diaphragm, with an aperture of £ inch 
diameter. 
PHOTOGRAPHY. 
Improved Process for making Photographic Transfers. — Amongst recent 
patents connected with photography is one taken out by Mr. G. Morvan, of 
New Jersey, U.S., for making transfers to lithographic stone, &c. A nega- 
tive being obtained from the design, it is printed by light on paper prepared 
as follows : — A suitable paper, albumenised or not, is placed in a] bath of 
sour milk, for the purpose of giving it greater strength and solidity. When 
taken from this, it is allowed to dry at an ordinary temperature, and is 
coated with the following material : half a pound of French glue dissolved 
in a pint of water, added while boiling to a solution of one-third of an ounce 
of permanganate of potash in a quart of water, and used cool. The paper 
thus coated is dried in the dark, and exposed under the negative. After 
removing, and before developing, cover the first coating with another com- 
posed of equal parts of bitumen, white wax, and Burgundy pitch, dissolved 
in a sufficient quantity of essence of lavender to allow of its being spread 
smoothly over the surface. Let this also dry in the dark j after which place 
it with the black side upwards in a bath of cold water, which dissolves 
those parts on which the light has not acted, and carries with it the super- 
incumbent mixture of wax, bitumen, and Burgundy pitch. The proof is 
finished by a few strokes of a sponge, and, when dry, can be transferred to 
lithographic stone, or to zinc or other metal, by contact and pressure in the 
ordinary manner ; to be printed from, if on stone, and to be engraved with 
acids on the metal, the composition protecting the parts it covers from the 
action of the etching fluid. 
Photography by Artificial Light. — Professor Falkland, in the course of 
some lectures on coal gas, delivered at the Royal Institution, pointed out 
the value of a new and intensely brilliant light to which photographers have 
recently had their attention directed, as being very actinic and manageable, 
and in other ways peculiarly fitted for photographic uses. Bisulphide 
of carbon warmed until it gives off vapour freely, is ignited, when it burns 
