106 
POPULAR SCIENCE REVIEW. 
afford additional mechanical facilities. On a smaller scale the form of the 
letter N might he preferred. Attached to each objective should he a length 
of tube twice or more its focal distance. To avoid moving the body of 
the instrument, I would apply the adjustments to the stage. The experi- 
mental instrument of glasses described in 1863 performs admirably, on a 
white enamelled watch-case, on the surface of a flea, on solid deal, on 
mouse’s hair, and on the surface of the pollens of whin, broom, and geranium, 
without condenser. The field is remarkably flat, and available at every 
part.” 
Smith's New Growing Slide. — Dr. John Barker, of Dublin, has devised an 
ingenious modification of Smith’s new growing slide. It consists of a shallow 
glass box, as in Smith’s, but both upper and lower plate having cut out of 
each a circle of about an inch in diameter; and a piece of glass tubing 
set therein and cemented, so as again to hermetically close the box. Im- 
mediately over the aperture thus made through and through the box, a 
circle of glass, a shade wider in diameter and rather thinner than an ordi- 
nary slide, is cemented, thus again closing the aperture through the box at 
one of the surfaces. The upper surface of this circle of glass forms the table 
on which the object for examination is placed. At the right-hand side, just 
beyond the edge of this circle of glass, and near the lower edge of the box, 
a small hole is drilled through the upper plate of the box, which is the 
feeding hole for the water, which is introduced into the box by a small 
opening ground away at the lower right-hand corner. The object is now 
covered by a square of thin covering glass in the usual way ; one angle of the 
cover extends at the right-hand side beyond the circular table, and reaches 
so far as to cover the little feeding aperture in the box, and the flow is 
established. There is a little strip of glass cemented at the lower side to 
prevent the square cover slipping. This plan has the advantage of allowing 
the light to come up from the mirror, not through a stratum of water, how- 
ever thin, but directly through a thin plate of glass, permitting, too, the 
use of the achromatic condenser if needful. Dr. Barker stated he had found 
this plan to act very well. 
A Handy Cabinet for Microscopic Objects. — Mr. Collins, of Great Titch- 
field Street, has sent us a specimen of a slide-cabinet, which is certainly a 
marvel of simplicity, cheapness, and efficiency. It consists of a sort of card- 
board box provided with a cover, and whose front side, if we may use such 
an expression, lets down. Opening the box we see six neat papier-mache 
drawers, each of which contains six compartments for slides, which are laid 
upon the flat. The great advantages of this case are : the economy of space, 
the convenience with which any of the drawers may be removed, the ease 
with which the names of the various objects may be observed, and the ex- 
treme lightness and portability of the case. We believe the cabinet was 
originally designed by Mr. Piper, and we commend it to the notice of our 
readers. 
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PHOTOGEAPHY. 
Mr. Woodbury's Printing Process. — Certain of our contemporaries long 
since promised specimens of this new process, which have not up to the 
