220 
POPULAR SCIENCE REVIEW. 
high by three inches wide. It is an instrument which no one who works at 
the microscope should he without. The following is the account of it given 
by the maker, and we can fully bear out its accuracy : The metallic chimney 
being telescopic occupies a very small compass ; the condenser fits into the 
cell in front, which is also provided with plain and tinted glass for correct- 
ing the colour of the flame. The reservoir is of brass, and will contain suf- 
ficient petroline for six hours’ consumption. The entire lamp fitting into 
the case from the top, escape of the oil is prevented. In trimming the lamp 
care should be taken that the wick is perfectly dry, and the petroline of 
good quality ; also that none of the oil gets upon the metallic chimney or 
reservoir, or a bad smell will be given off until the oil is burnt away. In 
using the lamp it will be found convenient to slightly incline it, so as to 
bring the broad surface of the flame more parallel with the surface of the 
mirror of the microscope. When it is necessary to re-line the chimney, 
screw off the sliding portion, wash out the old lining, and re-coat it with 
superfine plaster of Paris. When dry it will be found ready for use — a few 
minutes will be found sufficient to do this. 
The American Journal of Microscopy is, so far as we have seen, a most 
inferior J ournal of general natural history. It is many miles behind u Science 
Gossip ” in point of matter. However, it may improve. 
The Aeroconiscope. — This name has been applied, we imagine, by Dr. 
Maddox. Through this instrument he collected the various germs which 
have been floating in the air for months. Some of the fruits of his re- 
search have been figured in two plates in the “ Monthly Microscopical 
Journal ” for February, but as yet a great number of the specimens obtained 
by him with the above instrument and figured in the Journal, are un- 
named. 
PHOTOGRAPHY. 
New Lens— A. new lens, of which great things are reported, has recently 
been brought out by Ross. Including the full pictorial angle of view, it 
possesses the further advantages of being quite free from distortion, work- 
ing with great rapidity, and having so much sharpness that a figure which 
was taken in the foreground of a landscape has been magnified up to a large 
size, the magnified photograph being quite sharp enough for pictorial effect. 
With a lens of this kind the tourist photographer has a great power, viz. 
that of being able to select and magnify any desirable object in the negative 
taken by him during his journeyings. 
Pocket Cameras. — The advisability of using very small cameras for land- 
scapes has been much discussed in photographic circles during the past two 
or three months. It is well known that from a very small negative an 
enlarged print may be obtained, the degree of enlargement depending upon 
two things — the nature of the deposit that forms the image in respect of its 
fineness and delicacy of gradation, and the sharpness of the picture. Now, 
in consequence of an inexorable law in optics, it is impossible to obtain 
definition of the highest class over more than a very small space in the 
centre when a flat plate is used on which to take the photograph, for in 
flattening the field of a lens intended to work with a large aperture an 
amount of astigmation is introduced which is quite fatal to sharpness. Now, 
