798 
A NEW FORM OF POCKET MICROSCOPE. 
scopic investigation being conducted with as little delay as 
may be. 
Objectives of high magnifying power are indispensable in 
the examination of morbid products; the problem, therefore, 
to be solved was the construction of an instrument of small 
size and simple mechanism, capable of magnifying at least 
six hundred diameters. The solution of the problem is fur¬ 
nished by the little instrument which is depicted in the 
illustration. The microscope was made, under my direc¬ 
tion, by Mr. Swift, optician, of University Street, and an¬ 
swers the intention in a most admirable manner. I did not 
doubt that I should obtain a very useful instrument, but I 
did not anticipate results so entirely satisfactory as those 
which have been obtained. The movements, both coarse and 
fine, are perfect; the definition of the objectives, the inch, 
fifth, eighth, and twelfth, is exceedingly good; and the work¬ 
manship is excellent. The principle of the short body, with 
deep eyepiece, has been worked out completely, and after a trial 
of several weeks, in various places and under all sorts of dis¬ 
advantages, it is satisfactory to be enabled to say that in 
practice the microscope leaves nothing to be desired. 
A short body naturally involves a loss of amplification,which 
must be compensated by a deep eyepiece; for instance, the pre¬ 
sent instrument of three inches in length, with an E eyepiece, 
may be estimated to magnify, with the same objectives, about 
the same number of times as a microscope with a ten-inch 
body would with an A eyepiece, while the deep eyepiece has 
the further advantantage of acting as a very sensitive fine 
adjustment, by merely altering the position of the draw tube, 
in which it is inserted. 
The small instrument which I have used in the fields, 
shed, or room, in a railway carriage, and on the top of an 
omnibus, is provided with an inch, a fifth, and an eighth ob¬ 
jective, the latter with an immerson lens, giving the mag¬ 
nifying power of a twelfth. It has also three eyepieces com¬ 
mencing with C, but the one which is most effective to 
general use is E. 
A polarizing apparatus and other appliances can be added 
if required. When closed the microscope, as shown in Fig. 1, 
is a trifle over three inches in length, and one inch in dia¬ 
meter in the largest part. The box which carries the objec¬ 
tive and eyepiece slides smoothly in a tube (a, Fig. 2), on 
which a box (b, Fig. £), containing a spiral spring and an 
accurate fitting plug, forming the stage, is screwed. The mirror 
is held by a pin which passes through a hole in the lower 
part of the stage, so that it can be arranged at any distance 
