88 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
(2) The base is double ; the upper plate, carrying the standards of 
the Microscope and of the micrometer, rotates on the lower on a centre 
in the line of the optic axis. 
(3) The mirror is attached to a rotating cylinder in the centre of 
the lower base-plate by two elbow joints set at an angle, by which it 
can be adjusted at any angle in altitude beneath the object, whilst main- 
taining very nearly an equal distance from the object in all positions. 
The mirror can thus be rotated radially upon the object, or vice versa. 
The example of this second form of Nobert’s Micrometer-Microscope 
in Mr. Crisp’s collection is furnished with a mechanical stage (with 
glass surface) in which the rectangular movements are effected by means 
of a single plate. Fine micrometer-screws are applied to project from 
two right-angle edges of the stage and pass through fixed shoulder- 
rings ; each screw has a spiral spring encircling it and pressing against 
the shoulder-ring ; milled nuts exterior to the shoulder-rings act on the 
micrometer-screws, giving very smooth and delicate rectangular move- 
ments to the stage. 
Old Microscope with nose-piece for rapidly changing objectives 
and mirror formed of a silvered bi-convex lens.— The nose-pieces of 
which so many were brought out a fe w years ago for rapidly changing 
Fig. 3. 
the objectives were generally considered to represent an entirely modern 
idea, tliough our forefathers had placed objectives in a long dove-tailed 
slide like fig. 3, or more commonly in a 
Fig. 4. 
rotating disc like fig. 4. 
An old Microscope recently acquired 
by Mr. Crisp (shown in fig. 5) has an 
arrangement which is doubtless the earliest 
of its kind. To the body-tube is screwed 
a nose-piece, to which is attached a short 
arm, on which 25ivots a second arm with a 
“cell” at the end, into which the objec- 
tives drop. To change the objective the 
second arm, which has a slight amount of 
“s|n’iug,” is depressed and then swung 
away from the body-tube, the objective 
lifted out of the cell and another inserted 
in its place, and the arm turned back again. The cell, which is ab ut 
1/8 in. deep, fits over the end of the nose-piece, and thus keeps the 
objective in j)osition. 
The Microscope is apparently of Augsburg make, probably by G. F. 
Brander, whose career as a mechanician and optician was comprised 
between the years 1734 and 1783, when he lived at Augsburg. The 
mirror is a biconvex lens silvered — a device which has been reinvented 
more than once during the last ten years ! 
