12 BecKj on the Utiiversal Achromatic Microscope. 
consideration of the whole as well as eacli individual part, we 
have in no instance made a sacrifice of efficiency for the sake of 
appearance ; but with this expression of our motive, we would 
also ask the casual observer to withhold his judgment until 
the working qualities and the price of the instrument are also 
before him. 
The foundation of the stand is a large, circular base (a), and 
near its circumference, on the left-hand side, is a strong 
pillar (b) ; at its top is the axis upon which the remainder of 
the instrument turns, and with so equal a balance as never to 
require more than a slight screwing down of the small, milled 
head (c) to secure any particular position. 
On the same centre as the axis is a large, milled head (d), 
by which a quick motion is given to the body (e), and depend- 
ing from the smaller part of the same milled head is a lever (f) ; 
this of itself hangs free, but when held at the end and pressed 
sideways, either nearer or further from the pillar, it obtains 
a gripe upon the milled head (d), which can then be turned so 
slowly as to constitute a very good slow motion.^ 
The quick-motion milled head and the slow-motion lever 
are always in the same position, and do not alter with any in- 
clination of the body they are also so low down; that in 
using them, the hands are very little raised from the table j 
this latter advantage also applies to the stage (h) which is 
screwed on at the lower end of the limb (g) at less than four 
inches from the bottom of the stand. 
On the top of the stage is a double spring (i), branching 
right and left over a brass plate (k). On this there is a 
ledge (l) for the object to rest upon, and in continuation, on 
the right-hand side the plate, is bent over, so that it may be 
firmly grasped by the fore and middle figures underneath 
and by the thumb above. By this arrangement the object can 
be moved freely in every direction, and will retain its position 
after the hand is Avithclrawn. If necessary, the short spring 
(m) may be used when the object has to be held firmly on the 
plate. The small pin (n) is for holding the forceps (o). 
Beneath the stage is a cylindrical fitting p, for all the appa- 
ratus required in that position. The diaphragm (q) is, however, 
made a fixture to the mirror-stem (r), except that it will turn 
away entirely on the left side when necessary ; it is provided 
with one small aperture (x) for the lower powers, and this can 
be closed, or otherwise by a small shutter (y) . 
A concave mirror (s) swings in a rotating semicircle (t), which 
* Mr. Brookes was, we believe, tlie first to recommend this kind of slow 
motion, and the chain motion ; and the chain movement, wJiich we have 
also adopted, has liitherto been chiefly confined to Mr. Lobb's instruments. 
