14 BecKj on the Universal Achromatic Microscope. 
120, 180, 480, and 720 ; besides these, a third eyepiece may be 
added, which will as nearly as possible double the power of 
the first. 
That which we believe our customers will first ; 
selves of is a body as shown in PI. VI, fig. 1 ; this is so 
combined as that three object-glasses and three eyepieces 
shall be attached to it. Only one of each of these can be 
central with the axis of the body at the same time ] but any 
of the others can be brought into their proper position by 
pressing in the rounded head of a pin, (b), when either of the 
discs, (c), can be turned in the required direction, and will be 
stopped again by the pin, (b) , springing out. 
This will be a great advantage to those who are deterred 
from making a casual use of the microscope by the trouble 
first of all, of putting the instrument up, and, secondly, the 
delays which are caused by the necessary changes ; whilst it 
will considerably assist in the investigation of objects which 
are undergoing a change, either in their position or their 
structure, and when a great range of power is required with 
the least delay possible. As a luxury, it will apply to every 
use of the microscope. 
These remarks apply more especially to the change of the 
object-glasses; in some cases the eyepieces are to a slight 
extent in the way, as in using a camera lucida, whilst they 
are always more or less likely to be condensers of the breath; 
and as their change can be made rapidly, we have for these 
reasons, combined with a complicated structure that Avas 
involved, omitted them in the binocular edition. (Fig. 2.) 
From the very first glance through Mr. Wenham^s last 
binocular arrangement we have always been convinced, not 
only that this improvement was essential, but also that it 
must become universal. We have no cause, more than any 
other opticians, to urge the necessity of stereoscopic vision 
in nearly if not all microscopic investigations; and by bring- 
ing before you this evening a plan by which we hope to 
reduce the price considerably, we cast in but a very small 
mite compared with the liberality of the inventor, who, 
refusing the least emolument, has presented you with his 
scheme unpatented. 
PI. VI, fig. 2, shows the double body, and it possesses 
the following advantages : — the object-glasses are mounted 
on a rotating disc, as already described; an adjustment for 
different distances between the eyes is made by sliding the 
draw tubes (e) up or down, the milled head (r) clamping them 
in any required position. Tlie reflecting prism is placed 
close behind the back lens of each object-glass, and with 
