136 Chronicles of Science. [ Jan. 
A glance at the accompanying woodcut will greatly aid in the 
understanding of this mode of arrangement. 
The microscope, as is here seen, is fixed into the bottom of the 
mahogany box, which forms at the same time the stand. Round it, 
like the one previously described, which is in this respect made on 
Dr. Harley’s model, a groove is run to receive the lip of a glass 
shade. The instrument itself is made of polished brass, and is eighteen 
inches high. The eyepieces are supplied with shades (a, a) to protect 
the eyes. 
These are a great comfort to the observer when he is using the 
instrument for any length of time. 
At the end of the transverse arm (f), is the box which contains 
both Wenham’s binocular prism, and the analyser of the polariscope ; 
and by merely drawing it a little out, or pushing it farther in, the 
instrument can be instantly changed from a binocular to a uniocular, 
and still further to a polarising microscope. 
Immediately beneath (f) are the two objectives, a quarter, and an 
inch; so that in order to change the power, all that is necessary is to 
slide them backwards or forwards. Moreover, these are fitted with the 
universal screw, so that either of them may be detached, as in an 
ordinary instrument, and a }, as, or any other power, put in its place 
at the option of the observer. The instrument is fitted with a coarse 
