FOR THE ADVANCEMENT OF SCIENCE. 515 
for— except by teachers. He had used it for years in teaching, but not 
much as a ‘‘clinical.” A glass slide to hold the object, with a thin cover 
laid on by capillary attraction, is well for once, but does not satisfy a 
busy man. It applies to too limited a range of objects; and the cover is 
inconvenient to carry, awkward to handle, and easy to break. He had 
used Wenham's compressor until lately, but that is inconvenient under 
the springs of the “clinical” stage. The new compressor, figured below, 
is simple (and d inexpensive) and can be used with great bes 
both for clinical and class use, and for much of the ordinary work of th 
microscopist. It is E except upon a large stage, in hii case 
it would require a few pins to serve as legs. The want of parallelism is 
less than in most compressors, and is not inconvenient in clinical use. 
The two brass plates seht entirely for apto the object or clean- 
ing the glass. The upper plate fits into a notch filed in a ledge at the left 
of the lower, the Prata of the two plates ss secured by a pin 
through the lower and a notch in the upper. The screw which attaches 
them at the right is permanently fastened in the upper plate by a groove 
‘sia a pin. It has a coarse thread, which may be cut double to screw out 
. more rapidly, or — AG may be reversed near the centre so that it will 
at the same tim e the upper se depress the lower plate. Should a 
steadier motion [n pecus a spring may be riveted upon one plate to 
press against the other. The rie i is adjusted for a glass of 1-20 
Fig. 101. 
mess 
Ward's Clinieal Compressor. 
inch below the object and 1-125 above, cemented upon the inner surface of 
the brass plates. This is strong enough to carry in the pocket safely; it 
can also be used with the parabolic illuminator, or with any objective or 
achromatic condenser except those of large angular aperture. uld 
thin glass be required for any purpose, a glass or tin cell of sufficient 
thickness to e putres should be cemented on one of the 
plates, or both if necessary, and the thin v fastened upon the rim thus 
form Should no cell of UE thickness be at hand, select a glass 
cover of the required thickness, fasten i iih marine glue on one of the 
plates, punch out with a file the part corresponding to the opening in the 
plate, and then fasten the thin glass with Canada balsam upon this extem- 
zed 
Ti Mw 
Mr. E. B. Benjamin, of New York, exhibited a microscope by Gundlach 
of Berlin. This was a sma cheap instrument, according to the 
