246 MICROSCOPY. 
pressor unless moving too stiffly for ordinary use, and unavailable 
where objects are to be dissected and afterwards drawn with the 
camera or examined with high powers without risk of losing the 
object. Hence, for a working instrument, Prof. Biscoe prefers to 
discard the object carrier altogether and place the slide or other 
support directly on the stage. This is held in position, if the in- 
strument should be tipped, by a brass sliding bar held by two 
cranked arms capable of being instantly made to move more or 
less stiffly by means of screws with milled heads. Should it be 
desired to place the instrument horizontally, for camera work or 
photography, an extra piece of brass clamps the object in place. 
In Zentmayer’s new form of students’ microscope the glass slid- 
ing stage or object carrier is replaced by a glass sliding-bar, which 
simplifies the work and reduces the expense as well as secures 
some of the above advantages. 
Some object carriers are arranged, and all should be, except in 
either mechanical stages or very cheap work, so that the sliding 
movement can be easily controlled by the pressure of milled-head 
screws. h 
Nosert’s Lives. — Nobert has made for President Barnard a 
two hundred dollar test plate, twenty-band, which claims to reach 
224,000 lines to the inch, being twice as fine as the finest lines on 
the nineteen-band plate. This puts, him far ahead of the opticians, 
and he claims to be prepared to do still better when they overtake 
him. Who will make the first lens capable of resolving the twen- 
tieth-band? Or will those who believe they are able to resolve 
diatom-markings of equal fineness show it to us now? 
RESOLVING-OBJECTIVES.—The editor of the ‘Cincinnati Medical 
News” draws very strongly, not too strongly, the distinction 
between oe and those suitable for other work. 
He has a Powell & Lealand’s one-sixteenth which he finds quite 
useless except rs resolving diatoms. We mainly value, at pres- 
ent, the resolution of the famous tests as showing the achievement 
of a nicety of correction which can be, and should be, applied to 
the lower-angled working lenses. - 
Microscoric Writtnc. — This hitherto rare curiosity is now 
available to all microscopists, both as an elegant toy and as a use- « 
-~ ful test for the optical qualities of their lenses. The following 
account, from a paper read before the Queckett Club, gives a view 
