676 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the earliest known example of a slide-clip, as distinguished from the 
spring, plates, &c., in vogue at that time. 
This model has played an important part in the evolution of the 
Microscope ; for it was copied in 1771 by Adams, who added a rack and 
pinion to the forward movement of the body over the stage. It was also 
the type copied by Baspail for his Microscope, which seventy years 
later was very popular in France. 
Notes. — (a) The lateral movement of the stage may be- considered as 
a modification of the stage of Benjamin Martin’s “ Universal Microscope ” 
(1740). 
(6) The forward movement of the body over the stage is effected by 
a sprung slide. 
(c) The manner of clamping the slide to the stage is the same as 
that still employed by Powell in his iron Microscope, and is the proto- 
type of the spring-clip at present so largely used on Continental Micro- 
scopes. 
(d) This instrument is the earliest known example of a pillar, 
mounted excentrically, and rotating on its foot to increase the stability. 
This idea was copied by George Adams in 1771. It was reinvented by 
Mr. A. McLaren.* It has also lately been introduced by Messrs. Boss 
& Co.j It ought to be pointed out that the pillar of John Marshall's 
Microscope, 1704, was also mounted excentrically, and was capable of 
rotation, inasmuch as it had a ball-and-socket joint at the bottom. 
This, however, was not meant to increase the stability, but to swing the 
Microscope clear of its base, which was necessary for purposes of illumi- 
nation, there being no mirror. Stability in John Marshall’s Microscope 
was obtained by fixing lead to the bottom of the box. 
Speaking to-day with our fuller knowledge of the essential points 
of a Microscope, we should severely criticise Cuff’s Microscope. The 
attachment of the stage to the pillar by a pivot cannot be commended, 
neither can the hinged joint on the limb which carries the body. Both 
these devices deprive the instrument of all steadiness, and render it fit 
for work with the lowest powers only. The designer evidently thought 
that the transverse motion of an object was better secured by a pivoted 
stage than by the pushing of a slider between two plates compressed by 
a stiff spring ; in this he was probably right, for we must compare the 
instrument with those in use at that time, and not with our modern 
stages. The hinged joint in the limb was to allow the Microscope to 
be placed in a horizontal position, so that any object held in the stage 
forceps might be examined with a Lieberkuhn with direct illumination, 
which was a method much in vogue at that time. In brief, it was a 
throw back on what has been termed “ the telescope mount.” 
The probable date of this instrument, w T hich is signed, is circa 1760. 
(2) Eye-pieces and Objectives. 
Improved Huyghens Eye-piece.J — Ur. Hugo Schroeder begins a dis- 
cussion of the principle of this eye-piece by pointing out that, as is well 
* Journ. R.M.S., 1884, ser. ii. vol. iv. fig. 9, p. 111. 
t t Jtmrp. R.M.S., 1894, pp. 507-8, fi^s. 39 and 40. 
X Central-Ztg. f. Opt. u. Meek., No.Ao, May 15, 1898, pp. 91-3. 
