ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 125 
metal plate-foot. This instrument had an archaic look on account of 
the plate-foot, but it was possible to fix an approximate date by the 
names “ Hartnack and Prazmowski ” which were engraved upon the tube, 
Mr. Prazmowski having joined the firm of Hartnack in 1862. There 
was also another point about this Microscope which helped to fix its date, 
and that was the Society’s screw, this screw having been introduced on 
November 12, 1857. With regard to the horse-shoe foot, this was 
adopted by Oberhiiuser at the instigation of Mr. Abraham, a Microscope- 
maker in Liverpool in 1847. This Microscope showed therefore a rever- 
sion to the old type. 
The next Microscope (fig. 2) possessed a rare form of Powell and 
Lealand’s fine adjustment. It would be remembered that the first adjust- 
ment introduced by Mr. Powell was a stage adjustment ; a Turrell stage 
was raised by means of three 
inclined planes below it, which 
were moved by a fine screw 
with a divided head like that 
of a micrometer, each division 
equalling the 1/6000 in. The 
date of this was 1833. The 
Society purchased one of these 
Microscopes in 1841, and this 
instrument was upon the 
table before the meeting. Mr. 
Powell then, in 1841, altered 
the entire form of his Micro- 
scope, by copying the Jackson 
model, and by adding a very 
perfect form of fine adjust- 
ment consisting of a cone ad- 
vancing by means of a fine 
screw. It was this kind of 
adjustment, the slide on the 
Jackson limb, which was so 
largely employed to-day in the 
Microscopes of Messrs. Baker, 
Beck, Swift, and Watson. Mr. 
Powell’s next idea was to adopt 
the bar movement, the fine ad- 
justment being a long lever 
of the first order as used at present, but it was interesting to note 
that the side screw was retained, the Microscope now exhibited being 
an example of this rare form. This Microscope was dated 1846. Very 
soon after this the fine adjustment screw was placed in the vertical 
position it still occupied. He believed that the screw was first placed 
in the vertical position on the portable Microscope, and he thought it 
would be found so figured in the first edition of Quekett in 1848. The 
bayonet-jointed cap to the eye-piece was also a feature of this instrument. 
The President also called attention to an interesting old Culpeper and 
Scarlet Microscope (fig. 3), which differed slightly from those in the 
Society’s collection, three of which were on the table for comparison. The 
Fig. 2. 
