From The Journal of
the Royal Microscopical Society, 1882
Bausch and Lomb
Optical Co.'s Professional
Microscope. Fig. 113 (cut from America, is one
of the best woodcuts of a Microscope which we have
seen) shows the "Professional" Microscope of the
above Company. Its specialities are the frictionless
fine adjustment (described at p. 683), the glass
stage and slide-carrier (described at p. 687), the
centering of the substage (of which we have no
detailed description), the two draw-tubes which allow
of more than the ordinary variatious of length, and
the mirror and substage bars which are separate and
can be moved independently of one another, or
simultaneously when the arm on the mirror is placed
in a recess in the substage bar.
Bausch and Lomb
Optical Co.'s Fine
Adjustment. Fig. 126 represents the original
of the fine-adjustment referred to at Vol. I. (1881)
p. 110. Two strong parallel blades of finely tempered
steel, a a, are securely fastened on one end to the
back of case Fig. 126. d, on the other to the arm e,
which carries the rack and pinion, b shows the
micrometer screw, which is fitted to the upper part
of the upright arm c, f is the pinion, g the
rack and slide, h the tube. Two screws fasten the
adjustment case d to the pillar c. An arm projects
from the part e and passes into a recess in the
pillar c. The springs support the entire body, and as
their tension is upward, the projecting arm bears
continually against the micrometer screw b, and it is
evident that tho distance traversed by tho screw
involves the same movement of the arm e, and
consequently the body. The only points of contact are
at the ends of the springs a, a, where they are
fastened respectively at d and e, and on the
micrometer screw, and as in the former there is
absolutely no friction, there is no wear; while that
which may eventually take place in the latter is
taken up by the force of the springs.
The points of
excellence claimed by the makers for this adjustment
over all others, are the following: 1. It moves the
entire body. 2. It is extremely sensitive and direct.
3. It has no lateral motion or displacement of the
image, while adjusting. 4. It has absolutely no lost
motion. 5. It can in no manner deteriorate.
Extracted from the
1892 Bausch & Lomb catalog:
Fine adjustment, Differential screw
Applied to any of our
instruments..............6.0
As applied to
instruments not made by us...8.00 to 10.00
As high power
objectives are in more common use than was formerly
the case, particularly in biological research, it had
been found that a more delicate movement than the
ordinary fine adjustments is desirerable, and the one
we now offer is the most simple as well as efficient,
and particularly valuable inasmuch as it can be
applied to almost every existi:ng instrument In which
the micrometer screw is attached to the arm. It is
put in connection with the micrometer screw, and
comes into play at will by tightening the thumb-screw
at the top. The one milled head operates one or the
other. It can be made to almost any degree of
fineness, but that which we have found most
desirerable is the 1/75 in for the fine, and 1/300 in
for the Differential Screw fine adjustment, for
revolution of the milled head.
The
Aug. 15, 1882 patent covering the differential screwwas granted to P. H. Yawman.