Many of the accessories are made of hard rubber. This is a characteristic of the earliest B&L instruments. This microscope was designed by Ernst Gundlach while employed by Bausch & Lomb. The low serial number (76), which is stamped on the inside bottom of the case, indicates that this instrument was likely manufactured in the first or second year of production. Among the accessories are included four objectives with canisters, three hard rubber eyepieces, a sub-stage polarizer, an analyzing prism which mounts above the objective, two hard rubber diaphragms that mount upon the mirror, a sub-stage adapter that will allow an objective to serve as a condenser, two sub-stage condensers, a camera lucida, and a Botterill trough for live specimens. Also included are two sub-stage aperture wheels, one for bright field and the other for dark field use. The brass slide carrier can be detached and replaced with the two provided stage clips. These accessories are stored on the door of the storage case in addition to an internal drawer.
Extracted from the 1879 Bausch & Lomb Catalog:
PROFESSIONAL MICROSOPE.
The leading idea in the
construction of this microscope was to furnish at a
moderate price an instrument suitable to the
application of a variety of accessories, desirable in
many operations of the microscope, thereby enabling
the operator to perform a variety of microscopical
work for which our lower priced instruments are
inadequate.
It is provided with a
heavy brass foot, highly finished, inlaid with three
soft rubber pads at the under surface, and two solid
brass pillars supporting axis for inclination of the
body. Two strong screws with milled heads, placed at
the ends of the axis, serve to tighten or loosen the
connections by means of which the arm can be made to
move with more or less ease.
Coarse adjustment by
rack and pinion, moving a long prismatic slide
accurately fitted, attached to the body, and arranged
for compensation of wear. Fine adjustment by
micrometer screw, with milled head, silvered and
graduated, acting upon our patent movement described
in preface.
Glass stage with slide
holder similar to that described with microscope No.
540, but is of larger dimensions, circular in form
not shown in cuts, and fitted to receive the
hemispherical immersion condenser. In this stage we
gain thinness, while still maintaining its
stability.The slide carrier moves in any direction,
and also revolves.
Substage and mirrors
(plane and concave) are fastened to swinging mirror
bar, the axis of which is fixed in the plane of the
object, thereby permitting the accessories and mirror
to swing concentrically around the object. The mirror
may be brought to any obliquity and swung above the
stage for the illumination of opaque objects. The
mirror as well as the substage, can be moved on the
mirror bar to and from the object, and both can be
removed altogether, in an improved manner not shown
in the illustration.
The substage ring
receives the revolving diaphragm, condenser, etc.,
and auxiliary ring with internal society screw, which
accompanies the instrument, and to which objectives
and other auxiliaries may be fitted.
The history of the development of this microscope is described in the article:
The Bausch & Lomb Optical Co.s Professional Model Microscopes. 1876-1896
