LARGE BINOCULAR COMPOUND MICROSCOPE: THE BAUSCH & LOMB CONDENSER ASSEMBLY

BAUSCH & LOMB CONDENSER AND CONDENSER MOUNTING ON THE DALTON MICROSCOPE:

The condenser on this microscope(A) is signed BAUSCH & LOMB OPTICAL CO.. It is attached to the B & L Condenser Mounting(B) as shown in the 1893 B & L catalog. The substage ring which holds the condenser mount(D) is centerable via two knurled knobs(C), 90 degrees apart from each other. The rectangular opening in the side of the square-shaped sub-condenser mount accepts a blackened brass slide(shown installed in the image above, and separately in the image at the bottom of the page). The brass slide was advertised as accepting a blue glass filter, dark field spots or aperture-adjusting inserts singly or in combination. The mount has a leaf spring with a tiny screw head which registers the thin notch in the center of the brass slide. This brass stop-carrier has a tiny handle on one side to facilitate its insertion, or position. In this particular outfit, the brass slide is an accurate modern replacement; there are three apertures, one stop, and a blue-green glass filter.

The ring holding the condenser assembly is attached to a stem with a narrowed part, that is held in place on the focusing piece by a knurled knob(E). It presumably could have been replaced by other accessory apparatus. This substage is focused by rack and pinion via the knurled knob F. This type of substage mount which can be removed by loosening the E knob was typical of the substages of other known BOW microscopes, including the B stands of the time of Tolles himself.