The instrument has the serial number of 1017 imprinted on the floor of the original case (as was usual in those years) and a rare type of gliding stage attachment. B & L started to manufacture microscopes under their own name in 1876, and this microscope is from the first few years of production, and almost certainly, the first year in which this model was made. This model has the gold-painted base with the rest of the microscope in lacquer except for some parts of the stage painted black, and the silvered scale and the (single) nickeled draw tube, a portion of which is seen in the photos. The company advertised a double draw-tube but this had not yet been incorporated into this earlier version. The gold painted flat tripod foot (base) was often found on earlier models while the lacquered base (or foot) appeared on many of the later versions. The instrument comes with its original case, but no key, one eyepiece, two objectives, and a vulcanite (hard rubber) substage condenser housing using one of the objectives as a condenser, as was typical for very early microscopes. The condenser slides into a black-painted sliding condenser holder. The mirror slides up and down and in addition has an extension allowing it to pivot as well. At first glance, the calibrated scale might suggest it was for measuring obliquity of the substage, but in reality, although the mirror assembly can move, the substage itself is fixed. The calibrations were for the stage itself which is shown in its tilted position in the photo on top right. In order to tilt the stage, a screw which fixes it in the horizontal position must be removed. The thin stage has a glass surface with a glass-supported gliding slide-holder. This type of glass gliding slide holder is much less common on the B & L stands than on other maker's stands of the same era, but B & L advertised that a stage such as this could be attached to the standard stage selling it for an extra $5. Later on, a thicker stage with gliding slide carrier was used. This defeated some of the advertised advantages of the thin stage in this model.
The outfit includes:
HISTORY OF THE INVESIGATOR MICROSCOPE
The investigator stand was first produced c. 1879. It sold with 3/4 inch and 1/5 inch focal length objectives in the Walnut case for $75 or $80 with a gliding glass stage. It was a moderately priced instrument and was quite popular, evolving through at least three versions over the years. Its popularity stemmed from the minimal advantage of the more expensive Physicians model and because of its lower price, the Investigator model was more likely the choice of many doctors
