Another highly-useful and more complete simple biology lab microscope was contrived by Mr. Valentine, and made for him by Mr. Ross in 1831. It is thus described by the latter gentleman, and is represented. It is supported on a firm tripod, made of bell-metal, the feet of which, are made to close up for the purpose of packing it in a box. The firm rises from the tripod, and carries the stage; this is further strengthened by the two supports. From the pillar a triangular bar, and a triangular tube, is moved up and down by a screw, having fifty threads in the inch, and turned by a large milled head, which is situated at the base of the pillar: this is the fine adjustment.

The small triangular bar is moved up and down within the triangular tube, by turning the milled head, forming the coarse adjustment: this bar carries the lens-holder. The stage consists of three plates; the lowest one is firmly attached to the pillar, and upon this the other two work. The upper one carries a small elevated stage, on which the objects are placed; this stage is mounted on a tube, and has a spring clip, for holding, if necessary, the objects under examination. By means of two screws placed diagonally, this elevated stage can be moved in two directions, at right angles to one another; and thus different parts of objects can be brought successively into the field view.

The arm, for carrying the lenses is attached to the triangular bar by a conical pin, on which it is made to turn horizontally, and the arm itself can be lengthened or shortened by means of the rack and pinion; hence the lens can be applied to every part of an object without moving the stage.

The mirror is fitted into the largest of the three legs, and consists of a concave and plane glass reflector. To the under side of the stage is fitted a Wollaston condenser; and the lens is made to slide up and down by means of two small handles projecting from the cell in which the lens is set. Two small tubes, with either a condensing lens for opaque objects, or a pair of forceps, may be attached to this side of the stage. The magnifiers are either simple lenses or doublets; or it could be easily converted into a compound microscope by inserting a compound body, supported on a bent arm, in the place of the one carrying the single lenses.