American Microscope Makers

Bulloch’s Newer Congress Stand

From the Journal of the Royal Microscopical Society, 1882

This is made upon the original plan, with the exception of the stage, the construction of which has been modified. The stage is held by a saddle-piece which is steadied by a strong brace passing down from the limb. It is entirely independent of the swinging of the mirror and substage. This saddle-piece contains a set of screws with perforated heads for centering the ring which supports the stage. These screws are so far back that the ring can be made very thin without reducing the strength or rigidity. The stage rests upon this ring. It rotates, and can be accurately centered by the screws in the saddle-piece.

This stage is a revival of an idea which Mr. Bulloch says was used by Spencer thirty years ago. It consists of the ordinary stage-plate, having in its centre a large square hole. One side of this plate con- tains a wide dovetailed groove, in which slides a bar with its surface level with the top of the plate. At right angles to this bar is attached another bar. On this second bar slides a third bar, into which it has been dovetailed. The motion of this third bar is at right angles to the motion of the first. A thin plate is attached to the third bar, and lies flat upon the stage-plate. This plate is perforated, and holds the slide by means of a spring. It will be seen that this arrangement permits of motion of the thin plate in two directions at right angles to one another. Two pinions, perpendicular to the stage, control this motion; they work one through the other, and act upon racks placed at right angles. Scales placed at right angles serve as finders.

The substage is similar in design to that of Messrs. Sidle, and a screw has been added to the base for clamping the base-plate which rotates on the tripod.

Walter H. Bulloch

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