The Acme line of microscopes was first introduced in 1879 by the firm Sidle and Poalk of Philadelphia. The microscope shown on this web page is an example of one of the first microscopes made by this firm. It was called "The Acme". By 1880, the firm was located in Lancaster Pennsylvania under the name John W. Sidle & Co. or the "Acme Optical Works". Subsequently, the entire output of the Acme factory was consigned to the retailer and manufacturer of scientific instruments, James W. Queen of Philadelphia. Later examples of microscopes from the Acme Optical Works can be found on this website.

Reversible horseshoe base

From The Journal of the Royal Microscopical Society, pg 523, 1880

Sidle and Poalk's Acme Microscope.—This Microscope, shown in Fig. 39, is the first cheap instrument that we have seen with a swinging substage.

The general form of the instrument hardly needs any description, but it may be mentioned that the stage is made of two thin, circular brass plates, the upper one (shown in the lower left-hand corner) fitted to turn upon the lower, so that the object can be rotated in the field of view. The stage can bo centered. The upper plate can be removed, and two spring clips attached to the lower one, either above or below, thus making a stage for use with oblique light. The aperture in the stage has a standard-screw thread, to receive various accessories for illumination when it is desired to have the mirror move independently of them, and also to afford a means of mounting the selenite so that it can be revolved without turning the Nicol prism.

The mirror and substage are both attached by sliding fittings to the same bar, which carries them around the object as a centre. The circular piece at right angles to the stage, gives steadiness to the bar, wiith smooth movement, and is graduated to show the angular direction of the illuminating pencil.

The horseshoe base is reversible, so that greater steadiness can bo ensured when the stand is used in a horizontal position.