DESCRIPTION:

This uncommon microscope, often confused with the Beck 'Economic' model, arises on moderately short single pillar from a flat tripod to an inclination joint. The continental limb attaches at its bottom to the sector and thin stage. The large sector is calibrated 0 to 90 degrees on each side, with divisions every five degrees and numbers every ten. An adjustable pressure pin support screws into this sector to allow a gliding slide support to be used. The large but thin circular stage has a large diameter central opening. The underside of the stage is covered with a slightly raised, polished black hard rubber material (Ebonite) to facilitate use of slides on that surface. (A slightly lower serial numbered stand has no rubber on the bottom of the stage which is instead painted black.) Two holes on the stage allow the use of stage clips with long pegs either from above in the traditional manner, or below on the underside of the stage, thus allowing even more oblique illumination. The single tailpiece rotates through the axis of the stage, and can rotate above the stage for top lighting. On it is a sliding condenser fitting and below that a sliding support for the plane and concave mirror attached by a gimbal.

The standard 'condenser' is nothing more than an aperture, but can be removed to allow use of a more sophisticated lensed condenser, as shown to the right. There is a single objective and single ocular.

The main optical body tube has straight rack and pinion coarse focusing, and fine screw fine-focusing through the continental limb. There is a single draw tube (left), which has calibration markings every inch. The nosepiece is not sprung.

In addition to stage clips, a sliding glass slide support was supplied as an option and is shown here with the instrument. The glass slide-holder has a central opening the same size as the brass stage. The edges of the glass are are beveled. The brass part of the glass slide support has angled grips, dovetailing into the beveled edges of the glass. This brass part can be tightened or loosened by knurled knobs, securing the brass to the glass. Each of these knobs has a hole for accepting a stage forceps. A large rectangular cutout in the brass allows the pressure point to work on the glass surface. The knurled knob that engages the glass slide support has an ivory tip. The pressure can be varied to allow the glass support to slide easily or be held in a stationary position. On the slide support is a small single stage clip on the right, and a stop on the left for registering the edge of a slide or Maltwood finder. Two of the middle images above show a comparison of the 'Ideal' with the 'Economic' model; click on those images for an enlarged comparison.

HISTORY OF THE IDEAL MICROSCOPE

This model, called the 'Ideal' model, was first reported and figured in the 1881 volume 5 of the JRMS, on pages 805-807. It is sometimes confused with the simpler and much more common Beck 'Economic' model, which does not have a sector substage, and is shown in comparison above and also on the Ideal and Economic Comparison page. This microscope incorporates a swinging tailpiece, the angle of which registers clearly on the 'sector'. A similar microscope was also made by Sidle and Poalk (after suggestions from J. E. Smith at the Microscopical Congress of 1878) marketed as the 'Acme' brand and a later modified version as the 'Acme No. 3' sold by Queen and Co. Interestingly, the suggestion of putting the stage clips under the stage to allow further oblique illumination than possible when the slide is on top, was also a suggestion for the original Acme microscope (as described by JE Smith in 'How to See with the Microscope, 1880). A similar sector microscope was also made by Robert Tolles. Many other makers produced the swinging substage in other variations, and examples on this website which either have the degrees engraved on the edge of the rotating ring, or simply rotate with no calibrations, include those by Bulloch, Bausch & Lomb, Ross, Zentmayer, and others.

The first person to popularize a method in which the swinging substage did not have to be refocused as it swings, was the famous American microscope maker, Joseph Zentmayer. By having its axis of rotation at the plane of the slide, the substage condenser focus was maintained throughout the range of obliquity; ironically, the condenser focus often could not be maintained due to obstruction by the stage. Zentmayer received his American patent for this design in 1876. This design was swiftly copied by several English and American makers as seen here. The craze for extreme oblique illumination via a swinging substage continued for a relatively brief period of time. Perhaps the most extreme version of oblique illumination can be seen in the 'Radial' microscope made by Ross (under Wenham's direction). This method of oblique illumination was soon abandoned in favor of much simpler methods such as using an offset of the condenser or a stop with an offset opening. As mentioned above, some models had the underside of the stage simply polished and painted black while this example had a piece of polished hard rubber on the bottom surface; either would suffice to hold a slide under the stage for maximally oblique illumination.

Parenthetically, the concept of a gliding slide-holder with a glass surface on which the pressure pin registers, was also the invention of Zentmayer. In its original form, the slide support was made of brass with only the 'window' being made of glass, contacting the pressure pin. This contrasts with the Beck design where the majority of the stage is made of glass with a brass piece attached. The original form of that stage can be seen on the 'Grand American' Model in this collection.