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PATENTED FOOTPLATE FOR COOKE-McARTHUR MICROSCOPE

The foot plate of this microscope was described in detail in the original British patent referred to on the microscope. The foot plate grips the optical prism assembly ('optical tube')via recessed screws set into the side of the footplate. The foot plate and prism assembly then attach as a single unit to the underside of the microscope, via gripping screws protruding from the side of the microscope. There are four threaded openings on the bottom of this foot plate, and two threaded inserts or bushings, which can be moved to any of the four openings. The inserts themselves have slots to allow their removal by a coin. The inserts are threaded to accept the two different tripod mounts of the time, although nowadays there is only one commonly used. The center of the foot plate is recessed, a feature designed to avoid scratching the mirror surface when stored there.

According to the patent and the accompanying drawings, there was also provision for these threads to accept other accessories for storage, such as a condenser; this provision included a notch for the pin on the condenser, and this notch is not present on my example. Also noted in the patent is the presence of pins on the side of the footplate to allow the mirror or electric illuminator to be stored on the bottom of the microscope, or used to illuminate an opaque specimen from below, using the special optical tube. This facility of using the illuminator from below or for storage is shown in the accompanying images at the bottom of this page. Another provision referred to in the patent was the recessed center of the footplate as seen here, and also a dovetail slot in the recess to allow filters and the like to be slid into it for storage; the dovetail slot is the second feature in the patent lacking on this example, the center is simply recessed without the dovetail.

The Cooke-McArthur Tripod is pictured and described in the patent, but no claim for its invention was made by the Patent. For its size, this is one of the most stable tripods ever devised. Why it is not made today is a mystery to me!