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circa 1885, onwards


Watson VI

Watson VIWatson VI This vertical illuminator came in a can engraved on the lid: 'VERTICAL ILLUMINATOR, W.Watson & Sons Ltd., 313 High Holborn, London'. It was first announced in the 1885 JRMS, p 522. It is an improvement in the Beck version, offering a total of three different aperture diameters. The largest aperture is used by pushing the diaphragms aside and is simply the hole in the illuminator. The triangular piece offers two other smaller apertures to choose from. This improvement in the Beck model was the earliest to offer different apertures for the entering light built in to the illuminator. Like the Beck version, the coverslip can be replaced or removed for cleaning by turning it to the horizontal position and pulling out the knob holding it.

Later, more sophisticated designs eventually included a miniature continually adjustable iris diaphragm. A further improvement was to include a built in lens to concentrate the light onto the reflector. Prisms were also sometimes used as the reflector. All of these features are incorporated into the Watson Combined Vertical Illuminator, which gives the option of using a prism or a coverslip as a reflector, while at the same time incorportating the other improvements.