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Sidle's "Congress" Turntable

From Journal of the Royal Microscopical Society,1881

Sidle's "Congress" turntable (so called from having been first exhibited at the "Congress of Microscopists" at Indianapolis) is here shown.

Into the upper surface of the rotating plate, and diametrically opposite and equidistant from the centre, are set two circular plates or disks, 1 inch in diameter, their surfaces flush with that of the large plate. Pivots from the two disks project through the plate, and each carries upon the lower side of the plate a toothed wheel. A hollow sleeve rotating freely upon the stem of the table carries a third and larger wheel, which gears into the two others and thereby gives rotation to the disks in the top of the plate.

Near the opposite edges of the two disks, the angular jaws which hold oppo site corners of the slide are pivoted (as in Cox's and other forms), so that by giving rotation to the central wheel under the plate, the jaws may he made to approach or recede at pleasure.

A coiled steel spring, concealed within the hollow sleeve, serves to close the jaws, while a single motion of the milled head upon the sleeve, opens them to their full extent; the lower milled edge serves to give rotation to the turntable.

Although the jaws do not approach in a straight line, yet when properly adjusted, a line joining the pivots of the jaws will cut the centre of the plate, whatever the position of the jaws, and they being always equidistant from the centre, it follows that the slide, when clasped between them, must he perfectly centered. For the purpose of retouching old slides the ordinary spring clips are retained.

An improvement has been made in the supporting stand, the iron tripod being now so arranged that the hind legs are removable and, being held in position by a clamp-screw, the same screw serves to clamp the instrument upon the edge of the work-table, should this mode of using it be preferred.

John Sidle other microscope makers

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