Stand la (Fig. 15). A large instrument suitable for the majority of special requirements and adapted for all our accessory apparatus. The upper body is inclinable from the vertical to the horizontal position and may be fixed in any intermediate position by means of a clamping lever.
Coarse adjustment by rack and pinion, fine adjustment by micrometer screw with divided head (vid. p. 33)
Abbe illuminating apparatus vertically adjustable as a whole by rack and pinion movement. Condenser system of 1.40 num. apert. which may, by means of a small lever projecting from under the left side of the stage (not shown in fig. 15), be swung out of its central position so as to facilitate rapid transition to illumination with the cylinder diaphragm. The latter is made in the form of a cylinder fitted with an iris-diaphragm; it is fixed to the condenser and the latter may, by means of a small milled head projecting from the iris collar, be closed and opened (vide below No. 105, p. 61). Below the condenser is the iris-diaphragm, which by a rack and pinion moves out of the centre and may also be rotated about the axis or entirely swung out.
The circular object stage of 120 mm = 48/4 in. diameter rotates about the optic axis and may be centred with respect to the latter by means of two milled head screws and a counter pressure pin.
The stand is supplied either with solid plain vulcanite or instead of the latter with our new large mechanical stage (vide Zeitschr. f. wiss. Mikrosk. Vol. 11, No. ,3)
The available lateral movement measures 50 mm = 2 in, and the stage moves through 35 mm = l 1/2 in. the direction from front to back. The amounts' are read by verniers and scales.
Our new mechanical stage is so solidly constructed that possessors of a stand fitted with it may well dispense with the plain vulcanite stage. The mechanism (L K) which serves for the lateral movement of the object lifts off after unscrewing the fixing screw L, whereby the solid lower part of the stage becomes free. By means of the milled head W this lower part of the stage can be made to move in a forward and backward or if the whole stage be rotated in any other desired direction. The mechanical stage is readily replaced by the plain stage by turning the centring screws back and pressing the stage while still attached to the stand forwards against the buffer-pin, when it easily lifts out of its seat. The other stage is attached in a precisely. similar manner.