P & L NO. 1 MICROSCOPE: STAGE DETAILS
MAKER: POWELL & LEALAND
DATED: 1878
SIGNED: 'Powell & Lealand, 170 Euston Road, London' and also dated '1878'
The P & L Stage has a complete set of adjustments and is fully calibrated. The rotational movement is indicated on a scale engraved on a solid platinum plate. The scale is calibrated in half degree increments, labeled every ten degrees.
Stage rotation is controlled by angled rack(blue arrow) and angled pinion controlled by knurled knob(red arrow). The stage can also be rotated manually; the machining is so exact that this is smooth despite the fact the pinion is still engaged. Also seen in the image to the left is the rack and pinion controlling the stage movement in the forward and backward direction ('Y-axis'). The pinion (green arrow) is long, so as to allow right-left movement while maintaining contact throughout the right-left travel. Right-left movement ('X-axis') is controlled by wormscrew (yellow arrow). The concentric controls for these movements are the invention of Turrell.
The slide-holding mechanism has 2 sliding plates on top. The most proximal one can be affixed in two different positions with the small screw knob, and has an L-shaped stop on a separate plate to register the slide on the left side of the stage. The more distal plate slides freely, and has two buffered spring clips, which maintain pressure against the slide. As you can see, the 2 screw hole positions allow for correct positioning of a standard 1 x 3 inch and an oversize slide, and the freely moving distal plate allows one to use a slide of any size.
Located at the left rear corner of the stage are calibrated scales, one provided for the 'X' movement and one provided for the 'Y' movement of the stage.
