438 SUMMARY OF CURKENl? RESEARCHES RELATING TO 



turn, and is clamped after adjustment by means of six screws. On this 

 rod is the guide of the sliding piece C, which carries on its left-hand 

 side the Microscope M, having cross-wires in its eye-piece. The slider 

 and Microscope M are moved by a micrometer screw with drum T, 

 which is divided into 100 parts. The drum is turned by a milled head, 

 into which the ivory handle K is fitted for rapid movement. At n is a 

 scale on C, which serves to read the whole turns of the drum. Under 

 the Microscope is the carrier for the strip of paper. With Knorre's 

 system the declination differences are recorded upon a paper ribbon, 

 siniilar to that of the Morse telegraph, by means of a needle which 

 moves with the micrometer, the zero point being marked by a fixed 

 needle. The carrier consists of a brass plate having a groove which is 

 of exactly the same breadth as the ribbon, and about 1 • 5 mm. deep, this 

 depth corresponding to the thickness of the glass plate e which rests in 

 the groove. This plate carries two brass plates, one of which is visible 

 at /, and each of these has at one end a hole which fits over a pin in the 

 carrier. The glass plate presses the ribbon to the bottom of the groove, 

 so that the distance between it and the Microscope is always the same ; 

 the brass plates carry two knobs by which the glass plate is lifted. 

 The ribbon passes between two rollers, the upper of which W is pressed 

 by two springs against the lower, which is turned by the spindle a and 

 milled head h. S is a mirror attached to a universal joint at the head 

 of the column g, which serves to illuminate the ribbon. L is the reading 

 lens held by the rod d, which can be turned in its socket on D by means 

 of the handle c, and provided with two stops which bring it into position 

 either over the scale n or the drum T. 



Leitz's No. 1 Stand. — This is essentially a reproduction of the Zeiss 

 form. Herr Leitz, however, was one of the first of the Continental 

 makers to supply a rack movement and centering screws to the Abbe 

 condenser. 



Adams's large Projection and Compound Microscope. — Plate IX. 

 shows a Microscope of unusual design, bearing the inscription " Adams, 

 inventor, London," which appears to have been intended to be used (1) 

 as an ordinary compound Microscope, and (2) as a projection Micro- 

 scope. 



The body-tube is about 7 in. diameter and 24 in. in length, and is 

 supported on an arc-piece toothed on the edge, in which engages an 

 endless-screw for inclining the instrument more or less in the vertical 

 plane. The base and pillar are of wood. 



The focal adjustment is efiected by an external screw and rod acting 

 on the stage-support, after the manner of the usual focusing movement 

 applied to reflecting telescopes of the Gregorian or Cassegrainian form. 



For viewing images on a screen the eye-piece was removed and a 

 disc of ground-glass was inserted in a slot in the body-tube, and when 

 more of the object was required to be seen in one view it is presumed 

 that the ground-glass was removed from the slot and the large double- 

 lens, shown on the box, was applied at the eye-piece end and the image 

 projected through it upon a disc of ground-glass fitting on the end of 

 the cylindrical mount of the double-lens. 



Tbe stage figured upon the instrument was for viewing opaque 

 objects; the condenser in front collected the light upon the mirror, 

 which was inclined suitably to reflect the rays upon the object. 



