STAGE AND OBJECT HOLDER. 27 



In figs. 2 and 3 is shown an arrangement by which this result is 

 automatically secured for objects of inappreciable thickness, fig. 3 

 being a transverse section of fig. 2. The carrier-plate D D is 

 provided with brass forks N N, and a narrow transverse opening, 

 P P, through which springs R R press the object-slide against the 

 lower surfaces of the forks N N. As these surfaces are in line with 

 the centre M of the hemisphere, minute objects can readily be placed 

 in that centre. It will be seen that this arrangement automatically 

 compensates for the varying thickness of slides ; and that of objects 

 may be compensated for by the screws W W — two of the screws 

 being tapped into one of the forks, N, and one into the other fork. 



Fig. 1 represents the most convenient form for use with reflected 

 light. For the employment of transmitted light, either with the 

 microscope or with Hoflmann's Table Polariscope, the arrangement 

 shown in fig. 2 is provided with an aperture X X in the carrier- 

 plate J), and similar apertures, Y in the spherical segment E and Z 

 in the base-plate A. The weight of the upper part of this arrange- 

 ment will be found sufficient to retain it in any position, especially 

 if the upper edge of the tube C be finished square or bevelled out- 

 wards, so as to give a better bite on E. Either form permits free 

 tilting and rotating movements in all directions, within certain 

 defined limits. 



Fig. 4 represents in vertical section an adaptation of the same 

 IDrinciple for disc-mounted objects. In this case E E is a hemisphere, 

 along the inner edge of which is soldered a brass ring, V V. The 

 upper surface of this ring is flush with the centre M of the sphere. 

 Inside the hemisphere E, and at its lower part, is soldered a short 

 tube S, in which slides telescopically the carrier T, provided with a 

 socket to receive the disc U. Any object affixed to the disc U can 

 thus be readily adjusted, flush with the upper surface of the ring Y, 

 and can receive motion in every direction, without eitlier lateral or 

 vertical displacement. The hemisphere E will stand secure in any 

 position, and every point of a hemisi^herical object may be examined. 



In each form of this apparatus the point M must be kept in the 

 axis of the microscope. The carrier-plate D should therefore be 

 large enough to pemiit of any necessary movement of the slide upon 

 it ; and, for use with non-mechanical stages, a tubular projection 

 from the lower surface of the base-plate A, to fit the " well " of the 

 stage would be advantageous. 



The arrangement shown in fig. 4 could obviously be made to 

 carry a slide or a disc-mounted object at pleasure. 



