332 RECORD OF CURRENT RESEARCHES RELATING TO 



its extent. The dot M indicates tlie centre of the sphere, and should 

 be fully x(7 of an inch above the upper surface of the plate D. 



Fig. 21. 





The carrier plate 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 hemisjihere, minute objects 

 mounted on an ordinary glass slide can readily be placed in that 

 centre, and will be practically free from displacement, lateral or 

 vertical, in any position of the carrier plate. 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 may be tapped into one of the forks N, and one 

 into the other fork. 



Fig. 22. 



' ^^ 



by/'f/M'/z/mw/A 



The weight of the upper part of this arrangement is sufficient to 

 retain it in any position, especially if the upper edge of the tube C 

 be finished square or bevelled outwards so as to give a better bite 

 onE. 



Mr. West describes another form, available only for opaque objects, 

 in which E E is secured to C C by springs, and also a modified form for 

 disk-mounted objects. 



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

 axis of the Microscope. The carrier plate D should therefore be 

 large enough to permit 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. 



Modification of Stephenson's Safety Stage. — At the March meeting 

 of the Society, Mr. Washington Teasdale exhibited a modification of 

 this stage made of ebonite, which was generally commended for its 

 lightness, the material also allowing of a considerable reduction in 

 the cost. An arrangement is provided for introducing and revolving 

 selenites, diaphragms, light modifiers, &c., beneath the object. 



