A STAGE ATTACHMENT FOR THE METALLO GRAPHIC 



MICROSCOPE 



ALBERT D. BROKAW 

 University of Chicago 



A device to obviate the necessity of mounting specimens that 

 have been polished on one side only has been found very convenient 

 by the writer. It consists of a disk of brass with a hole about three- 

 eighths of an inch in diameter at the center. The lower surface 

 is plane and the upper side is turned to an inverted conical surface, 

 shown in plan and elevation at D in Fig. i. The disk is fitted into 



the stage aperture, where it may 

 be held by a steep pitch screw, in 

 which case the outer edge of the 

 lower projection is milled. The 

 post P is screwed into the stage 

 from below, at one corner. A 

 spring S is attached to a brass 

 block, held in place by a set screw. 

 This spring supports the specimen, 

 which is placed with its polished 

 surface against the lower side of 

 the disk. The spring pressure is 

 controlled by the position of the block. The upper side of 

 the disk is cut away to allow the objective to come to its focal 

 distance from the surface to be ex- 

 amined. The plane surface of the 

 disk is perpendicular to the axis 

 of the microscope; consequently 

 the whole field is brought into 

 focus at the same position, without the usual care necessary in 

 mounting the specimen. The specimen may be moved around 

 without loosening of the spring, except in the case of unusually 

 irregular pieces. 



718 



Fig. 1. — Plan and elevation of 

 attachment. 



Fig. 2. — Spring clip. 



