FAMILY MICROSCOPE. 57 



sized English accessories; revolving diaphragms, etc. 

 These are all attached to the swinging mirror bar, the 

 axis of which is placed at the level of the object, so that 

 the diaphragm and mirror swing concentrically around 

 the object. The mirror can also be moved on the mir- 

 ror bar to and from the object, and the distance between 

 the latter and the sub-stage can be varied by reversing 

 it. Both sub-stage and mirror can also be removed. 



It is to be observed that in these two instruments the 

 importance of the swinging bar, before described in 

 connection with the Centennial and Histological stands 

 of Mr. Zentmayer, has been recognized by Mr. Gund- 

 lach. The mechanism, however, by which these makers 

 accomplish the swing in the plane ot the object, is by 

 no means the same in their respective stands. Thus the 

 peculiar method of securing the stage to the limb, em- 

 ployed by Mr. Zentmayer, allows that the sub-stage 

 with its accessories, and the mirror, be brought entirely 

 above the stage, the only thing preventing a, full revo- 

 lution being the body tube, while in the instruments of 

 Mr. Gundlach the swinging-bar plays in a slot cut in 

 the rear of the main stage plate, and the swinging 

 motion is thus circumscribed by the stage slot. 



FAMILY MICROSCOPE. 



This has japanned cast-iron foot and pillars support- 

 ing the axis which carries the body, so that it may be 

 inclined to any angle revolving diaphragm below the 

 stage; rack and pinion for adjustment of focus; con- 



