Zentmayer § Portable Microscope . By E. M. Nelson. 27 
is peculiar: it, in common with those of most portable Microscopes, 
revolves on a pivot, but in this one the pivot is not in a line with the 
axis, but is a little towards the right-hand side of the sta^e ; and 
curiously the hole in the stage is not in its centre, but is displaced 
1/8 in. nearer to the right-hand side. When the stage is rotated into 
position it is held there by a spring notch. 
To pack up the instrument the legs are bent back against the 
limb ; the stage, being released from the spfing notch, is turned through 
3/4 of a whole revolution, until it lies along the body as in fig. 5. 
The mirror, by means of its cranked arm, is turned against the other 
side of the body ; the sliding arm however packs separately in the lid 
of the box. 
Fig. 5. 
There .is a new feature about the box, it has a stout brass plate 
attached to the bottom to impart steadiness. The weight of the box 
is 13 oz., and that of the Microscope with an objective is 17 oz. My 
Jubilee Microscope,* with objective and substage condenser, weighs 
14 oz., and its stand 2 lb. ; its foot might screw into the lid of its 
box, and thus the stand might be dispensed with. The Zentmayer 
has the more rigid limb and legs, while mine has the more rigid stage. 
The size of the Zentmayer when closed, and without its box, is 
4J x 2J x If in., while that of the Jubilee is 4J x 3 x 2 in. ; its body, 
which is 4 in. long, is separate. The distance of the optic axis from 
the limb in the Jubilee is 1^ in. as against 3/4 in the Zentmayer. This 
is a defect in the Zentmayer, for when the sliding bar is on the stage 
nothing can be seen on a 3 x 1 slip higher than 1/8 in. from the 
centre. If an object were higher than this the slide would have to 
be reversed. This might not make much difference beyond a slight 
inconvenience with mounted objects, but it w T ould be very inccm- 
venient whilst following living objects. If the sliding bar were re- 
placed by the original spring clips, a little more but still an insufficient 
amount of play would be given to the slide. 
* See this Journal, 1887, p. 1013, figs. 238, 239. 
