ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



255 



that furnished by some of the modern binoculars would be likely 

 to be more than balanced by the additional complication of the 

 instrument. 



Nachet's Double-bodied Microscope-tube.* — An ordinary Micro- 

 scope can be readily converted into one for two observers by the plan 

 shown in Figs. 34 and 35. A nose-piece screws into the end of the 



Fig. 35. 



body-tube, carrying just above the objective a truncated prism, 

 which bisects the pencil from the objective, allowing half to pass 

 direct to the eye-piece, while the other is diverted by the prism into 

 a second tube screwing into the nose-piece and set obliquely. Powers 

 of 200 to 300 times can be used. 



Wenham's Universal Inclining and Rotating Microscope. — This 

 new Microscope (Plate IV.) has been devised by Mr. Wenham for 

 the special purpose of obtaining a large range of effects of oblique 

 light both in altitude and azimuth. 



The principal movements are as follows : (1) an inclination of 

 the limb together with the body-tube, stage, substage, and mirror, 

 in a sector sliding within jaws attached to the rotating base-plate. 

 The centre of this inclining motion is (very approximately) the 

 point where the plane of the object cuts the optic axis, i. e. a point 

 situated about the thickness of an ordinary object-slide above the 

 centre of the surface of the stage ; (2) a lateral inclination of the 

 limb to either side upon an axis attached to the centre of the sector. 

 The centre line of this axis prolonged forwards also intersects the 

 optic axis in the plane of the object on the stage ; (8) a rotation of 



* See Robin, C, ' Traite du Microscope,' &c., 1877, pp. 72-3 (2 figs 



