ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



121 



correcting to infinity a myopic eye. The stronger the myopia, the 

 weaker may be the lenses used to produce a considerable magnification. 

 Thus for a myopic eye of — 8 D, to produce a magnification of ten times, 

 the object-lens need only be one of -f- 13*5 D, and the drawing lens 

 one of — 9 D. To bring any eye then to this state of myopia, a suitable 

 convex lens is placed in (he eye-piece. By this means high magnification 

 up to ten times can be obtained without distortion of the images. 



Finder.* — Dr. J. Pantocsek describes the finder shown in fig. 12, 

 which he considers to be more serviceable than Maltwood's finder, which 

 he considers " time-wasting " and " minute." 



Four lines are drawn on the stage at right angles, intersecting in 

 the optic axis ; these are marked 0. Lines a millimetre apart are 

 drawn parallel to those on the upper half and the left half of the 

 finder, thus giving horizontal lines in the right upper quadrant, vertical 



Fio. 12. 



lines in the left lower quadrant, and squares in the left upper one. 

 Each ten of the lines are marked as shown in the fig. When the 

 object is in the field, note is taken of the two lines on which the left and 

 upper sides of the slide rest, thus : 42/11. 



Ficx. 13. 



Adjustable Safety-stage.— In this form of safety-stage the additional 

 refinement has been introduced of two clamp screws at either end of the 



* Zeitschr. f. Wiss. Mikr., v. (1888) pp. 39-42 (3 figs.). 



