ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 103 



mechanical stage of the Turrel pattern. The pillar of the Microscope also 

 carries a jointed arm, which can be fixed at any height, with holder for 

 a candle and stage-condenser. There are fonr oltjectives — single, non- 

 achromatic bi-convex lenses. The name " Engiscope " was given Ijy 

 C. R. Goring to designate a " Compound ^licroscoxje," his intention 

 being to retain the expressions " Microscope " or " Simple Microscope," 

 to denominate what was then called a " Single Microscope." The sug- 

 gestion was, however, not adopted, and the name was soon dropped. 



This interesting old Microscope has been presented to the Society by 

 A. F. (t. Warrington, who discovered it in India, where it had evidently 

 been for a great many years. 



Crouch's "D.P.H." Microscope.* — This Microscope (fig. 8) has 

 been constructed for research and other work of the highest class in 

 Bacteriology. The coarse focusing adjustment is by diagonal rack-and- 

 pinion, the bearings of which are much wider than ordinarily made and 

 consequently much more solid and durable. The fine-adjustment is 

 executed by the direct action of a left-handed micrometer screw, oper- 

 ated by a triangular bar and working on a polished hardened steel 

 plate. The large stage has rectangular adjustments by means of a diagonal 

 rack-and-pinion and quick screw, with a range in each direction of 25 mm., 

 each adjustment having a graduated millimetre scale. The substage has 

 a swing-out movement and is focused by means of a diagonal rack-and- 

 pinion ; but, by special request of several eminent bacteriologists, cen- 

 tring adjustments are not included. 



This model is also made with a specially constructed stage and a 

 larger body tube. It is then listed as the " Army Medical." 



It can also be supplied with a horse-shoe foot. This adds 3 lb. to its 

 weight. C' Tropical " Model.) 



(3) Illuininatiiig- and otlier Apparatus. 



Ultra-violet Monochrometer.l — C. Leiss describes the above appar- 

 atus, which has been made by the firm of Fuess to his designs. Its 

 object is to obtain readily ultra-violet light of any required wave-length. 

 The apparatus is shown in figs. 9 and 10. The dispersion system is 

 a quartz double prism with constant deviation of 90% as proposed by 

 Straubei. The advantages of such a prism are that it is practically free 

 from double refraction, and that every part of the light incident in the 

 field of view of the fluorescing ocular is in the position of minimum 

 deviation. Rotation of the system is attained by a screw, whose division 

 drum is graduated according to wave-lengths corresponding to a range 

 between 500 /x/x and 200 /x/x. 



In the figures, E is the entrance slit and A the exit sUt ; both are 

 symmetrical." A tube L is connected with A and carries an adjustable 

 projection lens O3 which, as desired, either parallelizes the light or throws 

 an image of the exit slit at double the focal distance on any required 



* Catalogue, Crouch's Microscopes and Accessories, S. Maw, Son & Sons, 

 London. 



t Zeitschr. f. Instrumentenk., xxxii. (1912) pp. 292-4 (2 figs.). 



