ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



859 



Fig. 160. 



If the thread of the nose-piece of the Microscope is filed down in 

 the same way as in the adapter N, the latter may be dispensed with, 

 and it is, as we have said, a special feature of Mr. Nelson's suggestion 

 that the alteration to the objective thread in no way hinders its use 

 with the ordinary nose-piece, and unaltered objectives will in the same 

 way fit nose-pieces which have been filed down. 



Gundlach's Calotte Diaphragm. — Mr. Gundlach has devised the 

 very neat form of calotte diaphragm shown in Fig. 160, for application 

 to his " College " Microscope 

 (ante, p. 670). 



The calotte C is pierced 

 with five apertures, varying in 

 size from a pin-hole to -| inch, 

 and is attached to a hollow 

 metal hemisphere H, by a screw 

 at a point 45° from the vertex, 

 which allows it to rotate so 

 that the apertures pass succes- 

 sively over an opening at the 

 top of the hemisphere. H itself 

 is fixed to a spherical segment 

 of metal, and the latter to a 



short piece of cylindrical tube so as to slide into the substage B, ; 

 an outer shell S, of ebonite, rotates round H, and the edge of the 

 calotte C being milled and in close contact with S, the rotation of 

 the latter causes the calotte to revolve also. A projecting pin on the 

 tube fits into a slot in the substage ring to prevent H from rotating. 



More space for the hand between the stage and the outer edge of 

 the ebonite shell would be obtained by adopting a conical instead of 

 a spherical form of shell. 



Bohm's Wool -measurer.* — This (Fig. 161) _ is intended for 



Fig. 161. 



examining the wool of sheep under the Microscope, but it can also be 

 used for the anthropological comparison of human hair, as well as for 



* Bericht u. d. wiss. Instrumente a. d. Berliner Gewerbeausstelluug im 

 Jahre 1879 (Loewenherz, 1880) pp. 313-4 (1 fig.). 



