108 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



to discontinue it. The rackwork in the 

 a number of grooves cut on a cylinder, 



that they have determined 

 above auxiliary consists of 



against which a pinion engages, as in the ordinary coarse adjustment of 

 Microscopes. This can be mounted strongly, and to work accurately 

 on almost any Microscope. It is provided with a loose ring, by which 

 it is centred precisely to the Microscope, with which it is to be used, 

 before leaving Messrs. Watson's works, and the ring is then held by 

 screws in position. 



Watson's Compound Substage.* — This substage (fig. 8) has spiral 

 rackwork, pinion, coarse adjustment, and centring screws, to enable the 

 apparatus that may be contained on it to be set exactly coincident with 

 the optical axis of the objective. 



Fig. 8. 



Metallurgical Stage.f — W. B. Stokes has devised an appliance, 

 intended to effect a temporary conversion of any Microscope possessing 

 a focussing substage into a stand suited to the needs of metallurgists. 

 When using the " vertical illuminator," a change of object often in- 

 volves a considerable change in the illumination, but by giving the 

 stage a focussing movement the lighting arrangements remain undis- 

 turbed. The aim of the present accessory is to supply this movement 

 to an ordinary Microscope. Taking advantage of the substage move- 

 ment, it is evident that there is required only a stage-plate fixed to a 

 stem, which fits into a substage adapter in such a way that the stem 

 passes through the ordinary stage aperture. 



Pocket-Magnifier.f — G. C. Karop describes a new pocket-lens 

 (fig. 9) made by Swift and Son. It is a modified Herschelian doublet, 

 made up of a lower inequi-convex 6 : 1 lens, and an upper plano- 

 convex of smaller size, just sufficiently spaced to admit a thin polished 



* W. Watson & Sons' Supplemental List, October 1903, p. 7. 

 t Journ. Quekett Micr. Club, viii. (1903) pp. 549-50 (1 fig.). 

 X Tom. cit. pp. 499-504 (8 tigs.). 



