SUMMARY OF CURRENT RESEARCHES RELATING TO 



109 



with the object-plane ; let these be numbered, mentally, 1, 2, 3, 4, from 

 the centre (fig. 28). In the same way let the image be similarly divided 

 into the same number of concentric and equi-distant zones, 1, 2, 3, 4, 

 towards the centre (fig. 29) : then the zones bearing the same number 

 will correspond. If, also, object and image be divided up by radii at 

 equal angular distance, then the object-intersection of a zone of a 

 certain number with a radius of any number will correspond to the 

 image-intersection of zone and radius of similar numbers. If the image 

 be received on a glass plate engraved with such a system of circles and 

 radii, the object can then be reconstructed. The author shows that the 

 scale of magnification is a hyperbola, which can be easily drawn and 

 used as a scale of reference. He recommends that the image be viewed 





Fig. 27. 



Fig. 28. 



Fig. 29. 



through a second cone of the same material of more obtuse vertical 

 angle than the first cone : these two cones are mounted in sliding- 

 tubes so that the distance between them may be varied ; and the whole 

 is applied to a Microscope in place of the usual ocular. The Microscope, 

 having an objective in the usual way, is introduced into the bottom of 

 a camera, and arranged so that the objective image is sharply focussed 

 on a ground glass plate. This image could be photographed. The 

 diastoloscope is then applied. The author hopes to realise magnifica- 

 tions of 5000-6000 diameters. He gives some specimens of his results 

 with diatoms. 



F. R. M. S.— Amphipleura Lindheimeri. 



[The writer states that he has counted 76,000 transverse and 65,000 longitudinal 

 stri?e to the inch upon this diatom in a Watson's styrax slide. 



English Mechanic, Ixxx. (1904) p. 455. 



Hunter, J.—" Cross" formula. Proc. Scot. Micr. Soc, iv. (1903-4) pp. 49-51. 



