724 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Grunow's (J.) Camera Lucida. [_Supnt, p. 713.] 



Amer. Mon. Micr. Juurn., IV. (1883) p. 138. 

 Haeeis, W. H., aurl H. Crowthee.— Sujrgestions for an Exchauge Club. 



[" Sometliing after the style of tlie Postal Microscopical Society, but with 

 less routiue, which might be put briefly thus : — No fees, uo secretary, uo 

 journal, no annual meeting."] 



Sd.-Gosslp, 1883, pp. 209-10. 

 Hitchcock, K.— Instructions in Dry-plate Photography. {Concluded.) 



Amer. Mon. Micr. Journ., IV. (1883) pp. 124-6. 

 „ „ Notes from abroad. 



[Describes a visit to E. M. Nelson's studio and his methods of illumination 

 — Fisheries Exhibition — Fresh-water medusa at the Quekett Club — 

 Moller's 1600 type -slide — Watson's new Microscope— Photomicrographs.] 

 Amer. Mon. Micr. Journ., IV. (1883) pp. 129-32. 

 „ „ The Aperture Shutter. 



[" An examination of the subject with Mr. Davis to make the demonstra- 

 tion has fully satisfied us that the aperture shutter does greatly increase 

 the penetration of a low-power objective. We mean by this an objective 

 of not more than 1-2 in. focal length."] 



Amer. Mon. Micr. Journ., IV. (1883) pp. 13i-5. 



,, „ The American Society of Microscopists. [Reminder of the 



Chicago Meeting.] Amer. Mon. Micr. Journ., IV. (1883) pp. 135 and 140. 



„ „ Oculars. 



[Many oculars show objects greatly distorted. " This is mainly owing to 



the fact that makers have departed from the proper formula for placing 



the lenses in relation to their respective focal lengths."] 



Amer. Mon. Micr. Journ., IV. (1883) p. 136. 

 „ „ A " Scientific Evening." 



[Describes the Scientific Evening of the Eoyal Microscopical Society on 

 2nd May.] 



Amer. Mon. Micr. Journ., IV. (1883) pp. 136-7. 

 „ „ Eesolution of AmpMpleura pellu^ida by central light. — Oblique 



light for resolution. 



[" Mr. E. M. Nelson . . . states that any of the homogeneous-immersion 

 objectives in use will resolve the lines with central artificial light. . . . 

 Nevertheless, the ease and distinctness with which the resolution was 

 made by Prof. Forbes (by sunlight) is surprising." — "Mr. Nelson does not 

 approve of oblique light for resolution. He prefers to use central light in 

 the study of markings on diatoms because oblique light often shows 

 lines when central light shows dots — hence oblique light is misleading. 

 One need not look far to discover a fallacy in the argument thus sug- 

 gested."] 



Amer. Mon. Micr. Journ., IV. (1883) pp. 137-8. 



„ „ Mr. W. Teasdale's Spot-lens. 



[" A good-sized glass fish-eye . . . mounted in a piece of cork makes a very 

 satisfactory spot-lens indeed."] 



Amer. Mon. Micr. Journ., IV. (1883) p. 138. 

 „ „ Zeiss's Catalogue. 



[" Zeiss now makes a corrective-adjustment for his homogeneous-immersion 

 lenses, but tlie object of the adjustment is to correct for the varying length 

 of tube and not for difierent thicknesses of cover-glasses."] 



Amer. Mon. Micr. Journ., IV. (1883) pp. 138 and 139. 

 „ „ Homogeneous-immersion Objectives. 



[Satirical account of their condemnation by an English microscopist.] 



Amvr. Mon. Micr. Journ., IV. (1883) p. 139. 

 „ „ " New Wenham Binocular Prism." 



[" Boss and Co. have at last succeeded in reducing the cost ... so that 

 they are able to introduce it."] 



Amer. Mon. Micr. Journ., IV. (1883) p. 139. 



