PROCEEDINGS OF THE SOCIETY. 1073 



appliances he had been able to see a faint white stripe on either side of 

 Henscn's dark stripe. The sequence of the eight stripes is as follows : — 

 A white stripe. Huxley and Busk's dark. White. Dark. Nelson's 

 light. Hcusen's dark. Nelson's light. Dark. He estimated the diameter 

 of these stripes to be all equal. In a muscular fibril of a pig he found its 

 diameter to be 1/11,500 in., and the length of the pattern 1/11,000 in. 

 Therefore the diameter of the stripes may be estimated as about 1/88,000 in. 

 Although he saw evidences of longitudinal breaking up, he could see nothing 

 of Schafer's beads. There were beads visible such as had been described 

 by some observers, but he considered that these were the result of bad 

 resolution causing the breaking up of the fibres. It was curious to note 

 that with objects of this character some eyes seemed as if they always would 

 see beads. 



The third point noticed by Mr. Nelson was the note which appeared in 

 the ' English Mechanic ' of November 4th on Mr. Francis' method of 

 improving definition of such an object as AmpMpleura pcllucida by using 

 the analyser. He had tested the plan, and found that it did intensify the 

 resolution in a very marked degree. It did not resolve anything which 

 the objective could not resolve otherwise, but it certainly did strongly 

 intensify it (supra, p. 1033). 



Mr. Crisp said that the increased effect might be due, as was frequently 

 the case, to an alteration in the intensity of the light. He should therefore 

 like to see if the same effect could not be produced by altering the light 

 in some other way than by using the analyser. 



Mr. Nelson said he had tried altering the light, but it certainly had not 

 the same effect. 



Mr. Powell said he had also tested the use of the analyser, and found 

 there could be no doubt as to the definition being improved by it ; it was 

 also certain that the same definition could not be obtained by reducing the 

 light in other ways. 



Mr. Nelson said he had tried all the most delicate tests, but he found 

 an advantage was gained only b}' oblique light and in a particular 

 direction. 



Mr. Crisp inquired whether in the rotation of the analyser certain 

 spectra were found to be shut off? 



Mr. Nelson said the analyser was large enough to include the whole of 

 the spectra in every position. He could, however, tell what was the best 

 position by the strength of the green. 



Mr. C. Beck suggested that a tourmaline should be tried, so as to see 

 if the effect was exclusively due to polarization. 



Mr. E. M. Nelson also exhibited and described a new portable Micro- 

 scope made by Messrs. Powell and Lealand from his drawings (supra 

 p. 1013). ' 



Mr. J. Mayall, jun., said he was glad that Mr. Nelson had interested 

 himself in the design of so small an instrument, for a want had often been 

 felt of such a Microscope. Generally speaking, a " miniature " Microscope 

 was a mere toy. But here, he thought, Mr. Nelson had added substantially 

 to the stock of working ajiparatus. The convenience of a good portable 

 Microscope was unquestionable, and would doubtless be largely appreciated 

 by microscopists. The arrangement of the lamp did not strike him 

 favourably. He thought that if the instrument had to be handed round to 

 a class or at a meeting, the lamp would be found inconvenient, if not dan- 

 gerous. If he might make a suggestion for the improvement in the 



