714 PEOCEEDINGS OF THE SOCIETY. 



He had, however, telegraphed from Deal that he was unable to reach 

 Loudon in time for the meeting, and his remarks must therefore be 

 taken as read (see p. 668). 



Mr. Stephenson, in reply to the Chairman, said he concurred with 

 Mr. Crouch in regarding swinging substages as useless incumbrances. 

 The large apertures of the modern immersion objectives could only 

 be utilized by immersion condensers, and for such condensers a 

 swinging substage was unsuitable (see p. 669). 



Dr. B. Wills Richardson's paper, " On a Blue and Scarlet Double 

 Stain, suitable for Nerve and many other Animal Tissues," was read 

 (see p. 573). 



Mr. Crisp exhibited and explained the construction of " Gund- 

 lach's Periscopic Eye-pieces " (see p. 659), and briefly epitomized the 

 pajier of Mr. J. D. Cox on the motion of diatoms (see p. 649). 



Dr. Savage's note was read, asking for the experiences of the 

 Fellows as to the changes which took place in spirit-hardened tissues, 

 especially in the case of nervous tissues (see p. 695). 



Mr. Crisp referred to the insufficiency of the views put forward 

 by Mr. J. B. Haycraft (Proc. E. Soc, xxxi. (1881) pp. 360-79) on 

 the cause of the striation of voluntary muscular tissue. 



Mr. E. M. Holmes read a paper " On a new British Alga," speci- 

 mens of which were exhibited. 



Mr. Crisp said that Mr. T. Powell would at the close of the 

 meeting demonstrate, by means of Woodward's and Abbe's aper- 

 tometers, the very large numerical aperture of his new oil-immersion 

 objective = 1 • 47 N. A., the largest hitherto made. 



Mr. Stephenson exhibited an |^ and a 1-inch objective made in 

 the year 1835 by the late Andrew Boss for the Society of Arts, 

 and presumably of the then highest standard of excellence, as they 

 were made for presentation by the Society to Mr. Aikin, in recog- 

 nition of services rendered by him in that year. Mr. Stephenson 

 pointed out that the great interest was in the advance which had 

 been made in the construction of objectives during the last forty-six 

 years, as indicated in the ^ of 1835 by Ross and the homogeneous ^ 

 of 1881 by Powell and Lealand, both of which were on the table that 

 evening. Boss's ^ of 1835 with its triple front had a numerical 

 aperture of • 29 only, whilst the homogeneous 1 of Powell and Lealand 

 had the immense aperture of 1 • 47 — showing an increase in resolving 

 power, as well as in light, of no less than 500 per cent. The 1 inch 

 of Ross of the same date (1835) had a numerical aperture of 0" 10 as 

 contrasted with the not unusual aperture of 0*25 of the present day. 



