2 1);". 



PEOCEEDINGS OF THE SOCIETY. 



MEETING 



Held on the 19th of February, 1908, at 20 Hanover Square, W. 

 A. N. Disney, Esq., M.A., B.Sc, in the Chair. 



The Minutes of the Meeting of the 15th of January, 1908— being the 

 Anniversary Meeting of the Society — were read and confirmed, and were 

 signed by the Chairman. 



The List of Donations to the Society (exclusive of exchanges and 

 reprints) received since the last Meeting, was read, and the thanks of the 

 Society were voted to the donors. 



From 

 J. M. Hulth, Bibliographia Linnaeana. Partie I., Livraison 1.1 Kungl. Vetenskaps 



(8vo, Upsala, 1907) J Societeten i Upsala 



Conrad Beck, Cantor Lectures on The Theory of the Micro- 1 



scope. Delivered at the Society of Arts, Nov. and Dec. > The Author. 



1907. (8vo, London, 1908) ) 



Slide, A Iveolina boscii .. .. Mr. F. Chapman. 



Mr. J. E. Barnard exhibited and described an improved type of 

 mercury vapour lamp. The lamp exhibited on a former occasion had 

 been improved on, and the one now shown was made with a thicker and 

 shorter tube. This gave a sufficiently large source of light to enable 

 critical illumination to be obtained with a well filled field, when using 

 medium powers. The effect of using this new form of lamp was 

 shown under two Microscopes in the room, one with a screen, giving 

 absolutely monochromatic green light, the other without a screen, the 

 soft blueish light in which was very pleasant to work with, and, owing 

 to the entire absence of red rays, constituted an excellent illuminant 

 for visual microscopic work. 



Mr. J. W. Gordon inquired if Mr. Barnard had satisfied himself as 

 to the absence of any short-length waves of light, which might prove 

 injurious to the user. The danger which lurked in that sort of thing 

 had been brought home to them lately by the fact that Dr. Hall 

 Edwards had lost his arm through incautious operating with X-rays, 

 at a time when the risks of damage from that source were unknown and 

 unsuspected. 



Mr. Barnard said this risk was really nil, owing to the incan- 

 descent mercury vapour being inclosed in a glass tube, which of course 

 absorbed practically all the ultra-violet rays. A further safeguard in 



April loth, 1908 I 



