620 PROCEEDINGS OF THE SOCIETY. 



A comparison of the centimetre of the plate marked No. 1 with 

 the centimetre of the plate marked A, gives the following results : — 



At 62° Fahr. 

 1883. May 23. No. 1. -04/^ = A. 

 May 24. No. 1. •29/.i = A. 

 May 25. No. 1. •09/>t = A. 



When the definitive value of A is determined the relations given 

 above will be sufficient for the exact determination of the error of 

 the centimetre of plate No. 1. The amount of this correction will, 

 however, be found to be so small that it will be of no practical 

 imjDortance. 



It is proper to add that the glass plate was ruled nearly two 

 years in advance of the preparation of the platinum-iridium plate." 



Mr. H. G. Madan's note on a modification of Barker's Selenite- 

 holder was read. 



Dr. Hudson's letter was read, identifying the orange-coloured 

 rotifers found by the Eev. E. J. HoUoway {ante, p. 474) as Philodina 

 roseola. 



The following Instruments, Objects, &c., were exhibited: — 



Mr. Coppock : — Eozoon canadense from Sutherlandshire. 

 Mr. Crisp : — (1) Bailey's Portable Microscope. (2) Swift's new 

 form of Wale's Working Microscope. 



Mr. Hitchcock : — American Fresh-water Sponges. 



Dr. F. C. Kiaer : — Photomicrographs taken by lamplight. 



Mr. J. Mayall, jun. : — Dr. Schroder's Polarizing Apparatus. 



New Fellows ; — The following were elected Ordinary Fellows : — 

 Messrs. H. F. Atwood, H. P. Aylward, Frank E. Cheshire, Eev. 

 W. E. Codling, Ezra H. Griffith, George Hunt, F.E.A.S., Wm. J. 

 Lewis, M.D., John M. Offord, Eobert Peach, and B. W. Thomas. 



Walter W. Eeeves, 



Assist, -Secretary. 



