732 PROCEEDINGS OF THE SOCIETY. 



he was in doubt whether the antipoint was entirely produced in the 

 instrument, or partly in the eye. He thought Mr. Gordon's suggested 

 investigations into the part the eye might play were important. 



Mr. C. Beck thought that in the case of the instruments on the 

 table tie antipoint was certainly produced by the instrument, and that 

 it was only when a very high ocular was used that it was produced by 

 the eye. 



Dr. G. P. Girdwood's paper ' On Stereomicrography ' was read by 

 Dr. Hebb, and was illustrated by a drawing on the board and by a 

 specimen in a stereoscope handed round for inspection. 



The President thought that the method described was ingenious, and 

 the result successful. A vote of thanks was unanimously passed to 

 Dr. Gird wood for his paper. 



New Fellows :— Messrs. M. Anslow Alabone, J. W. Gordon, S. A. S. 

 Metheny, and Joges. C. Eay were elected Ordinary Fellows of the 

 Society. 



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



Mr. Conrad Beck :— Exhibition of Antipoints. (1) A fine point of 

 light viewed with a ^-in. objective of ordinary aperture, showing point 

 surrounded with faint diffraction circles. (2) A fine point of light 

 viewed with a i-in. objective of very small aperture, showing disc of 

 light and diffraction rings. (3) A fine point of light viewed with a 

 i-in. objective with fine slit placed behind it, showing slit-shaped 

 image with rows of slit-shaped images right and left. (4) A fine 

 point of light viewed through a ^-in. objective with a small triangular 

 aperture placed behind it, showing small disc image with six radiating 

 arms of diffraction images arranged like a star. (5) A fine point of 

 light viewed through a =L-in. objective with a diaphragm having three 

 circular apertures arranged in the form of a triangle placed behind 

 the objective, showing central disc surrounded by six small discs and 

 again surrounded by twelve fainter small discs. (6) A fine point of 

 light viewed through a grating which extended for the whole aperture 

 of the t^-in. objective, showing a punctiform central image and slit- 

 shaped diffraction images on either side. 



Messrs. B. and J. Beck (Ltd.) : — Two Microscopes fitted with Ashe's 

 new Fine Adjustment. 



Mr. C. Lees Curties : — An old Microscope by John Cuff. 



Bev. Canon Carr, Messrs. J. W. Gifford, Sidney T. Klein, A. D. 

 Michael, E. M. Nelson : — A Microscope by Powell and Lealand, 

 dated 1848. 



Prot. G. P. Girdwood :— A Stereoscopic Photomicrograph in illus- 

 tration of his paper. 



The Bight Hon. Sir Ford North :— A Microscope made by Plossl et 

 Cie., Wien. 



Messrs. Wm. Watson and Sons :— An old Microscope by Hugh 

 Powell. 



