﻿Vol. 6 1.] PROCEEDINGS OP THE GEOLOGICAL SOCIETY. vii 



February 1st, 1905. 

 J". E. Mark, Sc.D., F.R.S., President, in the Chair. 



Charles Griffith, M.A., Barnes Close, "Winchester ; V.S. Sambasiva 

 Iyer, B.Sc, L.C.E., Curator in the Mysore Geological Depart- 

 ment and Lecturer in Geology at the Central College, Bangalore 

 (India); George Maxwell Lawford, M.Inst.C.E., 9 Bridge Street, 

 Westminster, S. W.; Walter Reginald Gibson Rivington, Assoo.Il.S.M., 

 Assoc.I.M.M., Norman hurst, Northwood (Middlesex) ; Eranz Eduard 

 Studt, 13 Moscow Road, Stockport ; Carl Adolph Siissmilch, Lecturer 

 in Geology, Mineralogy, and Mining at the Sydney Technical College, 

 Sydney (N.S.W.) ; and Isidore Tom, Assoc.R.S.M., Pyrenees 

 Minerals Ltd., Alzen Mines, La Bastide de Serou, Ariege (France), 

 were elected Fellows of the Society. 



The List of Donations to the Library was read. 



Prof. Garwood exhibited and commented on a set of* twelve 

 lantern-slides, illustrating the use of three-colour 

 photography in demonstrating the microscopic 

 characters of rock-forming minerals in polarized 

 light. 



Mr. A. P. Young said that he would like to learn what were now 

 held to be the three primary colours, the practice in this respect 

 appearing to have undergone some changes since the early days of 

 colour-photography. 



Prof. Watts pointed out the immense value of the photographs 

 exhibited for teaching purposes. The colours were wonderfully 

 accurate and beautiful; and, besides this, the refractive index was 

 well-shown. He hoped that copies of these photographs might, 

 some day, be available for teachers. 



Prof. Garwood replied to Mr. Young that the slides were taken 

 by the Sanger- Shepherd process, in which yellow, green, and red 

 screens were used. In answer to a question from Dr. Teall, he said 

 that it was not a process that could be used very easily, but one 

 which required a good deal of time to produce really-accurate prints. 

 Considerable difficulty was experienced in procuring objectives which 

 were truly corrected for the spectrum, the tendency in the case of 

 interference-figures being to give different-sized rings for different 

 colours. He agreed with those who had taken part in the discussion, 

 that the results did resemble very closely the phenomena seen under 

 the microscope ; and he had brought one or two rock-sections, shown 

 on the screen, in case Fellows interested in the subject would like 

 to compare the slides with the original sections. 



The following communication was read: — 



' On the Sporangium-like Organs of Qlossopteris Browniana, 

 Brongn.' By E. A. Newell Arber, M.A., F.L.S., F.G.S. 



