PROCEEDINGS OF THE SOCIETY. 
907 
exposure of twenty minutes he got just the ghost of an image, whereas 
with the light of an ordinary paraffin lamp he obtained a beautifully 
developed picture in a very much shorter time. If Dr. Piffard had sent 
any specimens taken in the way described in his paper, he should very 
much like to see them. 
Prof. Bell said that no specimens had been received. 
Mr. C. Haughton Gill said that he had used the copper light-filter 
for the same purpose, and had found that by its aid any good ordinary 
lens would give as good results as you otherwise would get by using an 
expensive apochromatic, because it filtered off all the rays except those 
which were visually strong. His experience was that no advantage 
was to be obtained by expensive lenses over others when this method 
was adopted, for with this lightffilter he could get just as good a picture 
with an objective such as cost about 30s. as he could with one costing 10Z. 
He had not found in the course of his own work that the use of this 
light prolonged the exposure, that was to say, that with a magnifying 
power of X 300 and an exposure of ten minutes he could with the 
isochromatic plates get a good strong printing image. 
The Chairman said that in the absence of Mr. Massee they had come 
to the end of their Agenda; it only remained for him to remind them 
of the Conversazione on November 30th, and to adjourn the meeting to 
November 16th. 
The following Instruments and Objects were exhibited: — 
Dr. C. E. Beevor: Photomicrographs and sections illustrating his 
paper. 
Mr. H. G. A. Wright: Photomicrographs of Podura scale and of the 
Blow-fly’s tongue. 
Messrs. J. Swift : — Aluminium Microscope. 
New Fellows: — The following were elected Ordinary Fellows: — 
Messrs. Charles Edmund Aikin, Frank Campion, and Camille Charles 
Muiron. 
Meeting of 16th November, 1892, at 20, Hanover Square, W., 
The President (Dr. K. Braithwaite, F.L.S.) in the Chair. 
The Minutes of the meeting of 19th October last were read and 
confirmed, and were signed by the President. 
The List of Donations (exclusive of exchanges and reprints) received 
since the last meeting was submitted, and the thanks of the Society given 
to the donors. 
From 
Monograph of the Palaeontographical Society, 1891 Mr. F. Crisp » 
A Guide to the Science of Photomicrography. By E. C. Bousfield. 
(8vo, London, 1892) The Author , 
A Contribution to our Knowledge of Seedlings. By the Right Hon. 
Sir John Lubbock, F.R.S. 2 vols. (8vo, London, 1892) . . .. „ 
3 p 2 
