7875.1 Physics. 403 
February 5th, 1875, Mr. W. Carruthers, F.R.S., was elected President; Mr. 
Etheridge, Professor Rupert Jones, Mr. J. L. Lobley, and Mr. Henry 
Woodward being elected Vice-Presidents. 
Sub-Wealden Exploration.—It is to be regretted that the bore-hole, which 
had been carried to a depth of over rooo feet, has been abandoned, owing to 
obstructions caused by accident to the machinery and loss of the tools. Six 
ineffectual efforts were made to recoverthem. The Diamond Boring Company 
have made a favourable offer to commence again, and Mr. Willett, the 
energetic honorary secretary of the Committee directing the Exploration, has 
guaranteed #600, and appeals for funds to carry on the enterprise. So far as 
the old boring is concerned, the results obtained are of great interest, and ina 
scientific point of view they are by no means unsuccessful ; but the immediate 
object being to prove the depth of the Paleozoic rocks in the Wealden area, it 
is to be hcped that the second boring may obtain the desired information, 
which, while of so much interest to geologists, is most likely to throw some 
light on the vexed question of the probability of productive coal-measures 
beneath the secondary rocks of the eastern and south-eastern counties. A 
new boring has actually been commenced near to the old one, and a depth of 
40 feet has been reached. 
Geological Society of London.—At the Annual General Meeting of this 
Society, held on February 19, Mr. John Evans, F.R.S., President, in the Chair, 
the Wollaston Gold Medal was presented to Professor de Koninck, in 
recognition of his extensive paleontological researches, especially among 
the Carboniferous rocks. The balance of the proceeds of the Wollaston 
Donation Fund was awarded to Mr. L. C. Miall, to assist him in his 
researches on Fossil Reptilia. The Murchison Medal was presented to Mr. 
W. Jory Henwood, F.R.S., &c., as a mark of the Society’s appreciation of his 
observations on metalliferous deposits; and the Murchison Geological Fund 
was presented to Professor H. G. Seeley, in recognition of his various paleon- 
tological researches. In his address, Mr. Evans discussed the geological 
evidence of the antiquity of the human race. 
PHYSICS. 
LiGHT.—Writing to the ‘‘Chemical News,’? Mr. W. H. Olley draws 
attention to an adaptation which he made, about two years since, of polarised 
light to the well-known and beautiful optical instrument, the kaleidoscope. 
This instrument, it need hardly be observed, consists of a tube, within which 
are fixed, at an angle representing an aliquot part of a circle, two or three 
plane mirrors, blackened on the outside, so as to give by repeated reflection 
symmetrical and constantly varying images of pieces of coloured glass or 
other transparent objects, placed in a cell at one end of the tube, the images 
being viewed through a small aperture at the opposite end. It occurred to 
Mr. Olley that if pieces of selenite were substituted for the fragments of 
coloured glass, and polarised light were made to pass through the instrument, 
there would be seen, with the aid of an analyser, the beautiful colours given 
by that familiar double-refra&ting substance, reflected like those of ordinary 
light. Accordingly he selected films of selenite, presenting, when analysed, 
various colours corresponding with their respective thickness, and mounted 
them on pieces of thin crown glass of different shapes and sizes, placed them 
in the cell of a kaleidoscope, and adapted a tube to the other end so asto 
receive a second tube fitted with a small Nicol prism, or a tourmaline. He 
then found that when light polarised by a plate of glass, or even by a cloud- 
less sky, was transmitted through the cell, the reflected images of the selenite 
mountings were symmetrically and beautifully displayed. To enlarge these 
polarised images, and to increase the strength of their colours by concen- 
trating the rays, he adapted in some of the instruments a lens of appropriate 
focus to the eye-end of the tube just below the Nicol, or analyser, but this 
~ addition is not necessary. 
