Dec. 20, 1888] 



NATURE 



89 



for the collection of eighty or a hundred specimens of extremely 

 rare varieties. The Committee hoped to present a report next 

 year. 



At the conclusion of the Conference, votes of thanks were 

 I'assed to the Chairman and Secretary. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 

 Cambridge. — The Sheepshanks Astronomical Exhibition at 

 Trinity College, open to the competition of any undergraduate 

 of the University, has been awarded to Frank Watson Dyson 

 and Gilbert Thomas Walker, brother scholars of the College, 

 who are declared to be equal in merit. The value of the Ex- 

 hibition is 50/. per annum, tenable for three years, and it will 

 be divided between the successful candidates. 



SCIENTIFIC SERIALS. 



American Jotu-nal of Scioice, December. — The invisible solar 

 and lunar spectrum, by S. P. Langley. This paper, which is 

 an abstract of a memoir about to appear in the publications of 

 the United States Academy of Sciences, summarizes the result 

 of investigations carried on at the Allegheny Observatory in 

 continuation of the author's previous researches on the infra-red 

 of the solar spectrum to the extent of about three microns. By 

 means of the improved apparatus here described, the extreme 

 infra-red solar spectrum has now been searched from three to 

 over eighteen microns ; and it is shown that in this region the 

 ratios between solar and lunar heat are completely changed from 

 what they are in the visible spectrum. While the solar light in the 

 latter is about 500,000 times that of moonlight, the solar heat re- 

 ceived in the invisible part of the spectrum is probably less than 

 500 times the lunar. These studies also promise important 

 results for meteorology, by opening to observation the hitherto 

 unknown region of the spectrum, in which are to be found the 

 nocturnal and diurnal radiations, not only from the moon towards 

 the earth, but from the soil of the earth towards space. — A brief 

 lustory of Taconic ideas, by James D. Dana. The Taconic 

 question is here treated in chronological order from 1818 till the 

 present year, in which the controversy may be regarded as prac- 

 tically closed. The conclusion is now firmly established that 

 this system is not pre-Silurian, but merely another name for the 

 older term " Lower Silurian." — Certain generic electrical rela- 

 tions of alloys of platinum, by C. Barus. In this paper are given 

 the chief results of the investigations on the measurement of 

 high temperatures already described in vol. xxxv. p. 407, of the 

 Journal. The results generally point to a limit below which, in 

 the case of solid metals and at ordinary temperatures, neither 

 electrical conductivity nor temperature-coefficient can be re- 

 duced. It thus appears that a lower limit of l^oth conductivity 

 and temperature-coefficient is among the conditions of metallic 

 conduction, not to say of the metallic state absolutely. — On the 

 Puget group of Washington Territory, by Charles A. White. A 

 careful study of some fossil Mollusca from the coal-bearing 

 formation in the Puget Sound basin, shows that they belong to 

 a hitherto unknown brackish-water fauna, characterizing a 

 deposit of unusual interest. A section of this formation mea- 

 sured at the town of Wilkeson gives a minimum thickness of no 

 less than 13,200 feet, with a probable maximum of 14,500 feet. 

 The surprise caused by the discovery of such an extraordinary 

 thickness in an estuary deposit is increased by the fact that its 

 Molluscan fauna appears to range vertically throughout the whole 

 formation. The fauna itself seems to be of the same age, but 

 distinct from, the Laramie, which flourished, not in an estuary, 

 but in a land-locked basin. The area of the Puget group in- 

 cludes the Cascade Range, but is not otherwise yet clearly defined 

 eastwards from the Pacific seaboard. — Papers are contributed 

 )>y L. G. Eakins, on some sulphantimonites from Colorado ; by 

 A. E. Kennelly, on the voltametric measurement of alternating 

 Currents ; by Dr. C. Hart Merriman, on the fauna of the Great 

 Smoky Mountains, with description of a new species of red- 

 backed mouse ; by W. E. Hidden and J. B. Mackintosh, on 

 anerlite, a new thorium mineral ; and by O. C. Marsh, on a new 

 family of horned Dinosaurians [Ceratops montanus) recently dis- 

 covered in situ in the Laramie deposits of the Cretaceous 

 period, in Montana This reptile was a very formidable animal, 

 armed not only with horns of great strength, but with a thick 

 dermil hide, and varying in length from 25 to 30 feet. 



SOCIETIES AND ACADEMIES. 

 London. 

 Royal Society, December 6. — " Some Observations on the 

 i Amount of Light reflected and transmitted by certain kinds of 

 Glass." By Sir John Conroy, Bart., M.A., Bedford Lecturer 

 of Balliol College and Millard Lecturer of Trinity College, 

 Oxford. Communicated by A. G. Vernon Harcourt, F. R.S, 

 Conclusions. — It seems probable that the amount of light re- 

 I fleeted by freshly polished glass varies with the way in which it 

 i has been polished, and that, if a perfect surface could be obtained 

 without altering the refractive index of the surface-layer, then the 

 amount would be accurately given by Fresnel's formula, but that 

 \ usually the amount differs from that given by the formula, being 

 sometimes greater and sometimes less. 



The formation of a film of lower refractive index on the glass 

 would account for the defect in the reflected light ; but to account 

 for the excess, it seems necessary to assume that the polishing has 

 increased the optical density of the surface-layer, and the changes 

 produced in the amount of light transmitted and in the angle of 

 polarization support this view. 



After being polished, the surface of flint glass seems to alter 

 somewhat readily, the amount of the reflected light decreasing, 

 and the amount of the transmitted increasing, whilst with crown 

 glass the change, if any, proceeds very slowly. 



There is no evidence to show to what particular cause these 

 changes are due. 



The values of the transmission coefficients for light of mean 

 refrangibility for the two particular kinds of glass are given, and 

 show that for i cm. the loss by obstruction amounts to 2 "62 

 per cent, with the crown glass and i'i5 per cent, with the flint 

 glass. 



Linnean Society, December 6. — Mr. W. Carruthers, F.R.S., 

 President, in the chair. — Mr. W. H. Beeby exhibited and made 

 some remarks on specimens of Valeriana mikanii and satnbuci- 

 folia, and a series of Potamogeton fluitans. — Mr. F. W. Oliver 

 described the nature and growth of leaf emergences in Eriosper- 

 mum folioliferum. — Mr. E. M. Holmes exhibited specimens of 

 a new Assafoetida plant {Ferula fcetidissi/na), and a monstrosity 

 of Zea Mays. — Mr. J. G. Baker exhibited a curious variety of 

 Vicia sepium, found in North Yorkshire. — Mr. T. Christy 

 exhibited specimens of an undetermined species of Echium 

 received from Persia, and employed medicinally as a good 

 alterative. — The first paper read was one by Dr. Costerus on 

 malformation in Fuchsia globosa, upon which Prof. Bower 

 offered some critical remarks. — The next paper was by Mr. B. 

 T. Lowne, v/ho gave an admirable demonstration of the mode 

 of development of the egg and bUstoderm of the blow- fly. His 

 conclusions were criticized by Prof. Stewart, Prof. Howes, and 

 Mr. A. R. Hammond. — In continuation of the Reports on the 

 collections made by Mr. Ridley in Fernando Noronha, a paper 

 was read on behalf of Mr. Boulenger, enumerating the fishes 

 and reptiles which had been identified by him, 



Physical Society, December 8.— Prof. Reinold, F.R,S., 

 President, in the chair. — The following communications were 

 read : — Note on a modification of the ordinary method of de- 

 termining electro-magnetic capacity, by Dr. J. W. W.Waghorne, 

 — On some facts connected with the systems of scientific units 

 of measurement, by Mr. T. H. Blakesley. — Some improved 

 polarizing apparatus for microscopes were exhibited and de- 

 scribed by Dr. S. P. Thompson. For polarizer, he uses an 

 Ahrens' prism, and for analyzer a flat-ended one of his own 

 design. The Ahrens' prism is formed from a rectangular block 

 of spar, two faces of which are perpendicular to the optic axis ; 

 two cuts parallel to the axis are made from the middle of on e 

 side to the ends of the opposite, and the cut faces are polished 

 and cemented by Canada balsam. A short prism with wide 

 angle is thus obtained, which can be readily fitted to the substage 

 of the microscope. The analyzer, which consists of two wedges 

 of spar, is mounted in a tube which fits on the eye-piece, and by 

 recognizing that the upper end need not be larger than the 

 pupil of the eye, the author has been able to considerably reduce 

 the length of the prism, and still keep the bottom end large 

 enough to collect all the rays passing through the eye-piece. 

 Several ingenious methods of cutting spar so as to produce 

 prisms with minimum waste were described and illustrated by 

 models, and a "Nicol " made by the inventor at the age of 79 

 was exhibited. Mr. Lant Carpenter asked the author why he 

 condemned analyzers placed directly behind the objective, for in 



