Dec. 27, 1877] 



NATURE 



175 



perature of the interior surface of the fly will be less at- 

 tracted, or, which is the same, more repelled. Hence, whether 

 the inner surface of the bulb be cooler or hotter than the 

 fly, a reversal in the direction of rotation while the fly is being 

 heated, indicates a reversal in the order of absorbing power of 

 the two faces, and that, again, shows that the order is different 

 for different components of the total radiation, and that the ratio 

 of the intensity of those components has been changed. 



It is perhaps hardly necessary to observe that the radiometers 

 mentioned in this paper are of the usual form — that is to say, that 

 their arms are symmetrical, so far as figtire is concerned, with 

 respect to a vertical plane passing through the point of support. 

 Accordingly the rotation which is attained, for instance, with a 

 radiometer with concave disks of aluminium, alike as to material 

 on both faces (of which kind, again, I owe a beautiful specimen 

 to Mr. Crookes's kindness), has not been referred to. This rota- 

 tion, depending on the more favourable presentation to the bulb 

 of the outer (and therefore nearer and more efficient) portions of 

 the fly on the convex than on the concave side, has nothing to 

 do with the one isolated subject to which the present paper 

 relates, namely, the elucidation of the peculiar behaviour in 

 certain cases of certain kinds of radiometers, by a consideration 

 of the heterogeneous character of the total heat-radiation. 

 ( To be continued. ) 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



Leeds. — By the liberality of the Worshipful the Drapers' 

 Company, the Council of the Yorkshire College are prepared to 

 appoint an instructor in coal mining at the stipend of 100/. per 

 annum and half the students' fees. A portion only of the 

 instructor's time will be required. The fuller conditions and 

 duties of the office may be learned from the secretary. Applica- 

 tions and testimonials must be received on or before January i8. 



Lexington, U.S. — In connection with the Centennial, efforts 

 have been made in the United States to raise an endowment fund 

 for Washington and Lee University, at Lexington, Va, The in- 

 stitution dates from colonial times, and was endowed, while it 

 was still only an academy, by Washington and other soldiers of 

 the Revolution. Among other recent benefactors of the Uni- 

 versity is Mr. L. J. McCormick, of Chicago, who has offered 

 to give his magnificent telescope, made by Alvan Clark, of 

 Cambridge, U.S., at a cost of 50,000 dols., provided the insti- 

 tution would raise the necessary funds to equip and maintain it. 

 The trustees have not yet been able to do anything towards the 

 acceptance of this proposal. It would be a great misfortune if 

 the conditions could not be complied with, and we hope that the 

 suggestion that the ladies in various parts of the States should 

 take the matter up will be complied with j there is no doubt if 

 they make up their minds to success they will succeed. 



Berlin. — The great Prussian university is closely competing 

 now with the Leipsic University in point of attendance. In the 

 calendar which has just appeared we notice that the number of 

 matriculated students during the present winter amounts to 2,839, 

 an increase of 600 on the summer semester. They are divided 

 among the faculties as follows: theological 168, legal 1,163, 

 medical 345, philosophical 1,163. There are 210 foreigners in 

 the list, including 42 from America. Besides these matriculated 

 students, there are 2,200 other persons in attendance on the 

 lectures, belonging to the various technical and art schools of the 

 city. The corps of instructors numbers 210, nearly half of whom 

 are in the philosophical faculty. 



Bonn. — The winter attendance at the University is 859, an 

 increase of sixty-two on the preceding semester. The philo- 

 sophical faculty includes 375, the legal 219, the medical 126, 

 the Catholic theological, 89, and the Evangelical, 50. 



SOCIETIES AND ACADEMIES 



London 

 Linnean Society, December 6. — Prof. AUman, president, 

 in the chair. — Messrs. J. N. Fitch, J. S. Gamble, F. S. Piggott, 

 A. B. Stewart, and Prof. Macoun were elected Fellows. — Mr. 

 Thiselton Dyer exhibited portions of the " Nam-mu " tree, 

 which grows in Yunnan, 25°-26° N. lat. The Chinese nobility 

 greatly prize its wood for building purposes and for making 

 coffins, and enormous columns in tombs of the Ming dynasty, 300 

 years old, are still extant. Supposed to be teak, it probably 



rather belongs to the Lauracere, the leaves closely resembling 

 those of Phoebe pallida. Mr. Dyer also exhibited a seed of 

 Entada scandens, and another of an anonaceous plant (Cyatho- 

 calyx Maiui^ayi ?) found in the ccccum of Rhinoceros sumalrensis 

 from Chittagong, and dissected at the Zoological Gardens, 

 Regent's Park ; and he likewise showed fruits of Oncocarpns 

 viiiensis from the crop of a fruit-pigeon {Carpophaga latrans). — 

 Attention was afterwards called by Mr. Dyer to the fruit-head 

 of an Indian Pandanns made into a brush, the fibrous tissue of 

 the drupes forming the bristles, and this instrument was said to 

 be used to scrape cloth, like our teazle (Z>/)>ja^«j). — Flowers and 

 foliage of Cinchona (C. calisaya, vars., yosephmna and Anglica) 

 grown in the garden of Mr. J. Elliot, at Tottenham, were ex- 

 hibited by that gentleman, whose researches among the quinine- 

 bearing trees are already well known and appreciated. — Mr. 

 Moggridge read a note on the occurrence at Wallis Down, a 

 heath near Bournemouth, of Dabeocia polifolia. — A paper on 

 certain organs of the Cidaridse was communicated by Mr. Chas. 

 Stewart, who illustrated, amongst others, the subjoined points of 

 his recent investigations. Among the sea-urchins the families 

 Diadematidse, Echinometridoe, and Echinidse, have long been 

 known to possess external branchiae ; but the existence of 

 such in the Cidaridse has been denied by Miiller, though insisted 

 on by Alex. Agassiz. Mr. Stewart finds in Dorocidaris papillata 

 five organs corresponding to branchiae, but situated internally. 

 The water bathing these interior gills finds ingress and egress by 

 a crevice near the " compasses," the peculiar mechanism of the 

 teeth and jaws producing the temporary opening in question. As 

 respects the pedicellarise of Cidaridas, where the jaw ends in a ter- 

 minal hollow fang, there is an additional orifice to that at the tip, 

 besides two glands in the vicinity ; he suggests this to be a 

 poison apparatus, comparable to the falces of the spider, and 

 poison sac and tooth of venomous serpents. — The Secretary read 

 a paper by Dr. I. Bayley Balfour, *' Observations on the genus 

 Pandanns." Few families of plants present more difficulty in 

 their elucidation than the Pandanaceas ; this by variability of 

 species, difficulty of procuring the male flower, with little cha- 

 racter in the leaves, while the fruit loses its distinctive features in 

 drying. The Screw-pines had attracted the notice of the early 

 voyagers, but their descriptions are confused. To Rumphius 

 we owe the name Pandanus, though his account and figures are 

 poor compared with Reede's of a century before. Linnaeus, though 

 indicating a plant under the name Bromelia sylvestris, omitted the 

 genus Pandanus, a want supplied by his son. Afterwards, 

 as species increased, many new genera were unnecessarily intro- 

 duced, which Dr. Balfour is now inclined to reject ; even Brong- 

 niart's New Caledonia genera do not claim acceptance. Panda- 

 nus runs over a great breadth of longitude, viz., from east 

 tropical Africa through the Mascarene Islands, India, Indian 

 Archipelago, and Australia, to the Sandwich Islands. The 

 East Archipelago and the Mascarenes are centres whose species 

 do not commingle. There succeeds in this paper other facts and 

 an extensive list of names and references to all the Pandani 

 known. — The substance was given of a report on a small col- 

 lection of insects obtained by Dr. J. C. Ploetn, in Java, with 

 description of a new species of Hoplia, by Chas. O. Wdterhouse, 

 of the British Museum. — The Secretary read a communication 

 by Dr. J. Stirton, viz., "Notes on the Rev. Mr. Crombie's paper 

 on the Lichens of the C^a/Zifw^i^r Expedition," and another note by 

 Dr. R. C. A. Prior, relative to the migration of wild geese, pur- 

 ported to have passed from North America to the African coast. 



Physical Society, December 15. — Prof. G. C. Foster, pre- 

 sident, in the chair. — The following candidates were elected 

 Members of the Society : — W. E. Ayrton, J. M. Cameron, J. W. 

 Clark, J. E. Judson, B.A., H. N. Moseley, M.A., F.R.S., 

 Lord Rayleigh, M.A., F.R.S., W. N. Stocker, M.A., and 

 H. T. Wood.— Mr. C. W. Cooke read for the author. Prof. 

 S. P. Thompson, a paper on permanent Plateau films, and 

 exhibited the process of their formation. After a brief enumera- 

 tion of the various attempts made by Plateau himself, Schwartz, 

 Mach, Rottier, and others, most of which are described in the 

 work of Plateau, the author described his own experiment on 

 the subject. As the result of these he concludes that the best 

 films are obtained by using a mixture of 46 per cent, of pure 

 amber-coloured resin, and 54 of Canada balsam, which should 

 be heated to from 93° to 95° C. The frames for forming the 

 films are made of brass wire 0*3 mm. in diameter, and when 

 thicker wire is employed they are found to be irregular in 

 consequence of the retention of heat by the metal. The films 

 are obtained by simply introducing these frames into the heated 



