May 2 1, 1874] 



NATURE 



57 



The peculiar winter climate of Davos appears to depend upon 

 the following conditions : — 



1. E/t'i'alwn al'OTe t/ic Sea, Vihizh csLMSts greater rarity of the 

 air, and consequently less abstraction of heat from the body, and 

 also secures greater transcalency in the atmosphere by a position 

 above the chief region of aqueous precipitation, and compara- 

 tively out of the reach of the dust and fuliginous matters which 

 pollute the lower stratum of the air. 



2. T/iiik and (during the winter months) permanent snow, 

 which reflects the solar heat and prevents the communication of 

 warmth to the air, and consequently the production of atmo- 

 spheric currents. In still, though cold, air the skin is less 

 chilled th.in in much less cold air, wliich impinges with consider- 

 able velocity upon the surface of the body. The effect of 

 motion through the air upon the sensation of warmth and cold at 

 Davos is very striking. Mtting perfectly still in the sunshine, 

 the heat in mid-winter is sometimes almost unbearable ; on 

 rising and walking about briskly, a delicious feeling of coolness 

 is experienced, but on driving in a sledge the cold soon becomes 

 painful to the unprotected face and hands. 



3. A sheltered position fa7'ourablc for reesiving both the direct 

 and rejh'ctcd solar rays. — In this respect Davos-Ddrfli, situated 

 opposite to the entrance of the Dischina valley, has the advan- 

 tage over Davos-Plalz two milf s lower down the valley, in which 

 latter village the sun rises on December 21 ih. 9m. later, and 

 sets about ten minutes earlier than at Dcirfli. 



All the.^e conditions contribute not only to a high sun-tem- 

 perature during the winter months, but also to a comparatively 

 uniform radiant heat from sunrise to sunset. 



Addition to the paper. Volcanic Energy : an attempt to 

 develop its true Origin and Cosniical Relations, *„by Robert 

 Mallet, C.E., F.R..S., &c. 



Referring to his original paper (Phil. Trans. 1873), the author 

 remarks that Irom the want of necessary data he had refrained 

 from making any calculation as to what amount in volume of the 

 solid shell of our earth must be crushed annually, in order to 

 admit of the shell following down after the more rapidly con- 

 tracting nucleus. This calculation he now makes upon the basis 

 of certain allowable suppositions, where the want of data requires 

 such to be made, and for assumed thicknesses of solid shell of 

 100 

 200 



400 and 

 800 miles respectively. 



Me tabulates his results for these four assumed thicknesses of 

 shell, and shows that the amount of crushed and extruded rock 

 necessaiy for the supply of heat, for the support of existing vol- 

 canic action, is supplied by that extruded from the shell of 

 between 600 and 800 miles thick, and that the volume of mate- 

 rial, heated or molten, annually blown out from all existing 

 volcanic cones, as estimated in his former paper, could be sup- 

 plied by the extiiided matter from a shell of between 200 and 400 

 miles in thickness. 



On data, which seem tolerably reliable, the author has further 

 been enabled to calculate,as he believes for the first time, the actual 

 amount of annual contraction of our globe, and to show that if 

 that be assumed constant for the last 5, 000 years, it would amount 

 to a little more than a reduction of about 3'5 in. on the earth's 

 mean radius. This quantity, mighty as are the effects it pro- 

 duces as the efhcient cause of volcanic action, is thus shown to 

 be so small as to elude all direct astronomical obserTation, and, 

 when viewed in reference to the increase of density due to refri- 

 geration of the material of the shell, to be incapable of produc- 

 ing, during the last 2,000 years, any sensible effect upon the 

 length of the day. The author draws various other conclusions, 

 showing the support given by the principal results of this entirely 

 independent investigation, to the verisimilitude of the views 

 contained in his previous memoir. 



Linnean Society, May 7. — G. Busk, vice-president, in the 

 chair. — Prof. Thiselton Dyer exhibited a fruit of Tclfairia oeei- 

 dtntalis Hook, f , the seeds of which are used parched by the 

 natives of Calabar, and the young leaves and shoots much prized 

 as a green vegetable. The native name is Ubong. With refer- 

 ence to the fruit of the Aristolechio, hitherto undescribed. Dr. 

 Thomson writes as follows : — " I have seen it, but only so far 

 back as 1859. ... I cannot trust myself to say more than that the 

 fruit was of a red-brown colour, 5 or 6 in. long, and six-celled, with 

 six well-marked ridges."— Mr. J. R. Jackson exhibited a piece of 

 copal from Zanzibar riddled by ants. After having been some time 

 ' Read June 20, 1873 ;'Phil. Trans, for 1873, p. 147. 



in the KewMuseum, the living creature was found in the cojjal aixl 

 sent to Mr. Walker, who determined it to be a species of Tenna 

 or white ant, Eutermes nemoralis Walk. — The following papers 

 were then read, viz. :— On the discovery of Phylica arborea, a 

 tree of Tristan d'Acunha, in Amsterdam Island, in the South- 

 Indian Ocean ; with an enumeration of the Phanerogams and 

 vascular Cryptogams of that island and r)f St. Paul's, by Dr. 

 J. D. Hooker, vice-president. Labillardiere stated in 1791 that 

 the islet of Amsterdam (generally confounded with that of St. 

 Paul), lat. 37° 52' S., long 77° 35' E., in the Indian Ocean, was 

 covered with trees, while that of St. Paul, oidy 50 miles south of 

 it, is destitute of even a shrub. The nature of this arborescent 

 vegetation was unknown until H.M.S. Ptarl touched at the 

 island in the summer of 1873, when Commodore Goodenough 

 brought off a specimen of what he states to be the only tree 

 growing in the island, together with a fern in an imperfect state. 

 The former proves to be the Phylica arborea, of Tristan d'Acunha, 

 and the fern a frond of a Loniaria. Amsterdam Island and 

 Tristan d'Acunha are separated by about 5,000 miles of ocean, 

 and are nearly in the same latitude ; and Dr. Hooker" discusses 

 the various hypotheses which suggest themselves to account for 

 the extraordinary fact of the occurTence of the same species in 

 such widely separated localities. Near the hot springs on St. 

 Paul's Island Lycopodium cernumn is found, an interesting ex- 

 ample of the occurrence of a tropical species under special con- 

 ditrons beyond its normal range, a phenomenon of which other 

 instances also occur. — Additions to the lichen flora of New Zea- 

 land, by Dr. J. Stirton. Communicated by Dr. Hooker-, vice- 

 president. The lichens here described were collected by John 

 Buchanan, of the Colonial Museum, Wellington, N.Z., and in- 

 clude a large number of species now described for the first time. ' 

 — Enumeralio muscorum Cap. Bona: Spei, by J. Shaw. The 

 general results arrived at in this paper are summed up as follows : 

 — (i) The great majority of the Cape mosses are of northern- 

 hemisphere types, a few being cosmopolites. (2) Some Australian 

 and New Zealand forms are represented ; a much larger propor- 

 tion than is the case with flowering plants. (3) Many forms are 

 strictly localised to particular soils and conditions of climate. 

 (4) The moss flora of the Cape is characterised by an almost 

 total absence of Alpine forms. — Contributions to the botany of 

 the Challenger expedition : — No. XV. Notes on Plants collected 

 in the islands of the Tristan d'Acunha group, by H. N. Moseley. 

 Communicated by Dr. Hooker. No. XVI. List of alga; collected 

 by Mr. H. N. Moseley at Tristan d'Acunha, by Dr. G. Dickie. 

 Two new species are described. — On a new Australian Sphaero- 

 moid (Cyclura venosa) ; and notes On Dynamene rubra and D. 

 viridis, by the Rev. T. R. R. Stebbiirg. Communicated by W. 

 W. Saunders. This form belongs apparently to a new genus. 

 It was found in Sydney Harbour, rrnder stones at the lowest ebb- 

 tides. — Descriptions of five new species of Gonyleptcs, by A. G. 

 Butler. These are addrtional to the monograph of the genus 

 already published by the writer. — Observations on the fruit of 

 Nitophyllum versicolor, by Mrs. Merrifield. Communicated by 

 the secretary. The paper contains a description of the coccidia 

 of this species hither to unknown, although the plant was described 

 in 1800. — On Hieracium silhe.'ensc DC, hy C. B. Clarke. The 

 writer disagrees with Vr. Beniham's identification of this species 

 with Ainsliaa angustifolia Hook. f. et Thoms. — Notes on Indian 

 Gentianacece, by C. B. Clarke. — On some Atlantic Crustacea from 

 the Challenger expedition, by R. von Willemoes-Suhm. Commu- 

 nicated by Prof Wyville Thomson, F.R.S. The paper is divided 

 into seven parts as follows :— (I) On a blind deep-sea Tanaid ; 

 (2) On Cysiesoma neptnni ( Thanmops pellucida) ; (3) On a Nebalia 

 Uoxa Bermudas ; (4) On some genera of Schizopoda with a free 

 dorsal shield ; (5) On the development of a land-crab ; (6) On a 

 blind deep-sea Astacus ; (7) On IVillemoesia (Grote), a deep-sea 

 Decapod allied to Cryon. 



Anthropological Institute, May 12. — Prof. Busk, F.R.S., 



president, in the chair. — Messrs. R. and S. Garrard and Co., of the 

 Haymarket, exhibited a very interesting collection of gold ob- 

 jects recently brought from Ashanti. In the discussion Col. 

 Harley, C.B., stated that the Ashantis, and indeed all the 

 tribes of and near the coast, could originate nothing ; they were 

 simply copyists, and from frequent repetition of European mode!'-. 

 asweU asof natural objects, they often attained greatskill in the art. 

 — Mr. Francis Galton gave some results of school statistics 

 which he had obtained from Marlborough and Liverpool 

 Colleges. If his applications for co-operation from other 

 head-masters and assistant-masters were equally successful 

 as from these two, he would soon have sufficierit material 



