March 25, 1875J 



NA TURE 



417 



not only by the liberation of heat, but also by the sudden diminu- 

 tion of pressure, which causes an inflow of air and vapour. 3. 

 When different gases and vapours are at rest next each other, they 

 mix and diffuse thoroughly till the mixture becomes homogeneous. 

 Hence it follows : (i) That the permanent gases, of which air 

 consists, are not independent atmospheres, but thoroughly pene- 

 trate each other. This result is confirmed by all experiments, 

 which show the composition of the air at all attainable heights to 

 be the same. (2) That the ceaseless evaporations and condensa- 

 tions render impossible the existence of an independent vapour 

 atmosphere, or of a homogeneous mixture of vapour with the per- 

 manent gases, and cause a rapid decrease of vapour pressure 

 with increase of height. (3) It is not permissible to subtract the 

 tension of vapour from the height of tlie barometer, in order 

 to find the pressure of dry air. — An article follows in the Kleincye 

 Alittheiliingcn on the law of Dalton, respecting the independence 

 of gas atmospheres, and on the composition of the air at great 

 heights. The researches of Maxwell, Boltzmann, and especially 

 of Stefan, lead to these results : The definitive equilibrium of a 

 gas is determined by the law of Dalton, but not the manner in 

 which the gas disposes itself before it has come to equilibrium. 

 According to that law the mixture of two gases would take place 

 with great rapidity, while experience shows the process to be 

 very slow. The subtraction of vapour-tension from the height of 

 the barometer is a false application of the law, and a reading 

 thus corrected has a purely local signification in the narrowest 

 sense. 



The four numbers of the Nnovo Giornale Botanico lialiano for 

 1874 contain the results of a good deal of work done by Italian 

 botanists, though several of the papers are by Russians, and are 

 printed in Ftench. A large proportion of the papers in this vol. vi. 

 relate to Cryptogams ; including one by Prof. Tchistiakoff on 

 the development oi the sporangia and spores in Polypodifcete ; by 

 G. Arcangeli, on certain Fungi of the neighbourhood of Leg- 

 horn, and on Alga,' of the group Ca?loblastie ; by N. Sarokin, 

 on the development of Hormidiuni -'ariiim, an Alga belonging 

 to the family Ulolhricaccae ; and by Prof. Tchistiakoff on the 

 development of the spores of ,A'//7//jr/ww Uniosuui &wA Lycopodiu m 

 alpinum, the subject being treated both in this and the previous 

 paper by the same writer as a contribution to thehitlory of the 

 vegetable cell. — V. Cesatihasa paper on hybridisation in the genus 

 Achillaa, and on the gemmiparous leaves of Cardainiiic pralcnsis. 

 There is a useful bibliography in each number, and we have a 

 report of the proceedings of the Botanical Congress held at 

 Lucca in 1843. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, March 18. — "Report on Observations of 

 the Transit of Venus made at Luxor, Upper Egypt, 19th 

 December, 1874." By Vice-Admiral E. Ommanney, C.B., 

 F.R.S. 



" Preliminary Abstract of Approximate Mean Results with 

 the Invariable Pendulums Nos. 4 and 1821, in continuation of 

 the Abstract published in vol. xix. of the Proceedings." By 

 Captain W. J. Heaviside, R.E. Communicated by Professor 

 Stokes, Sec. R.S. 



Linnean Society, March iS. — Dr. G. J. AUmann, F.R.S., 

 president, in the chair. — Mr. Rotheiy exhibited a convenient 

 apparatus for drying plants when on a walking expedition. — The 

 following papers were read : — On thiity-one new species of 

 marme Planarians from the Eastern Seas, by Dr. CoUingwood. 

 On the resemblances of Ichthyosaurian bones with the bones 

 of other animals, by Mr. H. G. Seeley. 



Geological Society, March 10. — Mr. John Evans, V.P.R.S. 

 president, in the chair. — The following communication was 

 read :^" The Rocks of the Mining Districts of Cornwall, and 

 their relation to Metalliferous Deposits," by I\lr. John Arthur 

 Phillips, M.I.C.E. In this paper the author adduced numerous 

 faets observed by him in the examination of the rocks of the 

 mining districts of Cornwall which led him to the following con- 

 clusions : — The clay-slates of Cornwall differ materially in com- 

 position, but no rearrangement of their constituents could result 

 in the production of granite. Some of the "gieenstones" of 

 the Geological Survey Map are volcanic rocks contemporaneous 

 with the slates among which they are found, whilst others are 

 hornblendic slates, diorites, &c. Granites and elvans having a 

 similar chemical and mineralogical composition were probably 



derived from the same source ; but the volume of the bubbles in 

 the fluid-cavities of both having no constant relation to the 

 amount of liquid present, do not afford any reliable data from 

 which to calculate the temperatures at which these rocks were 

 respectively formed. The stone-cavities of elvans, and probably 

 of some other rocks, are often the results of the irregular con- 

 traction, before the solidification of the base, of imbedded 

 crystals of quartz. In rocks having a glassy base, glass-cavities 

 will be produced. The vein-fissmes of the tin- and copper- 

 bearing lodes of Cornwall were produced by forces acting after 

 the solidification of the elvans, but in the same general direction 

 as those which caused the eruption of the latter ; and these fis- 

 sures were afterwards filled with minerals deposited by chemical 

 action from water and aqueous vapours circulating through them, 

 but not necessarily at a high temperature. How far these 

 deposits were produced by water rising from below or influenced 

 by lateral percolation cannot be determined ; but the effects pro- 

 duced on the contents of veins by the nature of the enclosing 

 rock, and the occurrence of deposits of ore parallel with the line 

 of dip of the adjoining country, lead to the conclusion that lateral 

 infiltrations must have materially influenced the results. Contact- 

 deposits and "stockwerks" have been formed by 'analogous 

 chemical action, set up in fissures resulting from the junction of 

 dissimilar rocks, or in fractures produced during the upheaval of 

 partially consolidated eruptive masses. The alteration produced 

 in stratified deposits in the vicinity of eruptive rocks is probably 

 often due to similar percolations. It is not improbable that 

 quartz may sometimes retain a certain amoimt of plasticity after 

 it has assumed a crystalline form. 



Zoological Society, March 16.— Dr. A. Giinther, F.R.S., 

 V. P., in the chair. — Mr. Howard Saunders exhibited a specimen 

 of a Gull olitained by Mr. Gervaise M>athew, R.N., at Magda- 

 lena Bay, Lower California, closely resembling Lai us fusctis, a 

 species hitherto unrecorded from the New World.— A letter was 

 read, addressed to the Secretary by Capt. John Biddulph, con- 

 taining remarks on the Wild Sheep met with during his recent 

 journey to Yarkand. — A letter was read from the Rev. J. S. 

 Whitmee, of Samoa, South Pacific, giving particulars as to the 

 occurrence of the Palolo (Palola viridis) on the shores of that 

 island in 1S74. — Prof. W. H. Flower, F.R.S. , read a memoir 

 on the anatomy and affinities of the Musk Deer (Mcschus mos- 

 iJiiftrus). After an exhaustive account of the structure of this 

 animal, based on the examination of a specimen that had recently 

 died in the Society's Gardens, Prof. F'lower came to the conclu- 

 sion that it was most nearly related to the Cavidw, and might be 

 placed within the limits of that family. — A communication was 

 read from the Rev. O. Pickard-Cambridge, in which he gave the 

 description of twenty-four new species of spiders of the genus 

 Erigonc, from France, Corsica, Sicily, Spain, Morocco, and 

 Algiers. — Dr. A. Giinther, F.R.S., read a second report on the 

 collections of Indian Reptiles recently obtained by the British 

 Museum, and described several species as new to science. — A 

 paper was read by Messrs. Sclater and Salvin, containing an 

 account of the bircs collected by Mr. A. Goering on the Sierra 

 Nevada of Merida, and at San Cristoval in Venezuela in 1874. 

 — A communication was read from M. L. Taczanowski, contain- 

 ing the description of a new species of grouse from the moun- 

 tains of Georgia, allied to the Black Grouse, which was proposed 

 to be called Lyiurus inokosiiwiezi. — Mr. A. G. Butler read the 



descripiions of a large number of new species of Sphi)igidce. 



.Sir Victor Brooke gave a notice of a Deer allied to the Fal- 

 low Deer from Mesopotamia, of which he had lately received 

 specimens from Mr. P. J. Robertson. H.B.M. Vice-Consul at 

 Bussorah. For this new form, which is found in the jungles 

 .along the valley of the Euphrates, Sir V. Brooke proposed the 

 name Ccrxiis mcspfo/aiiiiciis. 



Meteorological Society, March 17.— Dr. R. J. Mann, 

 president, in the chair. — The following communications were 

 read :— On the climate of Patras, Greece, during 1873, by Rev. 

 Heibert A. Boys. This year was remarkable for sudden fluctu- 

 ations and great ranges ol temperature ; the lainfall, amounting 

 10 26'I5 inches, was about the average, but the number of wet 

 days (for that place) was great. The summer months, however, 

 were very dry, there being only five days in June, none in July, 

 and one in August, on which rain fell. There was a period of 

 sixty-eight days from June 24 to August 30, without any rain 

 whatever.— On ozone, by Mr. Francis E. Twerolow. This 

 paper gives an account of nearly all that is known of this remark- 

 able substance. An interesting discussion followed the reading 

 of the paper, bearing chiefly upon the amount of oxygen in the 



