Jan. 30, 1890] 



NATURE 



311 



freshwater genus, and inquired whether the fossil fish was fresh- 

 water or marine. Mr. E. T. Newton remarked upon the great 

 interest and importance of the paper. The author, in reply to 

 the President's question, said that the old Ganoids were marine, 

 and it was only in more recent times that they had become 

 restricted to fresh water. — On the Pebidian volcanic series of St. 

 David's, by Prof. C. Lloyd Morgan. After a brief sketch 

 of the principal theories that have been propounded, the 

 author concluded that our knowledge of this series has not 

 yet reached "a satisfactory position of stable equilibrium." 

 His own communication was divided into three sections. 

 The Relation of Pebidian to Catnbrian : There are four locali- 

 ties where the junction is described — Caerbwdy Valley, St. 

 Non's Bay, Ogof Golchfa, and Ramsey Sound. The strati- 

 graphy of the second of these was given with much detail, and 

 illustrated. The author concluded that here, together with 

 clear signs of local or contemporaneous erosion, the general 

 parallelism of the strike of Pebidian and Cambrian is most 

 marked. There is no evidence of any bending round of the 

 conglomerate against the strike of the Pebidians. The strati- 

 graphical evidence in each of the localities having been con- 

 sidered, together with the evidence offered by the materials of 

 the Cambrian conglomerate and local interstratification with the 

 volcanic beds (the interdigitation at Carnarwig being well 

 marked), he concluded that there was no great break between 

 the conglomerate and the underlying Pebidians. The upper- 

 most Pebidian already foreshadowed the sedimentary conditions 

 of the Harlech strata, and the change emphasized by the con- 

 glomerate was one that followed volcanic conditions after no 

 great lapse of time. Hence the relation of the Pebidian to the 

 Canibrian is that of a volcanic series, for the most part sub- 

 marine, to succeeding sedimentary strata — these strata being 

 introduced by a conglomerate formed in the main of foreign 

 pebbles borne onward by a current which swept the surface of, 

 and eroded channels in the volcanic tufifs and other deposits. 

 He was disposed to retain the name Pebidian as a volcanic 

 series in the base of the Cambrian system. The Pebidian Suc- 

 cession : With the exception of some cinder- beds, which appear 

 to be subaerial, the whole series was accumulated under water. 

 There is no justification for making separate subdivisions ; the 

 series consists of alternating beds of tuff of varying colour and 

 basicity, the prevailing tints being dark green, red-grey, and 

 light sea-green. In the upper beds there is an increasing 

 amount of sedimentary material, and more rounded pebbles 

 are found. Basic lava-flows occur, for the most part, in the 

 upper beds. Detailed work, laid down on the 6-inch Ordnance 

 map, appears to establish a series of three folds— a northern 

 anticline, a central syriclin^, 'arid "a southern anticline— folded 

 over to form an isocline, with reversed dips to the south-east. 

 The axis of folding is roughly parallel to the axis of St. David's 

 promontory. The total thickness is from 1200 to 1500 feet. 

 The author devoted a considerable number of pages to further 

 details concerning this series of deposits. He failed to find the 

 alleged Cambrian overlap. " The probabilities are that it is by 

 step-faults brtween Rhoson and Porth Sele, and not by overlap, 

 that the displacement of the conglomerate has there been 

 effected." Also at Ogof Goch it does not rest upon the quartz- 

 felsite breccia and sheets (group C, of Dr. Hicks), but is faulted 

 against them. A section was devoted to the felsitic dykes, and 

 it was suggested that they may be volcanic dykes of Cambrian 

 age. The Relation of the Pebidian to the Dimetian : The 

 author has not been able to satisfy himself of the existence of 

 the Arvonian as a separate and distinct system. He notes the 

 junction of Pebidian and Dimetian in Porthlisky Bay and the 

 Allen Valley at Porth Clais, at neither of which places are there 

 satisfactory evidences of intrusion. At Ogof Llesugn the in- 

 trusive character of the Dimetian was strongly impressed upon 

 him. He criticized the mapping of Dr. Hicks, and pointed out 

 the difficulties which present themselves in the way of mapping 

 the Dimetian ridge as pre-Cambrian. He pointed out that not 

 a single pebble of Dimetian rock, such as those now lying on 

 the beach in Porthlisky Bay, is to be found in the conglomerate. 

 He concluded that the Dimetian is intrusive in the southern 

 limb of the isocline, and that there are no Archaean rocV%insitu. 

 After the reading of this paper there was a discussion, in which 

 the President, Dr. Hicks, Prof. Blake, Prof. Hughes, and Mr. 

 ■Wuhams took part. 



Sydney. 

 Royal Society of New South Wales, November 6, 1889. 

 —Monthly meeting. ^Prof. Liversidge, F.R.S., President, in 



the chair. — The Chairman announced the death of the Rev. J. 

 E. Tenison-Woods, who had been an honorary member of the 

 Society since 1875.— The following papers were read :— Aids to 

 the sanitation of unsewered districts, poudrette factories, by 

 Dr. J. Ashburton Thompson. — Notes on Goulbum lime, by 

 E. C. Manfred'.— Notes on some minerals, &c., by John C. H. 

 Mingaye. 



December 4.— Monthly Meeting;. — Prof. Liversidge, F.R.S., 

 President, in the chair. — The following papers were read: — 

 Well and river waters of New South Wales, by W. A. Dixon. 

 — The Australian aborigines, by Rev. John Mathew. 



Paris. 



Academy of Sciences, January 20. — M. Hermite in the 

 chair. — On the various states of the carbon graphites, and on the 

 chemical derivatives corresponding to them, by MM. Berthelot 

 and P. Petit. The graphites, when oxidized by the wet process 

 at a low temperature, form ternary compounds, one of whose 

 terms has been discovered by Brodie. But M. Berthelot has 

 since shown that there exist several chemically distinct graphites, 

 each forming a particular graphitic oxide, which yields a corre- 

 sponding hydrographitic and pyrographitic oxide, and which may 

 be recovered with all their primitive properties. These various 

 graphites and the series of corresponding compounds have been 

 studied, first by their composition and behaviour, and in a 

 second memoir by the measurement of the heats of combustion 

 and formation. — Remarks on the formation of the nitrates in 

 plants, by M. Berthelot. The author points out that the facts 

 established by Haeckel and Lundstrom, taken in connection 

 with his own observations, tend to show an affinity between the 

 microbes present in the soil and those developed in the plant. 

 This applies to the microbes which fix the nitrogen of vegetable 

 humus and the leguminous plants, as well as to those which 

 similarly form the nitrates in amaranthus, sterculia, the coffee 

 shrub and vegetable humus.— Note on a fundamental point of 

 the theory of polyhedrons, by M. de Jonquieres. The paper 

 deals with Euler's famous formula S + H = A 4- 2, and shows- 

 that it is applicable, and intended by Euler to be applicable, to 

 all polyhedrons without exception, and not restricted to any 

 particular class, as supposed by Legendre, Cauchy, and others. 

 — Ephemerides for the search of the periodical comet of d'Arrest 

 on its return in 1890, by M. Gustave Leveau. Having previously 

 obtained the elements for the years 1870, 1877, and 1883, by 

 allowing for the disturbing influence of Jupiter, Saturn, and 

 Mars, M. Leveau here supplies those for 1890 (February 25, 

 mean Paris time) by studying the disturbing effects produced by 

 Jupiter in the interval between 1883 and 1890.— Observations of 

 Swift's comet made at the Observatory of Nice with the 0*38 m. 

 equatorial, by M. D. Eginitis.— On the solar statistics for the 

 year 1889, by M. Rud. Wolf. From the solar observations made 

 at Zurich and the magnetic observations recorded at Milan, the 

 author has constructed a table of monthly means showing that 

 both the relative numbers and the magnetic variations have con- 

 tinued to diminish during 1890. But he thinks that the retro- 

 grade movement will soon cease, and that we probably entered 

 the minimum period towards the end of last year. — On the 

 theory of the figure of the planets, by M. M. Hamy. An 

 attempt is here made to realize theoretically the conditions of a 

 system answering to M. Poincare's remarkable theorem published 

 in the Comptes rendus for June 1888. — On the integration of an 

 equation with partial derivatives, by M. Zaremba. The paper 

 deals with an equation of the form 



cPx 

 dxdy 



+ <^l(-+>')(i + |)+«^2(^-+.^)-0. 



where <^-^ and (^.^ are two functions whatsoever oi x ■\- y, and 

 shows that the determination of the general integration may be 

 reduced to the integration of an ordinary linear differential 

 equation of the second order, and to quadratures. — On the varia- 

 tion of the resistance of bismuth in the magnetic field, by M. A. 

 Leduc. The author here continues his studies of the electric 

 resistance of bismuth as affected by varying temperature. — 

 Calculation of the compressibility of nitrogen up to 3000 atmo- 

 spheres, by M. Ch. Antoine. The results of fresh calculations 

 are here summed up in a table resuming all the data relative to 

 the pressure of nitrogen up to a pressure of 3000 atmospheres. — 

 On the combinations of the metals of the alkalies with ammonia, 

 by M. H. W. Bakhuis Roozeboom. An explanation is offered of 

 the curious phenomena mentioned by M. Joannis in his recent 



