July 15, iSSoJ 



NATURE 



259 



u^Tly = ^ X 378819 ,.980856. 

 ye 772 X 463-2 



The letter « in the paper with the value obtained as above is 

 applied in the following remarkable generalisations : m being 

 the molecular weight of the substances, and / v and 6 being the 

 pressure, volume, and absolute temperature in any standard units. 



The thermal equivalent of pv = ~ 6, 

 m 



Specific heat at constant volume = 2i - 9 



Specific heat at constant pressure = 3^—9 



The specific heat in the gaseous state is therefore at constant 

 pressure. 



3i X 1-989856 _ . 



17-96 - ^**"^^ 



for HjO, water in the gaseous state. By calculating the difference 

 of entropy for water at numerous temperatures for the different 

 sta*es of aggregation, fir.-t absolute HoO without energy volume, 

 secondly, water as we know it with a volume increasing with 

 temperature ; thirdly, water split into single molecules, but these 

 yet without motion ; fourthly, single molecule HjO or steam 

 gas ; he shows that the difference of entropy between ihe third and 

 the fourth state is equal to the specific heat at constant pressure, 

 and that the whole energy possessed by the water up to the split 

 and motionless stale is a constant quantity at all temperatures for 

 the same substance. He calls this quantity the absolute splitting 

 heat ; the splitting heat above any standard state he calls the 

 nominal splitting heat, .Ja constant quantity for all temperatures. 

 From the entropy calculation for more than twenty temperatures, 

 all calculate to seven places of decimals from Regnault's exact 

 formula (H) for saturated steam, he takes two temperatures 

 indiscriminately, and equates the value of ^ expressed in entropy 

 quantities with one unknown quantity, the specific heat entropy. 

 Equating 278° C. with 374° C. gives ... "387729 

 ,, 278" C. with 494° C. gives ... "387867 



Mean calculated specific heat 

 Instead of 



2 ) -775596 



-387798 

 -387779 



Difference -000019 



The value of i" above melted ice is for water 



Calculated at 278° 5" = 502-386 



„ 294° 6- = 502-405 



2)1004-791 



502 395 C. 

 or 904-311 F. 

 This is a remarkable corroboration of the kinetic theory of 

 gases, quite unlooked for in steam experiments, and, as the 

 author of the paper remarked, it shows how reliable are the 

 results of the experimenter Regnault. The author also explained 

 a new diagram, in which the area is energy, the length entropy, 

 and the height temperature. In such a diagram it becomes as 

 simple an idea as temperature. From this it appears that the 

 ratio of the two specific heats is I -4 for steam. — Mr. Clark com- 

 municated a paper on the behaviour of liquids and gases near 

 their critical temperatures. — Mr. Winstanley exhibited two new 

 varieties of air-thermometers and a thermograph actuated by an 

 air-thermometer on the principle of his radiograph exhibited at 

 last meeting. The first thermometer consists of a (J tube with 

 terminal bulbs and the left leg of much finer bore than the right. 

 Mercury is in the right leg, sulphuric acid surmounted with air 

 in the left. The apparatus is a barometer to the air inside the 

 left bulb, and a thermometer to that outside. A similar com- 

 bination of an air-thermometer and an aneroid barometer consti- 

 tutes the second instrument. The expansion or contraction of the 

 air in the stem by external temperature expands or compresses 

 a small aneroid chamber in the bulb. — Mr. Gee and Mr. Stroud 

 made a communication on a modification of Eunseu's calori- 

 meter, which will be found in the Proceedings of the Society. — 

 The meeting then adjourned till the winter session commences. 



Geological Society, June 23. — Robert Etheridge, F.R.S., 

 president, in the chair. — Edwin Muir, Benjamin Sykes, and 



John Thorburn were elected Fellows of the Society. The fol- 

 lowing commnnications were read : — On the skull of an Ichthyo- 

 saurus from the lias of Whiiby, apparently indicating a new 

 species (/. zetlandkus, Seeley), preserved in the Woodwardian 

 Museum of the University of Cambridge, by Prof. II. G. Seeley, 

 F.R.S. — Note on the cranial characters of a large Teleosaur 

 from the Whitby lias, preserved in the Woodwardian Museum 

 of the University of Cambridge, by Prof. II. G. Seeley, F.R.S. 

 — On the discovery of the place where Pak-eolithic implements 

 were made at Crayford, by F. C. J. Spurrell, F.G.S.— The 

 geology of Central Wales, by Walter Keeping, F.G.S., with 

 an appendix by C. Lapworth, F.G.S., on a new species of 

 Cladophora .—On new Erian (Devonian) plants, by J. W. Daw- 

 son, F.R.S. The paper first referred to recent publications 

 bearing on the Erian (Devonian) flora of North-East America, 

 and then proceeded to describe new species from New York 

 and New Brunswick, and to notice others from Queensland, 

 Australia, and Scotland. The first and most interesting is a 

 small tree-fern, Asteropleris noveboraccnsis, characterised by an 

 axial cylinder composed of radiating vertical plates of scalariform 

 tissue imbedded in parenchyma and surrounded by an outer 

 cyhnder penetrated with leaf -bundles with dumb bell-shaped 

 vascnlar centres. The specimen was collected by Mr. B. Wright 

 in the Upper Devonian of New York. Another new fern from 

 New York is a species of Equisetides (E. n'rightianiitn), show- 

 ing a hairy or bristly surface, and sheaths of about twelve short 

 acuminate leaves. A new and peculiar form of wood, obtained 

 by Prof. Clarke of Amherst College, Massachusetts, from the 

 Devonian of New York, was described under the name Cellu- 

 loxyloH frinuTvum. It presents some analogies with Prolo- 

 laxiles and with Aphylliim paradoxum of Unger. Several new 

 ferns were described from the well-known Middle Devonian 

 plant-beds of St. John's, New Brunswick ; and new facts were 

 mentioned as confirmatory of the age assigned to these beds, as 

 showing the harmony of their flora with that of the Erian of 

 New York, and as illustrating the fact that the flora 1 f the 

 Middle and Upper Devonian was eminently distinguished by 

 the number and variety of its species of ferns, both herbaceous 

 and arborescent. It will probably be found eventually that in 

 ferns, equisetaceous plants, and conifers, the Devonian was 

 relatively richer than the Carboniferous. Reference was also 

 made to a seed of the g.enus .'Etheotesla of Charles Brongniart, 

 found by the Rev. T. Broun in the Old Red Sandstone of Perth- 

 shire, Scotland, and to a species of the genus DicranophyUum 

 of Grand'-Eury, discovered by Mr. J. L. Jack, F.G.S., in the 

 Devonian of Queensland. In all, this paper added six or seven 

 new types to the flora of the Erian period. Several of them 

 belong to generic forms not previously traced further back than 

 the Carboniferous. The author uses the term " Erian " ior that 

 great system of formations intervening in America between the 

 Upper Silurian and the Lower Carboniferous, and « liich, in the 

 present uncertainty as to formations of this age in Great Britain, 

 should be regarded as the type of the formations of the period. 

 It is the " Erie Division " of the original Survey of New York, 

 and is spread around the shores of Lake Erie, and to a great 

 distance to the southward. — On the terminations of some Ammo- 

 nites from the inferior oolite of Dorset and Somerset, by James 

 Buckman, F. L.S. — Faroe Islands : Notes upon the ccal foimd 

 at Suderbe, by Arthur H. Stokes, F.G.S. — On some new creta- 

 ceous Co!Jia/i<l,e, by P. Herbert Carpenter, M.A. Communi- 

 cated by Prof P. Martin Duncan, F.R.S.— On the Old Red 

 Sandstone of the north of Ireland, by F. Nolan, M.R.I. A. 

 Communicated by Prof. Hull, F.R.S. — A review of the family 

 Vincularidje, recent and fossil, for the purpose of classification, 

 by G. R. Vine. Communicated by Prof. P. M. Duncan, F.K.S. 

 — On the zones of marine fossils in the calciferous sandstcne 

 series of Fife, by James W. Kirkby. Communicated by Prof. 

 T. Rupert Jones, F.R.S — The glaciation of the Orkney Islands, 

 by B. N. Peach, F.G.S., and John Home, F.G.S. In this 

 paper, which forms a sequel to their description of the glacia- 

 tion of the Shetland Isles, the authors, after sketching; the 

 geological structure of Orkney, proceeded to discuss the gjacial 

 phenomena. From an examination of the various striated sur- 

 faces they inferred that the ice which glaciated Orkney must 

 have crossed the islands in a north-westerly direction from the 

 North Sea to the Atlantic. They showed that the <lispersal of 

 the stones in the houlder-clay completely substantiates this con- 

 clusion ; for in Westray tlris deposit contains blocks of red 

 sandstone derived from the Island of Eda, while in Shapincha 

 blocks of slaggy diabase, occurring in situ on the south-east 



