4o6 



NATURE 



[Feb. 2 1, 1889 



use of the rooms and apparatus of the Normal School of Science ; 

 (2) to the Council and Officers of the Society for their services 

 during the past year ; and (3) to the Auditors, Mr. Inwards and 

 Prof. Minchin, for examining the accounts. In returning thanks 

 for the Council and Officers, the President attributed the great 

 success of their meetings to the indefatigable zeal displayed by 

 the Hon. Secretaries. — The meeting was then resolved into an 

 ordinary science meeting. — Prof. A. S. Herschel, F.R.S., read 

 a paper on physico-geometrical models, and exhibited a collec- 

 tion of geometrical figure models illustrating elementary forms of 

 crystallographical and chemical form constructions. The subject, 

 he -said, had suggested itself to him as an important one for 

 study some five years ago, from the possibility which he then 

 discovered of effecting a four-limbed mechanical cycle, similar 

 to a thermodynamic cycle, with a conically revolving pendulum, 

 the mathematical conditions of whose motion involved the 

 logarlthum of the circle radius of the knob's revolution, as a 

 ([uantity equivalent to entropy in the thermal cycle. The 

 mechanical cycle may be effected as follows. Suppose the 

 pendulum knob to be revolving at velocity Vj, and radius 7\ ; 

 imagine the controlling force to decrease so that the radius 

 varies from i\ to r,, the velocity remaining constant at V^ ; then 

 increase the controlling force to its original value, and simul- 

 taneously impart velocity to the knob to keep the radius constant 

 at ;-2, the final velocity being Vg. Next, further increase the 

 controlling force so as to cause the radius to decrease to r^ at 

 velocity Vj ; and finally, decrease the controlling force to its 

 initial value, simultaneously retarding the knob till the velocity 

 is Vj at radius r^. The net energy concerned in the operations 



was given as W = (V^^ _ y^) ^ ; where <p = log '^ and the 



cycle affords an illustration of transformation of gyratory motion 

 into energy of reverberatory push along the axis. The logarithm 

 <p is also measured by the area of a hyperbolic sector, and is con- 

 nected (as was shown) with a sector of the circle which a lamp's 

 conical beam would inscribe upon a square glass screen or plate 

 dividing a long room of square cross-section into two parts. The 

 conical beam prolonged through the glass then traces, on the 

 walls beyond, hyperbolas, whose sectors from their summits are 

 related to the circle's corresponding sectors by a well-known 

 hyperbolocyclic trigonometrical connection. From this mode of 

 constructing the connection, and from a discordance which it 

 shows at the asymptote extremities with Euclid's definition of 

 parallel straight lines, the author concludes that cubic space can- 

 not be continuous in its structure, but must be, in a physically 

 constructive sense, like material particles indestructively atomic or 

 molecular. The models showed modes of constructing cubic 

 space in various ways, chiefly by means of tetrahedra, octahedra, 

 and dodecahedra, the common element of form in these being 

 also shown to be the right-angled tetrahedron or " biquoin " 

 obtained by dividing a cube into six equal parts by three planes 

 through its diagonal. A model of Sir W. Thomson's soap foam 

 figure, and some wooden models representing Haiiy's polyhedral 

 atoms and their combinations, were exhibited to illustrate the 

 structural view thus taken of geometry ; and chemical-figure 

 models of the ring of tetrahedral carbon molecules in benzene, 

 and of the asymmetric groups of similar atoms in active and 

 inactive tartaric acid, were shown. 



Zoological Society, February 5. — Dr. St. George Mivart, 

 F.R.S., Vice-President, in the chair. — The Secretary read a 

 report on the additions that had been made to the Society's 

 Menagerie during the month of January 1889. — Mr. Sclater 

 exhibited a living specimen of the Thick-billed Lark {Rham- 

 phocoris clotbeyi) lately received by the Society from Southern 

 Algeria, and called attention to its structural peculiarities. — Mr. 

 G. A. Boulenger read a paper on the species of Batrachians of the 

 genus Rhacophorus, hitherto confounded under the name of 

 R. maciilatus,, and pointed out their distinctions. — Mr. Sclater 

 pointed out the characters of some new species of birds of the 

 family Dendrocolaptidce, which were proposed to be called 

 Upzicerthia bridgesi, Phacellodomus rujipennis, Thripophaga 

 fusciceps, Philydor cervicalis, and Plcolaptes parvU-ostris. — A 

 communication was read from the Rev. O. P. Cambridge on 

 some new species and a new genus of Araneidea. Two of these 

 species {Pachylo/nenus natalensis and Stegodyphus gregarlus) 

 were based on specimens living in the Insect-house in the 

 Society's Gardens. — A communication was read from Prof. F. 

 Jeffrey Bell, containing descriptions of new or rare Holothurians 

 of the genera Pkxaura and Plexatirdla.—Uv. Giinther, F.R.S., 



exhibited and .made remarks on some fishes which had been 

 dredged up by Mr. John Murray off the west coast of Scotlan(^^, 

 and were not previously known to occur in British waters, vidB 

 Cottus lilljebo7gii (Collett), Triglops murrayi, sp. n., Gadw^ 

 esmarckii (Nills.) Onus reinhardti (Collett), Fierasfer acus 

 (Briinn.), Scopelus scoticus, s^. n., And Stojttias ferox [KahxAt.). — 

 Dr. Giinther also exhibited and described a specimen of Lichia 

 vadigo (Risso), a species of which only a few specimens were 

 previously known from the Mediterranean and Madeira. This 

 specimen was obtained by Captain MacDonald on September 17, 

 1888, off Waternish Point, Isle of Skye. He also exhibited a 

 hybrid between the Roach [Leuciscus rutihis) and the Bleak 

 {Alburmis alburnus), sent to him by Lord Lilford from the River 

 Nun, Northamptonshire. — Mr. Beddard read a paper descriptive 

 of the coloured epidermic cell of y^olosoma tenebrarunt. — Mr. 

 Boulenger exhibited and made marks on a series of living 

 specimens of Tortoises of the genus Hotnopiis from Cape 

 Colony, lately received by the Society from the Rev. G. H. R. 

 Fisk, C.M.Z.S. 



Geological Society, February 6.— W. T. Blanford, F.R.S. , 

 President, in the chair. — The following communication was 

 read : — On the occurrence of Palseolithic flint implements in the 

 neighbourhood of Ightham, Kent, their distribution and probable 

 age, by Joseph Prestwich, F. R. S. The author stated that Mr. 

 Harrison, of Ightham, has discovered over 400 Paleolithic imple- 

 ments lying on the surface at various heights and over a wide 

 area around Ightham. A description of the physiography of the 

 district and of the distribution of the various gravels and drifts 

 was given, and in the absence of fossils, attention was called to 

 the different levels at which the deposits occurred, and to their 

 physical features and characters. Besides the river-gravels, two 

 groups of unclassed gravels were described, one occupying a low 

 level, and the other levels higher than that to which the river- 

 drifts reach ; the latter is of varied composition. In the case of 

 the Shode valley, only beds below the contour-level of 350 feet 

 in its upper part, and of 300 feet or less in its lower part, can be 

 referred to the former action of the Shode, and those above this 

 belong to a high-level drift of uncertain age. The composition 

 of the various gravels was described in detail. The implements 

 are found on the surface of the land at all levels up to 600 feet, 

 and Mr. Harrison has discovered them at forty localities in the 

 hydrographical basins of the Shode, the Darent, the Leybourne 

 stream, and in part of the Thames basin. Two groups of im- 

 plements extend far beyond the lim.its assigned to the river-drifts 

 formed since the present hydrographical basins were established, 

 and must be accounted for by some other means than those in 

 connection with the former regime of the existing streams. A 

 description of the general characters and variations observable in 

 the implements was given. It is evident from the condition of 

 most of the implements, that they have been embedded in some 

 matrix which has produced an external change of structure and 

 colour. In the case of the river-gravel sites, the question pre- 

 sents no difficulty. Three cases of implements have been found : 

 (i. ) where the flint still shows some of its original colour ; (ii. ) those 

 of which the surface has turned from black to white, has been 

 altered in structure, and acquired a bright patina, and which 

 show no trace of wear; (iii.) those of which the flint has also lost 

 its original colour, but has been stained, and is with or without 

 patina, — these are generally much rolled. The characters of the 

 first call for no comment. Those of (ii.) and (iii.) are very 

 marked, and there is no difficulty in referring each to a distinct 

 matrix. The implements of class ii. have been embedded in a 

 stiff brick-earth, generally of a reddish colour, and those of class 

 iii. seem to have lain in ferruginous beds of sand or gravel. 

 Reasons were given for supposing the surface to have been once 

 covered with a deposit of clay or loess, since denuded except 

 where preserved in pipes, and that a continuous plane descended 

 from the high range of the Lower Greensand to the Thames 

 Valley, which has since been lowered 300 feet or more. It was 

 also shown that the high-level deposits were formed anteriorly to 

 the post-glacial drifts of the Medway and Thames Valleys. It is 

 probable that the loess is a deposit from flood-waters, and that 

 some of it may be referred to the Medway flowing at a higher 

 level ; but the highest deposits cannot be so accounted for, and 

 the author referred to the possibility of glacial action, without 

 insisting on it. The deposit on the chalk-plateau is abruptly cut 

 off by the river-valleys, and the rudest forms of implements, such 

 as those of Ash and Bower Lane, occur on this plateau at from 

 500 to 550 feet, and the author thinks they may possibly be of 

 pre-glacial age. The changes which have taken place in the 



