May 26, 1892] 



NATURE 



95 



escapes from channels produced in those portions of it which are 

 in contact with the sides of the vessel. The central portion of 

 the magma therefore may be at a low temperature, whilst steam 

 at 100" is issuing from the sides.— Chemistry of the thioureas, 

 Part ii., by E. A. Werner. It is pointed out that the paper 

 recently published by Bertram on the monophenylthioureas was 

 evidently written in ignorance of the fact that the balk of the 

 work detailed therein has been already published by the author. 

 A number of new derivatives of thiourea are now described. 



Geological Society, May 11.— W. H. Hudleston, F.R.S., 

 President, in the chair. — The President announced that a bust 

 of the late Sir Charles Lyell had been kindly presented to the 

 Society by Mrs. Katherine Lyell, through the intermediary of 

 Prof. J. W. Judd, F. R.S. — The following communications were 

 read : — On the so-called gneiss of Carboniferous age at 

 Guttannen (Canton Berne, Switzerland), by Prof. T. G. Bonney, 

 F.R.S. It is stated by Dr. Heim {Quirterly Journal, vol. xlvi. 

 p. 237) that the stems of Calamites have been found at 

 Guttannen in a variety of gneiss, i.e. in one of a group of rocks 

 which exactly "resemble true crystalline schists in mode of 

 occurrence. Petrographically they are related to them by passage 

 rocks ; at least the line of separation is not easily distinguished, 

 . . . The Paiasozoic formations mostly show an intimate tectonic 

 relation to the crystalline schists, and have been converted 

 petrographically into crystalline schists." The Author describes 

 the result of a visit to the section at Guttannen in company with 

 Mr. J. Eccles (to whom he is greatly indebted for kind assist- 

 ance), and of his subsequent study of the specimens then 

 collected. The belt of sericitic "phyllites and gneisses," pre- 

 sumably of Carboniferous age, represented on the Swiss 

 geological map (Blatt xiii. ) as infolded, at and above Guttannen, 

 in true crystalline gneissoid rocks, is found on examination to 

 consist partly of true gneisses, partly of detrital rocks. The 

 boulder from which the stems in the Berne Museum were obtained 

 belongs to the latter. These rocks sometimes present macro- 

 scopically, and occasionally even microscopically, considerable 

 resemblance to true gneisses, but this proves on careful examina- 

 tion to be illusory. They are, like the Torridon Sandstone of 

 Scotland, or the Grii feldspathique of Normandy, composed of 

 the detritus of granitoid or gneissoid rock, which sometimes 

 forms a mosaic resembling the original rock, and which has 

 been generally more or less affected by subsequent pressure and 

 the usual secondary mineral changes. Thus, if the term be 

 employed in the ordinary sense, they are no more gneisses than 

 the rocks of Carboniferous age at Vemayaz (Canton Valais) are 

 mica-schists, but in some cases the imitation is unusually good, 

 and, so far as the author saw, there are at Guttannen neither 

 conglomerates nor slates to betray the imposition, as happens 

 at the other locality. The reading of this paper was followed 

 by a discussion, in which the President, Prof Judd, Mr. Eccles, 

 General McMahon, Mr. Rutley, Prof, Blake, Prof. Bonney, 

 and Prof. Seeley took part. — On the lithophyses in the obsidian 

 of the Rocche Rosse, Lipari, by Prof. Grenville A, J, Cole, and 

 Gerard W. Butler. The rock described in this paper differs in 

 no essential particular from that at Forgia Vecchia, or from the 

 obsidian on the north flank of Vulcano ; but the specimens show 

 in a specially striking manner the passage through various stages 

 of lithophysal structure, from indisputable steam-vesicles with 

 glassy walls to typical solid spherulites, A full description is 

 given of the formation of spherulites by a double process — firstly, 

 divergent growth from the margins of vesicles outwards, and 

 secondly, convergent growth inwards from the margins towards 

 the centres of the hollows, until in the smallest cases the fibres 

 from the opposite sides of the vesicle may meet in the centre, 

 producing a spherulite, which, but for the occurrence of inter- 

 mediate stages, might be supposed to have originated entirely by 

 divergent growth. The authors give details of the appearances 

 presented by intermediate stages of growth. The prevailing 

 type of spherulite, both in Lipari and Vulcano, shows in section 

 a dusky fibrous central area, which may possess concentric as 

 well as radial structure, surrounded by an irregular brown 

 cloudy zone of various width. The authors' studies lead them 

 to the conclusion that this type owes its characters to the dual 

 mode of growth, and therefore to the original presence of vesicles 

 in the rock. Commonly the process of infilling does not go so 

 far as this ; on the ends of the felspar fibres plates of tridymite 

 are deposited, and this seems to close the growth. It is clear 

 that the lithophysal structure of the Lipari obsidians was formed 

 during the cooling of the mass, and not by subsequent amyg- 

 daloidal infilling of vesicles. The authors discuss the effect of 



NO. II 78, VOL. 46] 



confined vapours on such rocks as those forming the subject of 

 the paper, noting that these vapours may be kept at a high 

 temperature for a considerable time, each vesicle thus becoming . 

 a sphere of hydrothermal action ; so that if the surrounding glass 

 remains at a temperature little below its fusion-point, crystalliza- 

 tion will be promoted in it, and at the same time the action of 

 the vapour in the vesicle will produce reactions on its walls. An 

 appendix, by Prof. Cole, treats of the lithophyses and hollow 

 spherulites of altered rocks. While admitting the presence of , 

 true lithophyses in many of the Welsh lavas, he is not prepared 

 to abandon a former suggestion that the interspaces between 

 successive coats of the Conway lithophyses result from alteration 

 of a formerly solid mass. In the lavas of Esgair-felen and near 

 the Wrekin he has no doubt as to the production of " hollow 

 spherulites" by ordinary processes of decay. The typical 

 Continental pyromerides are truly spherulilic, as is much of the 

 Wrekin lava. In the latter case and that of the rocks of Bouley 

 Bay it will be difficult to distinguish between infilled primary 

 and secondary cavities. In the discussion which followed the 

 reading of this paper Prof. Bonney, Prof. Judd, General 

 McMahon, Mr. J. W. Gregory, Mr. Rutley, Prof. Cole, and 

 Mr. G. W. Butler took part. 



Royal Meteorological Society, May 18.— Dr. C. Theodore 

 Williams, President, in the chair. — The following papers were 

 read : — Raindrops, by Mr. E. J. Lowe, F.R.S. The author 

 has made over 300 sketches of raindrops, and has gathered some 

 interesting facts respecting their variation in size, form, and 

 distribution. Sheets of slate in a book form, which could be 

 instantly closed, were employed ; these were ruled in inch 

 squares, and after exposure the drops were copied on sheets of 

 paper ruled like the slates. Some drops produce a wet circular 

 spot, whilst others, falling with greater force, have splashes 

 around the drops. The same sized drop varies considerably in 

 the amount of water it contains. The size of the drop ranges 

 from an almost invisible point to that of at least 2 inches in 

 diameter. Occasionally large drops fall that must be more or 

 less hollow, as they fail to wet the whole surface inclosed within 

 the drop. Besides the ordinary raindrops, the author exhibited 

 diagrams, showing the drops produced by a mist floating along 

 the ground, and also the manner in which snow-flakes, on 

 melting, wet the slates. — Results of a comparison of Richard's 

 anemo-cinemographe with the standard Beckley anemograph at 

 the Kew Observatory, by Mr. G. M. Whipple. This instrument 

 is a windmill vane anemometer, and is formed by six small 

 wings or vanes of aluminium, 4 inches in diameter, inclined at 

 45°, rivetted on very light steel arms, the diameter of which is 

 so calculated that the vane should make exactly one turn for a 

 metre of wind. Its running is always verified by means of a 

 whirling frame fitted up in an experimental room, where the air 

 is absolutely calm, and, if necessary, a table of corrections is 

 supplied. The recording part of the apparatus differs entirely 

 from any other anemometer, and is called the anemo- 

 cinemographe, and in principle is as follows : — The pen, re- 

 cording on a movable paper, is wound up at a constant rate by 

 means of a conical pendulum acting as a train of wheel links, 

 whilst a second train, driven by the fan, is always tending to 

 force it down to the lower edge of the paper ; its position, 

 therefore, is governed by the relative difference in the velocity 

 of the two trains of wheel-work, being at zero when the air i& 

 calm, but at other times it records the rate of the fan in metres 

 per second. The author has made a comparison of this instru- 

 ment with the standard anemometer at the Kew Observatory, 

 and finds that it gives exceedingly good results. — Levels of the 

 River Vaal at Kimberley, South Africa, with remarks on the rain- 

 fall of the watershed, by Mr. W. B. Tripp. Measurements of 

 the height of the River Vaal have for several years past been 

 made at the Kimberley Waterworks. These gaugings having 

 been placed at the disposal of the Society, the author has com- 

 pared them with the rainfall of the watershed. There is a 

 marked period of floods and fluctuations at a comparatively high 

 level from about the end of October to the latter part of April, 

 and a period of quiescence during which the river steadily falls, 

 with very slight fluctuations from about April 19 to October 31. 

 The highest flood (52-5 feet) occurred in 1880, the next highest 

 being 50*3 feet on January 24, 1891. 



Oxford. 

 University Junior Scientific Club, May 4.— The meet- 

 ing was held in the University Museum. In private, business 

 regulations about the '• Robert Boyle Lecture " were passed 



