5C4 



NATURE 



\_March 25, 1880 



sphere. An examination of the rate of progress of storms in 

 north-western Europe, as compared with the rate in the interior 

 of the continent, would contribute important data to the inquiry 

 here raised. 



PHYSICAL NOTES 

 ACCORDING to a theory of crystallogenesis recently brought 

 before the Bologna Academy by Signor Marangoni, the forma- 

 tion of crystals is due to composition of molecular vibrations. 

 As vibrating plates give the symmetrical nodal lines of Chladni, 

 so solid bodies, in their vibrations in three directions, produce 

 nodal surfaces, which correspond to the cleavage surfaces of 

 crystals. The author (confining himself to simple substances) 

 considers a chemical molecule as one produced in general by 

 union of two atoms rotating round one another ; a physical, as 

 arising from two chemical rotating round one another. If these 

 motions do not occur in the same plane, we have motions of a 

 pendular nature in the three directions of space. Where the 

 times of vibration are in simple ratios to each other, crystals are 

 formed ; where, again, the relations are complicated or incom- 

 mensurable, we have liquids ; and in the gaseous state, the 

 physical molecules break up into the chemical. If the ratios of 

 the three motions are I : I : 2 we have 4 osculating planes, 

 enclosing a tetrahedron. The common orientation of these 

 planes in all molecules produces planes of cleavage. If the 

 ratios are 1:1:3, there are 6 osculating planes and a rhombo- 

 hedron. By means of a tuning-fork throwing a soap-bubble 

 into vibration, the author illustrates his hypothesis. He deduces 

 a number of crystallographic properties, further assuming that 

 parallel-directed vibrations attract each other, while opposite 

 repel. 



A series of experiments in spectrum-analytical comparison of 

 gas, sun, day, and the electric light has been lately made by 

 Herr Meyer (Carl's Zeilseli. fur angew. EUctr.-Lehre, 1. p. 320, 

 1879). lie used both Vierordt's method and a method first 

 suggested by Bonn ; in the latter a Nicol prism is fixed before 

 one-h.df of a slit and receives the light from one source; behind 

 it is the Nicol, rotatable in a graduated circle of Wild's polaristro- 

 bometer. The light beam passing through both prisms strikes a 

 rectangular glass prism, which reflects it into the spectrum 

 apparatus. The second slit-half is illuminated either directly or 

 through a second rectangular prism from the second light source. 

 The numbers show that the brightness of the colours in the gas- 

 spectrum, compared with that in sun or daylight and the electric 

 light, steadily decreases from the red to the violet end of the 

 spectrum. As sunlight is considerably brighter in the middle 

 parts of the spectrum than the electric light, the latter should 

 appear yellow with the former; and in a Ritchie photometer 

 the surface illuminated by the electric light did indeed appear 

 yellow like an orange, in comparison with that illuminated by the 

 sun. Another interesting fact elicited is that in daylight there is 

 comparatively more red and yellow, and less blue and violet light 

 than in sunlight. 



LAST year M. Van Rysselberghe devised a regulator rigorously 

 isochronous in theory, that is, the movable masses of which were 

 displaced exactly along a parabola. It was considered, however 

 (in the Belgian Academy), that practically the number of articula- 

 tions was too great to allow of the isochronism being realised. M. 

 Van Rysselberghe has now hit upon a different and very simple 

 combination, in which the articulations are reduced to a minimum, 

 and which gives a very close approximation to the parabola, 

 though not that figure rigorously. He has a model, the vel dry 

 of w hich is maintained constant to nearly nrW> while the force 

 transmitted to the vanes and absorbed by them, varies in the 

 ratio of 1 to 200. He does not despair of pushing the precision 

 t° tt. uWo (or less than a second a day). One special feature in 

 the apparatus is a system of vanes designed to increase the 

 resistance in a proportion slightly greater than that furnished by 

 the increasing aperture of the moderator-lozenge. These vanes, 

 on a straight horizontal axis, strike the air at different inclina- 

 tions according to the resistance to be developed, being moved 

 by suitable gearing, and automatically into various positions 

 from the horizontal to the vertical. There is also a system of 

 compensation for variations of temperature. This regulator is 

 expected to be of great service in application to registering at a 

 distance, to chromographs, to equatorial telescopes, to siderostats, 

 to telegraphs, and to industrial motors. (It is described in the 

 Bulletin of the Belgian Academy, No. 1, 1SS0.) 



Some experiments by Herr Reusch, with a view to determining 

 the modulus of elasticity of ice, have been recently published 

 {Ann. der Phys., No. 2). Rectangular prismatic lamella; of ice 

 were obtained by pressing the edges of two heated plates of 

 zinc, fixed parallel in a frame, into plates of ice, the ends being 

 then cut with two other zinc plates in the frame. After careful 

 measurement and weighing, the number of transverse vibrations 

 of the tone given by the lamella supported near the outer fifth 

 was determined by means of a Marloye sonometer (a monochord 

 I m. long, with tuning-fork giving 256 vibrations per second). 

 This was done, of course, in a room with the temperature below 

 zero. Calculating according to the formula given by Seebeck, 

 Herr Reusch found the arithmetic mean (from five experiments) 

 of the modulus of elasticity E, in kilogrammes per square milli- 

 metre = 236 - 324. The only previous determination known to 

 him is that of Frankenheim (in Mousson's "Physics"), where 

 E — 541, a number which -he therefore thinks more than twice 

 too great. 



In a recent paper in the Annalen der Pkyslk (No. 2), Herr 

 Frbhlich endeavours to prove that of the three electrodynamic 

 fundamental laws enunciated by Clausius, Riemann, and Weber 

 severally, as satisfying the principle of conservation of energy, 

 that of Clausius — and, supposing unequal velocity of the two 

 electricities in the galvanic current, the two others also — leads to 

 theoretically unreliable and practically useless results. 



GEOGRAPHICAL NOTES 

 Letters have been received from Prof. J. B. Balfour, 

 announcing that he had been safely landed by H.M.S. Seagull 

 in Golbourn Bay, at the west end of Socotra, on February 11, 

 weather not pei mitting the vessel to go round to the principal 

 port, Samarida. Prof. Balfour had formed pretty high expecta- 

 tions of the island from what he had heard, but these were 

 greatly exceeded by the reality. The flora was found to be rich 

 and varied, and 150 species of plants, some of great interest, 

 had been obtained in a few days. Birds were numerous, as also 

 reptiles and insects. There was plenty of water, and some 

 splendid Dytisci. The geology was very perplexing, granite, 

 limestone, and dioritic rocks being mixed up in an extraordinary 

 manner. 



We are glad to see that the Geographical Society is doing its 

 best to show honour to Prof. Nordenskjold and to give him a 

 hearty welcome to this country. A distinguished deputation- 

 awaited his arrival at Portsmouth on Monday, but unfortunately 

 the r<-;<7 did not appear, though by this time she has, most 

 ] irobably, arrived. The highest British mark of honour aw aits the 

 explorer — a dinner at Willis's Rooms, at which, we are glad to 

 learn, the Prince of Wales will be present. We have said so 

 much concerning the work of Trof. Nordenskjold that scarcely 

 anything new is left to say either concerning himself or con- 

 cerning his services to science in the voyage he has so 

 successfully accomplished. Commerce is sure to follow up the 

 pioneer w irk of the Vega, and we hope that very soon the 

 region explored will be garrisoned, as the Times puts it, by 

 meteorologists who will "watch the winds where they are born." 

 At the meeting of the Geographical Society on Monday 

 evening it was announced that Prof. Nordenskjold, who is 

 already a Gold Medallist, had been elected an Honorary Corre- 

 sponding Member. Mr. E. Hutchinson afterwards read a paper 

 on the ascent of the Binue branch of the Niger in 1879 by 

 Ashcroft, an agent of the Church Missionary Society, in 

 the little steamer Henry Venn. The party left Lokoja, at 

 the confluence with the main river, on July 8, and on Au- 

 gust 2S arrived opposite Vola in N. lat. 9 16' and E. long. 

 12° 31', some 364 miles to the eastward in a straight line. 

 From Yola they proceeded past the junction of the Faro tribu- 

 tary, where Dr. Barth crossed in 1S51, and for about forty 

 miles higher up, anchoring on September 4 off the town of 

 Garawa, which lies some distance from the river bank. This 

 place is situated in N. lat. 9° 28' 45" and E. long. 13° 26'. As 

 the river was falling fast, Mr. Ashcroft only ventured to go a 

 fen- miles further up in a steam launch. The distance traversed 

 by the Henry Venn Expedition, which had never been previously 

 explored, is probably not far short of 150 miles, and of this an 

 exceedingly good chart has been made by Mr. Flegel, a German 

 who, in his anxiety to join in the exploration, accompanied the 

 party as ship's clerk. It is satisfactory to learn that the natives, 

 except at one spot, showed themselves particularly well-disposed. 



