December 8, 1904] 



NATURE 



143 



is that a temporary star results from the collision of a dark 

 body with a nebula, the chances of such a collision being 

 much greater than the collision of two dark bodies. A 

 necessary consequence will be an intense superficial heating 

 with an atmospheric expansion in all directions. In what- 

 ever direction an observer may be situated, spectroscopic 

 observations will show, (i) a displacement violet-wards of 

 absorption lines or hands due to the absorptive action of 

 the expanding and cooling atmosphere advancing in the 

 direction of the observer with the hotter interior parts of 

 the star as background ; and (2) bright bands due to the 

 expanding atmosphere to right and left of the body of the 

 star, there being in this case no brighter background and 

 no spectral shift. Dr. Halm now imagines that the collision 

 is due to the advance of the dark body into a stream of 

 nebulous matter passing obliquely across the dark 

 body's path. This will at once give rise to a circulation 

 of parts of the nebula round the star, and these, of course, 

 will also be highly heated. The portions moving transverse 

 to the line of sight across the face of the star will produce 

 absorption bands in their normal position in the spectrum, 

 while the marginal portions moving on the one side towards 

 the observer and on the other side from him will produce 

 a shift of bright bands both towards the red and towards 

 the violet end of the spectrum. By compounding the effects 

 of these two conditions, namely, the simple expansion of 

 the atmosphere equally in all directions and the swirl of 

 incandescent matter due to oblique collision. Dr. Halm 

 showed that the two types of spectra obtained in the cases 

 of the recent Nova' were at once obtained. — Three papers by 

 Dr. Thomas Muir were also communicated, the titles being 

 " The Sum of the Signed Primary Minors of a Deter- 

 minant," "Continuants Resolved into Linear Factors," 

 and " The Three-line Determinants of a Si.x-bv-Three 

 .Array." 



November 21. — Lord M'Laren in the chair. — Mr. George 

 Romanes, C.E., read a paper on a possible explanation of 

 the formation of the moon. The general idea was that the 

 moon had grown to its present form and size by the gradual 

 agglomeration of what was originally a ring of satellites 

 broadly similar to what we know to exist in the case of 

 Saturn. On this hypothesis it was easily shown that the 

 process of agglomeration of a comparatively small body like 

 the moon could not be accompanied with an evolution of 

 heat sufficient to produce a molten globe, and that in con- 

 sequence the ordinary assumption of intense volcanic action 

 to explain the so-called craters was difficult to accept. But 

 it seemed possible to account for the rugged mountainous 

 surface of the moon with the " seas," ridges, " craters," 

 and peaks by means of the bombardment of those meteoric 

 masses, large and small, which in virtue of the combined 

 action of moon, earth, and sun were precipitated from time 

 to time upon the lunar surface. In the absence of an atmo- 

 sphere the masses so precipitated would impinge upon the 

 surface with high enough velocities to render the material 

 in the immediate vicinity liquid, the impinging mass also 

 itself being liquefied wholly or partially according to circum- 



[ stances. The author entered into a detailed examination 

 of some of the most striking features of the moon's surface, 

 and showed how this hypothesis accounted for them. He 

 also exhibited a mass of lead into which sinall bullets had 

 been shot at various incidences. The indentations repro- 

 duced the leading characteristics of the lunar " craters," 



' even to the small hill in the middle of the main depression. 

 It was also noticed that at the instant of impact the rim 

 of lead thrown up all round was made red hot. The 

 mysterious streaks so characteristic of Tycho in certain 

 aspects were explained as due to great splashes of material 

 which settled down in thin crystalline layers capable of 

 throwing off the reflected sunlight in definite directions. — 

 Prof. Coker described a laboratory apparatus for measuring 

 the lateral strains in tension and compression members. By 

 a well designed combination of levers and mirror attach- 

 ment an apparatus capable of being fixed to the bar itself 

 had been constructed, which was sufficiently rigid and yet 

 sensitive enough to measure a change of i/2o,oooth of an 

 inch. Some experiments on steel, iron, and brass bars 

 were described, in which the new apparatus was used in 

 conjunction with Ewing's extensometer, and values of 

 Poisson's ratio were given to three significant figures. The 

 values varied from one-third to one-fourth. 



NO. 1832, VOL. 71] 



Paris. 

 Academy of Sciences, November 28. — M. Mascart in the 

 chair. — On the possibility of chemical reactions : M. 

 de Forcrand. The author contends that the rigid appli- 

 cation of the thermodynamical condition of the possibility 

 of a chemical reaction is neither practical nor necessary, and 

 that the empirical rule that the disengagement of heat 

 settles the course of a reaction is the only possible experi- 

 mental criterion of the possibility of chemical reactions. — 

 On the prediction of chemical reactions : M. de Forcrand. 

 In general, accurate prediction of the course of a chemical 

 reaction is impossible, but there are two rules or principles, 

 one rigorous the other approximate. The latter, the prin- 

 ciple of maximum work, is a simplification of the first, and 

 ought to be considered as the only practical guide. — M. 

 Dastre was elected a member in the section of medicine and 

 surgery in the place of the late M. Marey. — The Leonids 

 in 1904 : Lucien Libert. Details of observations made at 

 Havre on the nights of November 14, 15, and 15, 16. in 

 meteors were observed and the trajectories measured. — On 

 the singularities of uniform analytical functions : D. 

 P6mpeiu. — On a new class of ions : G. Moureau. In 

 a previous paper it has been shown that a saline vapour 

 becomes conducting after passing through a porcelain tube 

 heated to about 1000° C, and remains conducting at much 

 lower temperatures, possessing the properties of an ionised 

 gas. In the present paper the mobilities of these new ions 

 have been measured. It was found that in the neighbour- 

 hood of the region of ionisation the mobilities of the vapours 

 are of the same order as the ions of the gases issuing from 

 a flame. — On the genesis of temporary radio-activity : Ed. 

 Sarasin, Th. Tommasina, and F. J. Micheli. The 

 authors conclude from the results of their work that a very 

 close relation appears to e.xist between ionisation and the 

 production of temporary radio-activity. The two pheno- 

 mena would appear to be reversible, the production of the 

 temporary radio-activity of a body being due to the absorp- 

 tion, or, perhaps, adsorption of an emanation which is 

 formed during the ionisation of a gas. On this view, the 

 radio-activity would consist in the loss by radiation of the 

 emanation adhering to radio-active bodies, this causing, in 

 its turn, the ionisation of a gas. — Stereoscopy without a 

 stereoscope : A. Berthier. The author points out that he 

 has already published a description of a method similar in 

 principle to that given by M. Ives in the Coinptes rendus 

 of October 24 last. — On the colloidal state of matter : G. E. 

 Malfltano. The author regards colloidal matter as a 

 system formed of an electrolyte dissociated into ions and 

 insoluble molecules grouped round these ions. — The influence 

 exerted by the removal of the moisture from the air supplied 



lo the blast furnace : A. Lodin. The results obtained by 

 Gailey at the Isabella blast furnaces, near Pittsburg, on 



he effect of drying the air forced into the furnace, have 

 attracted much attention in Europe, not unmixed with 

 scepticism. The author makes a comparison of the heat 

 balances in the two cases, and shows where the economy 

 IS effected. One indirect effect of the drying process is to 

 increase the temperature of the ingoing air, and a consider- 

 able portion of the economy effected may be attributed to 

 this cause. In Europe, where it is usual to work with the 

 air entering the tuyeres at a much higher temperature than 

 at the Isabella furnaces, the relative economy which would 

 be produced by drying the air would be too small to justify 

 the capital expenditure required to introduce the necessary 

 plant. — On the use of dry air in blast furnaces : Henri 

 Le Chatelicr. The economy claimed for the use of dry 

 air is ascribed by the inventor of the process to the fact that 

 the moisture of the undried air transforms a certain pro- 

 portion of the coke into hydrogen and o.xide of carbon. 

 From the figures of the amount of water removed it is 

 possible to calculate exactly this loss; it is 5 per cent., or 

 only one-fourth of the amount claimed. It is certain, then, 

 either that the economy claimed is incorrect, or else that 

 the true cause is to be sought for el'sewhere. The author 

 shows that the quality of the iron produced, especially as 

 regards its sulphur impurity, is an important factor, and 



that when the sulphur is to be kept down to a certain per- 

 centage the economy of fuel claimed by Gailey may be real. 

 — On wood spirit from Thuya articulata, Algeria : Emilien 

 Grimat. Carvacrol, thymohydroquinone, and thymo- 



quinone were isolated from the product of the distillation 



