May 10, 1888] 



NA TURE 



35 



express complete volatilization, similar to -that observed in 

 the case of our sun. 



The question then arises, Are all the mixed fluting 

 stages really included among the objects already con- 

 sidered ? 



It will be remembered that in my former communica- 

 tion I adduced evidence to the effect that the mixed 

 fluting stage was preceded by others in which the swarms 

 were still more dispersed, and at a lower temperature. 

 The first condition gives us bright hydrogen ; the last 

 little continuous spectrum to be absorbed, so that the 

 spectrum is one with more bright lines than indications of 

 absorption ; and, in fact, the chief difference between the 

 spectra of these swarms and of those still sparser ones 

 which we call nebulae lies in the fact that there are a few 

 more bright metallic lines or remnants of flutings ; those 

 of magnesium, in the one case, being replaced by others 

 of manganese and iron. 



If my view be correct — if there are stages preceding 

 those recorded by Dune"r in which we get both dark and 

 bright flutings — it is among bodies with spectra very 

 similar to these that they should be found. 



The first stage exhibited in the objects observed by 

 Duner is marked by flutings 7, 3, and 2 (omitting the less 

 refrangible one not yet allocated), representing the flutings 

 Mg, Mn, and Fe visible at the lowest temperatures. 



The stars which I look upon as representing a prior 

 stage should have recorded in their spectra the flutings 

 7 and 3 (without 2), representing Mg and Mn. 



{To be continued) 



THREE DA YS ON THE SUMMIT OF 

 MONT BLANC. 



A LPINE men are already beginning to think of the 

 **■ work of the coming season. We commend to their 

 attention the following notes relating to the experiences 

 of M. Richard, who spent three days during the past 

 summer on the summit of Mont Blanc, with a view to 

 making a series of continuous meteorological and other 

 observations. There are many Alpine men who might, 

 if they pleased, follow his example without much incon- 

 venience to themselves and with considerable advantage 

 to science. The following is a summary of the record 

 which M. Richard has contributed to La Nature : — 



The summit of Mont Blanc is a station of the utmost 

 importance to meteorology, since it rises to a great 

 height (4810 metres), and overtops the whole Alpine 

 group. But it had not hitherto been considered possible 

 to remain there for any length of time. De Saussure, 

 whose statue is erected at Chamounix, passed some days 

 in 1788, on the Ge"ant hill, at the height of 3510 metres. 

 In 1844 Martin-, Bravais, and Le Pileur, pitched their 

 tent at the Grand-Plateau, 4000 metres high, and here 

 they passed several days, and made numerous and im- 

 portant observations. Hitherto no explorer had remained 

 on the summit of the mountain itself for any length of 

 time ; tourists making but a very short stay — usually only 

 a few minutes From these facts we can see the import- 

 ance of the scientific expedition carried out in the 

 summer of 1887, with great success, by M. Joseph Vallot, 

 one of the most daring and able members of the Alpine 

 Club. Having made, in 1886, a series of physiological 

 observations, during the ascent of some of the highest 

 peaks of the Alps, he determined to establish on Mont 

 Blanc three temporary meteorological observatories, the 

 first at Chamounix, 1050 metres high, the second on the 

 rocks of the Grands-Mulets, 3059 metres high, and ths 

 third on the summit of Mont Blanc. He constructed 

 meteorological sheds, and furnished each of them with 

 registering instruments constructed by MM. Richard 

 Brothers — a barometer, a thermometer, and a hygrometer. 

 The instruments placed at Chamounix and the Grands- 



Mulets were inspected every week, but those at the 

 summit could not be reached for fifteen days, on 

 account of bad weather. To superintend the lower 

 stations he procured the assistance of M. Henri 

 Vallot, a distinguished engineer, on whose competence 

 and carefulness he could rely. At Chamounix, M. 

 Joseph Vallot's plan was considered impracticable. 

 He executed it, however, in company with M. F. M. 

 Richard, one of the makers of the registers. No less 

 than twenty-four guides were necessary, on account of 



Fig. i. 



the great weight of the baggage (250 kilogrammes). At 

 midday, July 27, 1887, they began the ascent to the 

 Grands-Mulets. On account of the late start, the party, 

 overtaken by night, arrived at the Grands-Mulets at 10 

 o'clock. Getting to bed at 1 1 o'clock, the travellers set 

 out again the next morning at 3, after a light meal. 



M. Richard then proceeds to te'l the story of the jour- 

 ney and of the time spent on the top of Mont Blanc. 

 The ascent from the Grands-Mulets is difficult, but not 

 very dangerous when the snow is good. Crevasses have 



