396 Intelligence and Miscellaneous Articles. 



It is to be presumed that among the smaller stars some other 

 spectrum will be found ; but for this purpose I think it is indispen- 

 sable to use a telescope with a greater power than that of nine inches, 

 or a more delicate eye. Nearly all red stars have spectra with 

 bands ; the small ones often present a continuous spectrum : this 

 continuity might be merely apparent, and these stars would belong 

 to the red type without bands, as is the case with Arcturus among the 

 large ones. In my researches I have not limited myself to the stars 

 of the catalogue, but each time I have traversed the surrounding 

 heavens ; thus I have discovered some new stars, but in small num- 

 ber, which leads me to believe that the greater number have been 

 noted, at any rate for our hemisphere. A similar study would have 

 to be undertaken for the southern hemisphere. 



Having at length been able to put up the complete apparatus for 

 the absolute measurement of the lines and their comparison with 

 chemical elements, I have confirmed that the rays of hydrogen coin- 

 cide with the four black lines of a Lyrae with surprising accuracy. 

 I say the four lines ; for even the most refrangible line of the violet 

 is found in its place in the spectrum of hydrogen. The tube with 

 which the observation was made was sent to me by M. Geissler of 

 Bonn, who prepared it with chemically pure hydrogen. The spec- 

 trum thus obtained agrees with that which has been given by *S1. 

 Morren of Marseilles. Another secondary line of lrydrogen appeared 

 in the spectrum of the star, like that of the yellow. After this it can 

 no longer be doubted that this substance forms the absorbing atmo- 

 sphere of this star, which was already known. But it is also evident 

 that the star a L)Tae has no appreciable motion of its own the velo- 

 city of which is comparable to that of light, as I have said in another 

 communication. The spectroscope used was made by M. Hoffmann 

 of Paris. It was formed of two very dispersive prisms ; and when it 

 was directed towards the sun, it separated the two lines of sodium 

 and the three lines of magnesium with great sharpness. 



The coincidence of the lines of hydrogen with those of the light of 

 the sun reflected by the moon presented the same degree of precision 

 and exactitude as for aLyrae. At the time of observation this star 

 was almost on the zenith. The observation w r as made on the 2nd 

 and 3rd of this month (August). It remains to be seen if, with this 

 delicate means, we do not succeed in ascertaining the influence of 

 the motion of the earth. I do not think it is impossible to appre- 

 ciate differences amounting to one-tenth the magnitude of the line /. 

 — Comptes Rendus, August 10, 186S. 



ON A THERMO-RHEOMETER. BY M. JAMIN. 



The instrument which I have the honour of submitting to the 

 Academy is a water-thermometer. The reservoir is a long glass 

 tube with a graduated stem which is bent downwards and termi- 

 nates in a cup in which water can be placed to fill the instrument. 

 The bottom of the reservoir is fastened in a mercury-cistern arranged 

 as in a Fortin's barometer. The mercury can thus be raised or lowered 

 by a measurable amount, which diminishes or increases the quantity 

 of w r ater in the reservoir ; and if its temperature be raised without 



