

SCIENTIFIC NEWS. 



all thefe blank fpaces ; that is to fay, his tabic comprehends: 



the right afcenfion and declination of the middle of each of ^ 



thefe fpaces. 



The changeable ftars are comprehended in a fecond table ;, 

 they are thirty one in number. There are not more than 

 twelve, the periods of which are known ; but there are feveral 

 others which are diminimed fo as to difappear. By following 

 them attentively, we may determine the time which elapfes 

 between two fucceflive difappearances ; and this is a fpecies 

 of obfervation which Citizen Lalande propofesto the curiofity 

 of thole who, having only indifferent inftruments, wifhnever- 

 thelefs to be ufeful to agronomical fcience. 



A third table prefents thirty-three ftars of a red colour. 

 Since the year 1756, Mayer had remarked this colour in the 

 1 9th of Pifces, which he defignates in his regifters of obferva- 

 tions by the epithet of Rubicunda, as he finds by the copy, 

 which Prof. Lichtenberg has lent of all the obfervations made 

 by Mayer, on the day when he obferved Herfchel's planet. 

 Mitchell and Baillie fuppofe, that the colours of the ftars may 

 depend either on the different intenfity of their fire, or the 

 degree of their inflammation, and that the red colour may 

 indicate a fire which is in a diminifhing ftate. According to 

 this hypothecs, it would be a matter of importance to exa- 

 mine the changes of colour which take place in the ftars. Be 

 that as it may, thefe variations, if they exift, are certainly 

 extremely flow ; for the different fhades of colour which are 

 remarked at the prefent day in Antares, Ar&urus, Aldebaran, 

 Sirius, and the Lyre, exifted in the age of Ptolemy. 



Extra6i of a ?nemoir on the degree of magnet if m zvhich blades Coulomb on 

 offteel of different thick nefs acquire, and onfome refidts re/«//re masne ' m * 

 to the needles of the amipafs, by Citizen Coulomb.— Almoft 

 all the magnetic phenomena may be reduced to calculation, if 

 we fuppofe two magnetie fluids to exift in the fteel, in each 

 of which the molecules repel each other in the inverfe ratio 

 of the fquare of the diftances, and attract the particles of the 

 other fluid in the fame ratio. This law has been proved by 

 C. Coulomb in the Memoires of the Academy of Sciences for 

 1786, according to experiments which appear to be decifive. 



When the fteel is in its natural ftate, and has not been 

 touched with the load ftone, the two fluids are neutralized by 

 each other j that is to fay, they keep themfelves in equilibrio, 



and 



