306 French and Prussian Royal Academies. 



not only of considerable advantage to science, but also a great 

 convenience to the observer. 



FRENCH ROYAL ACADEMY OF SCIENCES. 



The following prize subject has been announced by this Aca- 

 demy for competition during the years 182 1 and 1822 : 



*' To trace the gradual development of the aquatic Triton or 

 Salamander through its different degrees, from tile egg to the 

 perfect animal, and to describe the internal changes which it ex- 

 periences, but principally in regard to osteogony and the distri- 

 bution of the vessels." 



Prize — a gold medal of the value of 300 fr. to be adjudged in 

 the month of March 1822; essays to be sent in by the 1st of 

 January 1822. 



ROYAL ACADEMY OF SCIEiVCES OF BERLIN. 



The following question has been announced by this Society 

 for competition during the j'ear 1 822 : 



'^ Among the luminous circles which appear in the heavens 

 when the atmosphere is not entirely serene, the rainbow alone is 

 explained in a satisfactory manner, inasmuch as the phenomena 

 which it presents depend simply on the laws of refraction and 

 reflection of the light : but with respect to those luminous crowns 

 which we see frequently around stars, an explanation is wanted 

 more complete, and developed with more precision than any 

 which has been yet given. Not wishing to refer the pheno- 

 mena of crowns and parhelions to any thing else than reflexion 

 and refraction, and to discover in consequence the form, the po- 

 sition, and the interior structure, proper for the small corpuscula 

 supposed to exist in the atmosphere, the efforts of philosophers 

 have not been either very happy or very conformable to nature. 

 It is probably to other properties of the light that the pheno- 

 mena of these rings ought to be ascribed ; properties which 

 are subject to geometric laws, and may be manifested by philo- 

 sophical experiment. The recent researches upon light have 

 thrown so great clearness on several suspected or neglected theo- 

 ries, and have 5,0 advanced a knowledge of its modifications, that 

 it may be possible even to look upon the problem of the rings as 

 no longer unsusceptible of a new solution. However, the results 

 hitherto obtained appear incomplete and not sufficiently exact ; 

 and being as yet but slightly compared with the phenomena, it 

 is desirable to see a more delicate theory developed, and its agree- 

 ment with the truth better established by multiplied and circum- 

 stantial observations. The Society proposes therefore as a sub- 

 ject of prize — 



" To give such a mathematical and detailed explanation of 

 the luminous and coloured rings which are observed round 



the 



