SCIENTIFIC NEWS* , 313 



Tt has long been remarked, that the observed velocity of Velocity «f 

 Sound is superior to what is deduced from algebraical cal- sound * 

 culations. It may be conceived, tha" the density and tem«? 

 perature of the air have some influence in this; but Mr, 

 Poisson demonstrates, that they are insufficient to explain 

 the observations. Having examined successively the causes 

 supposed by Newton and other geometricians, he finds 

 them incompatible with the results of sound, philosophy. 

 Mr. Laplace attributes the acceleration of sound to the 

 change of temperature experienced by the particles of air 

 in their condensation and dilatation, which cannot take 

 place without a successive evolution and absorption of heat. - 

 Calculation applied to this hypothesis, or rather incontes- 

 table fact, shows, from experiments made by the Academy 

 of Sciences in 1738, that a dilatation or condensation of ,^- T 

 produces a change of temperature equal to a degree of the 

 centesimal thermometer [1*8 Fah.]. 



The labours of the physical division of the class have 

 been analysed by Mr. Cuvier, perpetual secretary. 



In 1804 the class had awarded a prize to Doctors Her- »,., . - 

 holdt and Rafn, of Copenhagen, for a paper on the winter animals. 

 sleep of animals; and, in 1807, another to Dr. Saissy, of 

 Lyons. Prof, Prunelle, of Montpellier, has since sent a 

 paper, that may rank with the best on the subject. Still 

 however, notwithstanding their researches, and those of 

 Spallanzani, MangHi, and Carlisle, we are ignorant of the 

 causes, by which certain animals are 'disposed to this sleep, 

 and not o'thers ; as well as of th > e that enable them to en- 

 sure this suspension of thei.- fu icti< n . 



Mr. Geonroy-Saint-Hilaire, Prof, at the Museum of Na- Comparatiye 

 tural History, elected to s- c< e d *r-e ' te Mr. Broussonnet, 

 presented tothe class some fragments of a great work, which 

 he has undertaken on comparative osteology. His object 

 is to investigate more minutely the analogies between the 

 corresponding parts of various animals with vertebra?. In 

 fact those parts of organs, that are always found more or less 

 similar in number and position, notwithstanding their dif- 

 ference in size and use, and contradictorine^ to all apparent 

 final causes, must necessarily depend, on efficient and form- 

 ative causes. As these must be connected with the primary 



' means 



