158 Memoir upon living and fossil Elephants. 
had any appreciable influence upon the refractive power wher 
the sky is clear, and the air transparent. They propose to 
themselves further experiments upon this subject, and upon 
the refracting power of vapours; and as these experiments 
require high temperatures, they are obliged to wait for the 
great heats in summer. 
In order to reduce the gases to the same pressure and the 
same temperature in the calculation of the results, the au- 
thors made use of the Jaw laid down by Guy-Lussac, namely, . 
that by equal increases of heat there is the same law for all 
the gases, and that the dilatation of each is equal to 0°00375 
of its volume for each degree of the centigrade thermometer. 
This number was determined by 25 experiments, which did 
not sensibly differ from one another, and were made with 
tubes perfectly dry, and of exact calibres. ‘ This result,” 
the authors say, ‘as given by Guy-Lussac, is one of the 
most useful in physics ; it serves at the same time chemists, 
and even astronomers, to reduce their observations. It is 
probable that by adding the specific gravities of the gases 
and their refractive powers, as given in this memoir, an | 
exact and complete knowledge will be obtained of all the 
physical properties of a tiorae fluids.” 
We reserve for a future number the consequences deduced 
by the authors of the memoir from their experiments, and 
the development of the relations in which these results may 
be interesting to chemistry. 
{'To be continued.] 
XXVII. Memoir upon living and fossil Elephants. By 
G. Cuvier*. 
Tue fossil ossifications of elephants have excited not only 
the most lively interest in the minds of men of science, but 
also the curiosity of the vulgar in a high degree. Their 
enormous size has caused them to be collected and preserved 
wherever they were found; their frequency in every climate, 
* From Annales du Mustum d@’ Histoire Naturelle, année iv. cahier vii. p. 1. 
and 
