576 "Froich Natianal Institute, 



the difference between the spherical and spheroidal angles is 

 not more than l-60th of a second in the greatest of our tri- 

 angles, and that the double curvature does not change the 

 length of the greatest of all our sides more than about a cen- 

 timetre. These results are confirmed by the ingenious ana- 

 lysis of M. Legendre. 



To these geometrical considerations upon the figure of 

 the earth, we were anxious to add the geographical re- 

 searches upon the e,\tensive plain of the interior of Africa, 

 by M. Lacepede ; the researches upon Persia, and the com- 

 munication of the Caspian with the Black Sea, by M. Oli- 

 vier ; but these memoirs belonging more particularly to the 

 physical sciences, and having been analysed by M, Cuvier, 

 Ave shall pass on to the New Memoir of M. Ramond upon 

 nu^asuring the Height of Mo7i7iiains hy the Barometer. 



We said in our notice of 1S05, that there was scarcely 

 )-500dth of difference between M. Laplace's coefficient for 

 calculating the height of mountains by the observation of 

 the barometer, and that which M. Ramond has deduced 

 from the numerous observations of this description which 

 he made in the Pyrenees. Some new researches have en- 

 tirely dispelled a difference which might be attributed to the 

 uncertainly either of the barometrical observations, or to the 

 old experiments upon the weight of the air and mercury, 

 which jM. Laplace considered as data in his calculation. 

 M. Biot has recently repeated these experiments with every 

 possible precaution : it results from this that the coefiicient 

 ought to be diminished by nearly l-300dth, and the agree- 

 ment between the two methods is then complete. On the 

 one hand, we see tiie geometrician resting on facts observed 

 in a cabinet, and deducing from thence a rule for measuring 

 the height of mountains : on the other hand, we see an ob- 

 r^erver taking for a base the known height of a mountain, 

 afid the effect it produces upon the elevation of the mercury 

 in the barometer, and concluding from it the relative weight 

 of mercury and air, and finding again the same quantity 

 which was made use of as the foundation of the geometri- 

 cian's calculations. These comparisons, which are daily 

 multiplving in the application of analysis j these identical 



results, 



