158 MEMOIR OF AUGUSTE BRAVAIS. 



mended by M. Be CaudoUe, and whicli comprises a matliematical for- 

 mnla for arriving' at the probable age of a fir-tree wliose diameter is 

 known. At Stockholm they carefully com[)ared their meteorological 

 iiistruuients, and iiarticularly their barometers, with those that were 

 ein[)Ioyed for (juotidian meteorological observations. This comparison 

 "was repeated in all the capitals and great cities through which they 

 passed in returning to France, and their instruments having been com- 

 X)ared before their departure, as they were at their return, with those of 

 the Observatory of Paris, a means was thus created of reducing to en- 

 tire harmony, and of referring in some sort to the same diapason, the me- 

 teorological observations which are prosecuted in a large part of Europe. 



Having returned to Paris in January 1840, they addressed to M. 

 A.rago a detailed letter on the labors of the Commission of the North, 

 which was inserted in the Comptes-Rendus of the Academy. Their eftbrts 

 were justly appreciated and well-earned rewards conferred on them, M. 

 Bravais receiving- on his part the decoration of the Legion of Honor, 

 and authority to wear that of the Swedish Order of the Sword. In his 

 capacity of marine officer he was charged by the minister witli the duty 

 of collecting, jointly with M. Lottin. all the observations on general 

 physics made by the commission, and superintending the i)ublication. 

 He was permitted at the same time to occupy a chair in one of the fac- 

 ulties of science, then lately created in different cities of France, and 

 was named professor of mathematics applied to astronomy in that of 

 Lyons, of which facultj" M. Tabereau, his future brotlier-in-law, the dis- 

 tinguished founder of the school of La Martiniere, was dean. Among 

 the observations niade by M. Bravais at the Observatory of Lyons 

 many would deserve to be cited, particularly one on a magnificent ap- 

 Xjearance of the zodiacal light in the month of February 1842. The re- 

 searches incident to a preparation for his new functions led also to the 

 composition of an important memoir on the movement of translation of 

 the sun, which he addressed to the Academy of Sciences, in 1843. From 

 the profounder theorems of mechanics on the mutual attractions of the 

 stars and the sun, he here establishes that the proper movement of our 

 total system is towards the star vj of the constellation Hercules. 



Elected, on his arrival, a member of the Academy of Lyons, JM. Bravais 

 bore, with his father and two of his brothers, a \Qxy active part in the 

 labors of the scientific congress assembled in that city, and laid before 

 it in detail various important considerations on the meteorology of the 

 south of France. He also contributed efficiently, with MM. Lortet and 

 Fouruet, to the establishment of the Hydrometric Society of Lyons, 

 widely known for its important and useful labors. With these occupa- 

 tions was united an assiduous co-operation in the production of a work 

 entitled Patria, which he edited during the three years of his residence 

 at Lyons, in conjunction with MM. Lalanne, Le Pileur, and Martins. 

 This work, undertaken with a view to utility, presents, in a condensed 

 and portable form, a miniature encyclopedia of everything relating to 

 France which it is most desirable to have for immediate reference. The 

 articles in this collection on geography, physics of the soil, as well as 

 many others compiled by M. Bravais, nnist always be regarded as models 

 of conciseness and lucidity. 



But Lyons is not remote from Switzerland and Savoy ; the sight of 

 the summits of the Alps, those old friends of his childhood, the sight of 

 the eternal snows, which recalled to him Spitzbergen and Lapland, easily 

 awakened in M. Bravais his instin(;ts as a traveler. In 1841, after the 

 close of his first course, he undertook a journey into Switzerland, and 

 in order to render it subservient to the continuation of his meteorologi- 



