SOCIETY OF PHYSICS AND NATURAL HISTORY^, OF GENEVA. 345 



accidintal absence of our excellent colleague, ^I. E. Claparede, ahvays 

 vicli in conununications on other subjects of a character to interest the 

 society. Unfortunately the condition of his health this winter causes 

 us the greatest anxiety. 



General Dufour has given a summary of the results of the exper- 

 iments upon which he has been engaged for some time in regard to the 

 relative movement of material points, a question which is of interest to 

 general astronomy. 1. In studying the movement of tv»'o stars around 

 a supposed fixed point, it is demonstrated by observation that this i)oint 

 must be in motion. 2. The curve being plane, and the stars remain- 

 ing in the same plane during their translation, it mny therel'ore be con- 

 cluded that the stars have all received an impulse resulting in a parallel 

 movement. 3. The movement of the apsides proves that the center of 

 gravity of the system is displaced, not following a straight line, but de- 

 scribing a curved one. 



Professor Emile Plantamour has made this year, as formerly, a 

 sojourn among the mountaius, in order to determine the astronomical 

 coordinates of the different stations of Switzerland. The Simplon was 

 the place he selected for his operations in 1870. The latitude of this 

 station, as derived from his observations, is 40° 14' 59", 4, with a pos- 

 sible error of a quarter of a second. 



The unusually cold winter which we have experienced has naturally 

 attracted the attention of meteorologists, and M. Plantamour, according 

 to his custom, has given some results deduced from the compared course 

 of the temperature of diffe^-ent years. The months of December and 

 January of this winter have shown a mean temperature of 2°. 45. This 

 period of the winter is very similar to that of the winter of 18u7-'3S, of 

 which the mean temperature was — 2o.3; but the winter of 1829, 

 the remembrance of whicli is still traditional throughout the country, 

 was colder still, as in December and January, the mean temperature 

 was 40.7. 



Colonel E. Gautier has presented frequent communications rela- 

 tive to the constitution of the sun. In a i^aper read at the April 

 meeting he gave an account of an important memoir from Professor L. 

 Eespighi, director of the observatory of the capitol, upon some spectro- 

 scopical observations continued for fourteen months, and which have 

 been made principally with reference to the protuberances of the edges 

 of the sun. The author infers from his observations that the sun must 

 have an exterior liquid envelope, compressing the overheated gases 

 in its interior. These gases at times force themselves through the 

 envelope, and occasion formidable eruptions; after which they disperse 

 and combine with the elements of the surface of the sun. In consequence 

 of these combinations, obscure points appear which in agglomerating form 

 the spots on the disk of the sun. These masses Hoat at the surface of the 

 incandescent globe as dross a result arrived at by M. Gautier several 

 years ago in trying to re-establish the theory of Gallileo, and of Simon 



