SOCIETY OF PHYSICS AND NATUP.AL HISTORY, OF C4ENEVA. 355 



I^eared, and we fmislied tlie twentietli volaaie in 1870. You liiive decided to 

 make a general index of this series, in order to facilitate researches 

 which will become every day more diflicult to exatniue in proportion as 

 the number of our volumes are increased. This index, which will ap- 

 pear at the same time as the present volume, has been i^repared by our 

 colleague, Alfred Le Fort, who very obligingly devoted his time and 

 labor to our interests. I am commissioned, in the name of the society, 

 to tender him our sincere acknowledgments. 



The recapitulation of the material contained in our first twenty vol- 

 umes has shown that it includes in all three hundred and fifteen notices 

 and memoirs, some of which constitute complete works. This iniblica- 

 tiou constitutes, therefore, an important collection, which can claim a 

 most honorable place among the scientific transactions of Europe. 



Lastly, I will add that, although at an expense somewhat exceeding 

 the means of the society, the rich herbarium, for vrhich our city is in- 

 debted to the generosity of the family of DeLessert, has been })laced in 

 the botanical conservatory prepared for that purpose, where it is now 

 definitely arranged in such a manner that botanists may have free ac- 

 cess to it. 



Before concluding this report, I desire, gentleiiK-n, to communicate a 

 circumstance which appears to me to have peculiar interest for us, as 

 it refers to the origin of our society. In a preceding report, one of 

 your presidents. Dr. Grosse, proposed at the fiftieth anniversary of 

 the first scientific congress held at Geneva to give you, with a talent 

 you all know how to appreciate, the history of the Society of Physics, 

 of which his father was oae of the founders. In some researches to 

 which I have devoted myself this winter, in order to find in the papers 

 of my family some documents relative to the history of this society 

 during the first years of its existence, I have found a piece which 

 appears to me worthy- of your regard. It is a letter of M. A. Pictet to 

 my grandfather, in which he announces the formation of the society and 

 incloses the names of its founders. I will give the most important part 

 of the letter : 



" I am commissioned, my very dear colleague, to offer to you, as likewise 

 to your son Theodore and M. Necker, membership of a society with which 

 I have the honor of being connected. I delayed mentioning it to you 

 until I could send at the same time the rules, a copy of which I received 

 yesterday. In reading them you will be informed of the obligations 

 imposed, which I hope will not frighten you. I have already attended 

 a meeting, and I assure you that, by the interest with which it- has 

 inspired me, I judge it will prove a favorable and useful project for 

 the i)rogress of natural science and the personal advantage of the in- 

 dividuals who comf)ose this society. 



" Below are the actual members : 



" M. M. Colladon, Tolfot, Gosse, Vauche, Jurine, Gaudy de Russie, 



