28o Life of Defaiiffure. 



foot of Mont Blanc. Natural philofophers will read witli pleafure the defcription of liis 

 magnetometer. The more he obferred the mountains, the more he perceived the importance 

 of mineralogy. In order to ftudy it to greater advantage, he learned the German language; 

 and in the laft volumes of his Travels, we may eafify perceive how much new mineralogical 

 knowledge he had acquired. 



During his numerous excurfions among the Alps, and even in the midft of the political 

 troubles of Geneva in 1782, he found opportunities to make his experiments on hygrome- 

 try, which he publifhed in 1783 under the title of " An Effay on Hygrometry." This work, 

 the befl: he ever wrote, completed his reputation as a natural philofopher. We are in- 

 debted to him for the invention of an hygrometer. Deluc had already invented an hygrome- 

 ter of whalebone, on which fubjefl: a difpute was maintained between him and Defauffure, 

 which was even attended with a confiderable degree of earneftnefs. 



In 1786 Defauffure refigned the place of profeffor, which he had held for nearly 25 years, 

 to Pidet, his difciple and colleague, who performed with reputation to himfelf the difficult 

 tafk of fucceeding this great philofopher. 



Defauffure being called upon by his oiBce to attend to public education, made it a particu- 

 lar objedt of his attention. He prefented a plan for reforming the courfe of education at 

 Geneva. He propofed to teach children very early the natural faiences and mathematics ; 

 he was even attentive to their phyfical education ; and, that it might not be neglected, pro- 

 pofed the adoption of gymaftic excrcifes. This plan excited great attention in a town where 

 every one is aware of the importance of education. It found both admirers and cenfurers. 

 The mediocrity of their pecuniary refources was a great obftacle to every important innova- 

 tion. They were apprehenfive that in changing the form they might lofe fight of the 

 principle, and that an alteration, even for the better, might deilroy the good they poffeffed. 

 The Genevefe were attached to their form of education, and they had caufe, for it had not 

 only introduced general information among them, but had given the firft fpring to the talents 

 cf feveral diftinguifhed mathematicians *, and natural philofophers f. 



Public education did not alone claim the attention of Defauffure. He attended himfelf to 

 the education of his two fons and his daughter, who have (hown themfelves worthy of fuch 

 an inllrudor. His daughter unites to the accompIKhments of her fex, an extenfive know- 

 ledge in the natural fciences. His eldefl: fon is already known by his works in natural philo- 

 fophy a.nd chemiftry. 



The fecond volume of his Travels was publilhed in 1786. It contains a defcription of the 

 Alps which furround Mont Blanc. The author confiders them as a mineralogift, geolon-ift, 

 and natural philofopher. It contains, in particular, fomc very interefting experiments on 

 eleftricity, and a defcription of his eletSlrometer, which is one of the molt complete we pof- 

 fefs. We are likewife indebted to him for feveral inftruments of mcafurement ; his cyanome- 

 ter, defigned to meafure the intenfity of the blue of the heavens, which varies accordino- to 



» Abau7.ie, Cramer, I'Huiler, F. Trembley, &c. 



t JiiLibcrt, A. Trembley, Bonnet, Lefage, Dcluc, Senebicr, Prevoft, Pifttt, and DcfauITiire himfelf. 



its 



