248 THE SCHOOL OF REAUMUR 



this mode of graduation has since been abandoned in 

 favour of a centesimal division. As the fixed points 

 adopted by E^aumur are still retained, all modern 

 thermometers are in a sense Reaumur thermometers ; 

 it must, however, be admitted that the original concep- 

 tion belongs to Newton. In the course of the numerous 

 experiments which this invention involved, Reaumur 

 made curious observations on the increase or diminution 

 of heat produced by the mixing of liquids, and also on 

 freezing mixtures. He collected with great care observa- 

 tions on the temperature of various places as registered 

 by his own thermometer, and gave an active impulse 

 to this branch of meteorology. He observed that a 

 freezing temperature does not prevent the evaporation 

 of snow. 



" In spite of the importance and practical utility of 

 the publications of which we have just given a very 

 brief account, there was yet more novelty and interest 

 in his natural history memoirs. Besides what he had 

 already written about the scales of fishes, the growth of 

 shells and petrified teeth, he described in 1710 the 

 modes of locomotion of many moUusks, star fishes, and 

 other invertebrate animals.^ In 1712 he made known 

 the singular phenomena relating to the reproduction of 

 cast limbs of crayfishes and lobsters. In 1715 he gave 

 a detailed account of the torpedo shock, and of the 

 organ by which it is produced, but electrical phenomena 

 were then too imperfectly understood to make a thorough 

 explanation possible. He examined several of our rivers, 

 whose sand contains gold, and wrote a memoir on them 

 in 1718. The vast layers of fossil shells, known in 

 Touraine as Faluns, did not escape his notice ; he 

 described them in 1720. He investigated in 1723 the 



*[The first descriptions of the ambulaoral feet was given bj' Reaumur.] 



