132 THE HISTORY OF SCIENCE 



views are apparent, for he holds that veins are clefts 

 filled in from above by crystallization from aqueous 

 solution. 



Before Werner had begun his teaching career at 

 Freiberg, Desmarest, the French geologist, had made 

 a special study of the basalts of Auvergne. As a 

 mathematician he was able to make a trigonometrical 

 survey of that district, and constructed a map show- 

 ing the craters of volcanoes of different ages, the 

 streams of lava following the river courses, and the 

 relation of basalt to lava, scoria, ashes, and other 

 recognized products of volcanic action. In 1788 he 

 was made inspector-general of French manufactures, 

 later superintendent of the porcelain works at Sevres. 

 He lived to the age of ninety, and whenever Neptu- 

 nists would try to draw him into argument, the old 

 man would simply say, " Go and see." 



James Hutton (1726-1797), the illustrious Scotch 

 geologist, had something of the same aversion to 

 speculation that did not rest on evidence ; though he 

 was eminently a philosopher in the strictest sense of 

 the word, as his three quarto volumes on the Prin- 

 ciples of Knowledge bear witness. Hutton was well 

 trained at Edinburgh in the High School and Uni- 

 versity. In a lecture on logic an illustrative refer- 

 ence to aqua regia turned his mind to the study of 

 chemistry. He engaged in experiments, and ulti- 

 mately made a fortune by a process for the manufac- 

 ture of sal ammoniac from coal-soot. In the mean 

 time he studied medicine at Edinburgh, Paris, and 

 Leyden, and continued the pursuit of chemistry. 

 Then, having inherited land in Berwickshire, he 

 studied husbandry in Norfolk and took interest in the 



