i Guettard in Auvergne 35 



of comparatively small moment, but it proved to be 

 another important onward step made by the same inde- 

 fatigable and clear - sighted naturalist, and laid the 

 foundations of another department of the natural history 

 of the earth. It proved also to be the starting-point of 

 one of the great scientific controversies of the latter half 

 of the last, and the first decades of the present, century. 

 There is thus a peculiar interest in watching how the 

 discovery was made and worked out by the original 

 observer. 



The story goes back to the early months of 1752, for 

 on the 10th of May of that year Guettard read to the 

 Academy a " Memoir on Certain Mountains in France which 

 have once been Volcanoes." 1 He tells how he had under- 

 taken further journeys for the purpose of obtaining addi- 

 tional information towards the correction and amplification of 

 his map of France, showing the distribution of his " bands " 

 with their characteristic minerals. He was accompanied 

 by his former school-fellow and then his valued friend, 

 Malesherbes. On reaching Moulins on the Allier, he was 

 struck by the nature of the black stone employed for mile- 

 posts, and felt certain that it must be of volcanic origin. 

 On inquiring whence the material came, and learning 

 that it was brought from Yolvic, " Volvic ! " he exclaimed, 

 " Volcani Vicus ! " and at once determined to make with- 

 out delay for this probably volcanic centre. 2 His excitement 



1 M6m. Acad. Roy. Science, vol. for 1756, p. 27. 



2 Twenty-eight years after this discovery Guettard found himself forced 

 to defend his claim to be the discoverer of the old volcanoes of Central 

 France, and to ask his friend Malesherbes for his testimony to the justice 

 of that claim. Malesherbes accordingly wrote him a letter giving an 

 account of their journey to Auvergne, which Guettard printed in the pre- 

 face to his treatise, in two volumes, on the mineralogy of Dauphine. It 



