58 Proceedings of Philosopfiical Societies. [Jan. 



with chalcedony ; the inferior part of these beds contains a very- 

 large quantity of petrified wood. Below the marl and chert is a 

 series of stratified rocks which the author calls claystone con- 

 glomerate ; they compose hills that are precipitous on one side, 

 and slope gradually on the other. In small specimens, the rock 

 resembles a clay porphyry, but it has not the usual relations of 

 this rock. It dips at a considerable angle to the north-west ; it 

 contains so much chlorite as to exhibit a green tinge ; this is 

 commonly thought to depend upon copper ; but the author attri- 

 butes it either to iron or manganese. The rock acquires a 

 conglomerate appearance from the numerous specimens of petri- 

 fied wood and fossils of all kinds which it contains. 



The woods are all tropical species, and generally of the palm 

 tribe. The most elevated paits of the island consist of rocks of 

 the newest floetz trap formation ; but the author conceives that 

 they are composed of a very large proportion of boulders included 

 in the conglomerate. 



A communication was read from Dr. Gmelin, of Tubingen, on 

 the subject of the clinkstone of Hohentwiel, upon which natrolite 

 is found. He informs us, that by heating it, he obtained from it 

 a quantity of ammonia ; and he found the same results from some 

 basalts which he tried. 



ROYAL ACADEMY OF SCIENCES AT PARIS. 



j4n Analysis of the Labours of the Royal Academy of Sciences 

 during the Year 1818. 



(^Continued from vol. xiv. p. 229.) 



An Historical Essay upon the Services and Scientific Works of 

 Gaspard Monge ; by M. C. Dupin, a pupil of Monge, and mem- 

 ber of the French Institute. — " G. Monge was born at Beaune 

 in 1746. His progress was such that they gave him the office of 

 Professor of Natural Philosophy in the college at Lyons although 



he had only begun to study it the year before Returning to 



Beaune in the vacation, he set about the survey of that town. 

 As he had not proper instruments for that purpose, he made 

 some himself. He dedicated his work to the administration of 

 his native place, and they recompensed the young author, as far 

 as the limited finances of the place would allow. A Lieutenant- 

 Colonel of the Engineers, who happened to be at Beaune, 

 obtained for Monge an appointment as draughtsman and pupil 

 in the Ecole d'Apparailleurs et de Conducteurs des Travaux des 

 Fortifications (equivalent to our Drawing School in the Tower). 

 As he was an excellent draughtsman, his manual dexterity was 

 alone considered. He, however, already knew his own strength, 

 and saw with great indignation the value that was exclusively 

 bestowed on his mechanical talents. ' I was tempted,' said he, 

 ' a longtime afterwards, a thousand times, to tear my drawings, 

 out of spite for the value set on them, just as if I had been good 



