1^4 Account of the Life and Wrttttigs 



At the end of fifteen months he returned to Upfjil, and i* 

 ^155 ^^^'^ ^ proof of the progrefs he had made in mathema- 

 tics and philofophy hy a difputation De Crepuf culls. Soon 

 after he tranfmitted to the Royal Academy of Stockholm two 

 dilTertations ; one of them, De Cocco AquaticOy and the other 

 De Hirudinibus; which were much approved by Linmcus^ 

 though he entertained an opinion on thefe fuhjec^s different 

 from that of the author. Ife defended alfo a difputation on 

 allronomical intercalation, in confequence of which he got 

 the degree of do6lor in 1758^ and by another difputation on 

 general xittra<Slion he obtained leave to become a private 

 teacher of philofophy^ Having improved himfelf in practical 

 aftronomy at the obfervatory of Upfal, he affilled in obferving 

 the tranfit of Venus in J 761, and was rewarded for his dili- 

 gence and application by being made affiftant profeiror of 

 mathematics and philofophy. 



He fent different papers to the Royal Academy of Stock- 

 holm ; one of which was on the rainbow, another on the 

 aurora horeaVtSy and a third on the twilight. The northern 

 lights and eleftricity attracted his particular attention, and 

 he at length laid before the Royal Society of Upfal a feries 

 of obfervations which he had made on tliefc fubjc6ls daring 

 the courfe of four years, together with a variety of informa- 

 tion collecled by learned men both in Sweden and in other 

 countries. His obfervations on electricity were fo much 

 approved, that an extract from them w^as inferted in the Phi- 

 lofophical Tranfa6lians by Dr. Wilfon. The fame work 

 contains his letters on the ele6lric nature of turmalin, which 

 nearly put an end to the difpute between Dr. Wilfon anet 

 JEpinus. 



In the year 1753 he obtained a prize from the Royal Aca- 

 demy of Stockholm for an anfwer to the queftion, How thofe 

 caterpillars which deftroy the leaves of fruit-trees can be ex- 

 tirpated ? and two years after a double prize for fome ne\v^ 

 obfervations on the fame fubjeft. He was fo zealous for the 

 interefl: of the Academy of Stockholm that he fent it forty-one 

 papers, each of which contained either fome new obfervations^ 

 or illultrated and expliyned what had been known before. 

 The Academy were fo fenfible of his fervices that in the 

 9 y^'^^ 



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