4 HISTORY of the SOCIETT. 



1793- Lit. CI. Mr Stewart read the remainder of the Biographi- 



Eu.grai'.hic.i" cal Account of the late Adam Smith, LL. D. 



a^'coimt of \it 

 Smith. 



April ^. PI'}'/, a. Mr Playfair read feme Obfervations on Porifms, 



poriini?"""" additional to thofe formerly communicated. Thefe were in- 

 tended to prove, that the propofitions called Porifms do not, as 

 fome mathematicians have alleged, involve in them any viola- 

 tion of the law of continuity. This fubjedl belongs to the fecond 

 part of the paper, No. VII. of the preceding volume ; which fe- 

 cond part has not yet been fully communicated to the Society. 



MrFiiheron ^-j- j;]^;g meeting was alfo read a paper on Trigonometry, 



entitled, An Eafy and General Method for folving all the Cafes 

 of Plane and Spherical Triangles, by the Reverend Walter 

 Fisher, minifter at Cranlloun. 



It has long been an objedl with mathematicians to reduce the 

 rules of trigonometry to the fmalleft number poflible, and to 

 give them the form moft eafily retained in the memory. Lord 

 Napier, whofe difcoveries have fo much facilitated and abrid- 

 ged the labour of numerical calculation, applied himfelf to lim- 

 plify the rules of trigonometry with great fuccefs. He in- 

 vented the rule of the Circular Parts^ which gives an apparent 

 unity to theorems, where a real vinity is wanting, and is per- 

 haps the mofl fortunate attempt toward an artificial memory that 

 has been made by any of the moderns. 



Various improvements of this rule have fince been pro- 

 pofed. That of M. Pingre is one of the befl : He retains 

 Lord Napier's arrangement of the ciixular parts, and reduces 

 the rules of fpherical trigonometry to four ; the two firft of 

 which are Napier's, and the other two a generalization of the 

 common theorems refpedling the fegments, into which the 

 perpendicular, drawn to any fide of a fpherical triangle, di- 

 vides that fide, and alfo the angle from which it is drawn. See 



Mem. 



