CONTENTS. 
and alfo for its irregular Variation at the Time of 
an Aurora Borealis. By John Canton, M. A. 
and F. R. S. p. 398. 
XXXIX. A Better to the Right Honourable Hugh 
Earl e/'Marcbmont, F.R.S. concerning the Sec- 
tions of a Solid , hitherto not confdered by Geome- 
ters j from William Brakenridge, D. D. ReStor of 
St. Michael Baflifhaw London, and F , R. S. p.446. 
ERRATA. 
/»_ 96. in the Title to Art. XVII. for 1757, read 1758. 
P. 285. /. 4. from the bottom, after damaged, add, not. 
P. 394. /. 8. before late, infert the ; after of, dele the. 
I 
PH I- 
