Numb. 411. 
PHILOSOPHICAL 
TRANSACTIONS 
For the Months of October, November and 
December , 1731. 
The CONTENTS. 
I. A Propofal of a Method for finding the Longi- 
tude at Sea within a Degree , or twenty Leagues. 
<By Vr. Edmund Halley, Aiftr. Reg Vice - 
Trefident of the Royal Society. With an Ac- 
count of the Progrefs he hath made therein , by a 
continued Series of accurate Obfervations of the 
Moon, taken by himfelf at the Royal Obfer- 
vatory at Greenwich. 
II. An Account of the Contrayerva, by Mr. Wil- 
liam Houftoun, Surgeon in the Service of the 
Honourable South- Sea Company. 
III. A Letter from Jacob de Caftro Sarmiento, 
M. D. and F. <%. S. it, . 11 Morti- 
mer, M. T). Secr.P^S. concerning Diamonds 
lately found in Brazil. 
IV. Viri Celeberrimi Johannis Marchionis Po- 
leni, P(. S. S. ad Virum 'Doftijfimum Jaco- 
bum Jurinum, M. D. P(. S. S. Epiftola, 
qua continetur Summarium Obfervationum 
Mete- 
