\ 
Xll 
CONTENTS. 
XL VI II. An Inquiry info the Value of the ancier^ 
Greek and Roman Money : By Matthew Raper, 
Efq-, F. R, S’, p. 462 
XL IX. Defcription of a Method of mcafuring Differ- 
ences of Right Afeenfon and Decimation, with 
Dollond’s Micrometer, together with other ?iew Ap- 
plications oj the fame: By the Rev, Nevil Mafieelyns, 
B. D. F. R. S. Afro'.omtr Royal. p. 536 
L. A Supplement to a former Paper, concerning Diffi- 
culties in the Newtonian fheory of Light By the 
Rev. S. Horfley, LL. B. F. R. S. P* 547 
LI. An Account of the going of an Afronomical 
Clock: By the Rev. Francis Wolla(lon, F. 7 ^. .6^ 
LIl. An Account of d pure native crffallijcd 
Natron, or foffil alkaline Salt, which is jound in 
the Country of Tripoli in Barbary : By Donali 
Monro, M. D. Phyfeian to the Army, and to St. 
George’s Dofpital, Fellow of the Royal College of 
Pkyfcians, and of the Royal Society. . P- 5^7 
Llil. I he ^antity of the Suns Parallax, as deduced 
from the Obfervations oJ the Lranft of Venus, on 
June 3, 1769 : By Thomas Hornfby, M. A.. 
bavilian Profeffor oj AJlronorny in the Untverjuy of 
Oxford, and F. R. S. p. 574 
LIV. A Letter from Mr, R. E. Rafpe, F. R. S. to 
M. Maty, M'. D. Sec. R. S. containing a feort 
Account- of fome Bafait Hills Heiha. p. 580 
LV. An Attempt to explain fome of the principal 
P heenomena of Electricity, by Means of an elafic 
Fuiil: By the Honourable Henry Cavendhb, F. R, S. 
z p. 584. 
PRESEN 
