CONTENTS. 
vn 
XXXIX. Chemical Experiments and Obfervations on Lead 
Ore. By Richard Watfon, D. D. F. R. S. in a Letter 
to Sir John Pringle, Bart. P. R. S. p. 863 
XL. Defcription of a mojl effectual Method of'fecuring 
Buildings againjl Fire , invented by Charles Lord 
ViJ 'count Mahon, F. R. S. p. 884 
XLI. A Method of finding, by the Help of Sir Ifaac New- 
ton’s binomial Theorem, a near Value of the very Jlowly- 
. . „ . XXX 3 X 4 X s , 
converging infinite Series a;+— + — + - + — + &:c .when 
x is very nearly equal to 1. By Francis Maferes, Ffq.- 
F. R. S. Curfitor Baron of the Exchequer. p. 895 
XLII. A Method of extending Cardan’s Rule for refolving 
one Cafe of a Cubick Equation of this Form, x z * - qx- 
~r, to the other Cafe of the fame Equation, which it 
is not naturally fitted to folve, and which is therefore of- 
ten called the irreducible Cafe. By Francis Maferes,. 
Efq. F. R. S. Curfitor Baron of the Exchequer, p. 902 
XLIII. Account of the Advantages of a newly-invented 
Machine much varied in its Effects, and very ufefui 
for determining the perfect Proportion between different 
Moveables acting by Levers and Wheel and Pinion.- 
By Mr. Le Cerf, Watch-maker at Geneva; Commu- 
nicated by Lord ViJ, count Mahon, F. R. S. p. 950 
XLIV. New Experiments upon the Leyden Phial, refpect- 
ing the Termination of Conductors. By Benjamin 
Wilfon, Efq. F. R. S. p. 999 
XLV. Obfervations on the Solar Eclipfe which happened 
June 24, 1778. By Mr. William Wales, F. R. S. and 
Mafler of the Royal Mathematical School in Chrift’s 
Hofpital,. p. 1013 
XLVL. 
