[ 499 ] 
fide would be &' or 9'', and the fum of the contrary at- 
tradtions of Helwellin and Skidda would be 4'^; which 
quantities are not too fmall to be meafured and demon- 
ftrated by an accurate zenith fedtor, fuch as that belong- 
ing to the Royal Society, which I made ufe of at St. He- 
lena, would be, if the fault in the fufpenlion of the 
plumb-line, which I there difcovered, was corredled, 
in the manner fuggefted in the Philofophical Tranfac- 
tions, vol. LI V. p. 3.5 1 .. 
XLix, 
