572 Sir george shuckburgh’s Obfervations 
inftrument, which is now become nearly in as common 
polfeffion as a pocket watch, I have induftrioufly 
avoided the method of logarithms, propofed by Dr. h al- 
ley, and adopted by Mr. de luc, both becaufe fuch 
tables are not in the hands of every body, and becaufe I 
have perceived that many perfons of a philofophical 
turn, though dulled only in common arithmetic, have 
been frightened by the very name : a method lefs popu- 
lar, however elegant, would have been lefs generally 
ufeful. To thefe tables is fubjoined a lift of feveral alti- 
tudes, as determined by the barometer : this will ferve to 
fhew the ufe I have made of the inftrument, and will at 
the fame time exhibit the level of a great numbfer of 
places in France, Savoy, and Italy, and, as I think, be no 
improper fupplement to exemplify the rules. It might 
have been expected that I fhould have faid fomething on 
the theory of barometrical obfervations, and have laid 
down the laws and principles on which it depends ; but 
as that has been fo amply done by other writers of in- 
contefted authority, I fhall content myfelf with inferring 
only the following propofitions. 
i ft, The difference of elevation of two places may be 
determined by the weight of the vertical column of the 
atmofphere intercepted between them. 
3 
ad, If 
