548 Sir george shuckburgh’s Obfervations 
of an inch Englifh : and yet when I confider the number 
of his obfervations, and the unexampled diligence and 
care with which he made them, I am obliged to attribute 
the difference of our refults to fome other caufe than that 
of inaccuracy. If then future experience fhould demon- 
flrate, that the denfity of the atmofphere with a given 
heat is invariable, or nearly fo ; while the preffure of a 
whole column of it continues the fame, we may perhaps 
fearch for the caufe of our difagreement from hence, 
viz. the barometers of Mr. de luc were not fufficiently 
near each other in an horizontal direction: mine were 
feparated from two to three miles ; and his, I believe, at 
double or triple that diftance. It may be fufpeited, I am 
well aware, that the fyphon conftrudtion of Mr. de luc’s 
barometer might occafion this difference : let us fee whe- 
ther this be the cafe. Mr. de saussure (whofe inftru- 
ment was of Mr. de luc’s conftrudtion, and made, as I 
underffood, under his infpedtion) obferved at the top of 
the Mole, or at leafl nearly on the fame level with my. 
barometer, as follows : 
