Note 121 — An alphabetical index of the contents:
Reading edition
The Barometer, (to which the Scale of Heights is applied, in the 2d Column of the 2d Table) is supposed to be sunk within the Surface of the Earth, till the Quicksilver rests at 32 Inches, as appears from the last Article in the table, viz. 32 Inches, 0.00 Feet. 32 Inches is therefore the Foundation of the Table, and corresponds, according to Shuckburgh, to 1647 Feet, under the Surface of the Sea, at low Water.
This Depth then being the imaginary Level pointed out by the Quicksilver, at the unusual Extent of 32 Inches; each interior Inch and Tenth of Quicksilver will correspond to a superior Elevation of the Instrument, in Feet and Tenths above that Level, and will include the Mensuration of the deepest Mines.
For the mean Pressure of the Barometer, at low Water, from 132 Observations in Italy and England, is 30.04 Inches: the Temperature of the Barometer being at 55°, i. e. Temperate, and that of the Air at 62°.