2d. With 4° on 1 Inch above 25 Inches, i. e. on the 26th Inch.
3d. With 4° on .1, i. e. one Tenth of an Inch above 25 Inches: and lastly,
4th. With 4° on .19, Tenths above 25 Inches.
The practice.
359. 1st. In the first Table, with 4 Degrees on the left Hand vertical Column, and with 25 Inches, along the upper Range; at the Point of Meeting, is the Answer .0101[119] viz. the Expansion, or Rise of the Quicksilver standing at 25 Inches, and receiving an additional Heat of 4°: the Answer .0101 being the Expression for the ten thousand one hundredth Part of an Inch, (viz. in Height, by Expansion.)
360. Add this Number, .0101, Part of an Inch, or Rise by Expansion, to the Barometer resting at Inches 25, .19 Tenths, Units under Units, &c. thus: .0101.
361. 2d. Now, in order to obtain the Expansion with 4 Degrees, on .19 Tenths i. e. the nine hundred and tenth Part of an Inch of Quicksilver in the Tube (above 25 Inches,) it must be considered, where it ought to be found in the first Table.
Tenths of 1 Inch, above 25 Inches, it must be observed, are at some intermediate Point between 25 and 26 Inches; that is, above 25, yet not so high as 26, or more than 25, yet less than 26.
Therefore, to find the Expansion with 4 Degrees, on 1 Inch above 25, i. e. on the 26th Inch; look in the Table, first, with 4 Degrees on 25 Inches: then with 4 Degrees on 26 Inches. The respective Numbers are .0101 and .0105.
And by taking the Expansion with 4° on 25 Inches, from the Expansion, with 4° on 26 Inches, thus;