viz. 2165.13, the Expansion on the same 9000 Feet, viz. 21.87 with one Degree of Heat, and ——————— 2187.00 is the Answer by Addition. _Any vertical Number shewing the Expansion may_ likewise _be_ found, first, _by multiplying the first Figure, or Number, of the_ given _thousand Feet (in the horizontal Line,) into the Answer or Expansion on the_ first _thousand Feet, with one Degree of Heat: for Example_; To find the Expansion on 9000 Feet with one Degree of Heat. _The Expansion on 1000 Feet, with 1 Degree of Heat (from whence, all the other Expansions are derived) being 2.43; multiply that Number by 9, the first Figure of the given thousand Feet, and the Answer or Expansion with 1 Degree of Heat, is 21.87: hence all the Answers or Expansions_, immediately _under the horizontal Line of thousands, are_ formed. _Then 2dly, any other vertical Number or Expansion may be_ formed _by multiplying the Expansion_ immediately _under the_ given _thousand Feet in the horizontal Line, into the_ given _Number of Degrees: for Example_; To find the Expansion on 9000 Feet, with 50 Degrees. _The Expansion with one Degree on 9000, is 21.87: therefore the Expansion with 50°, is 50 Times more, viz. 1093.50, and so of the Rest._ _These different Methods serve to prove the Answers, and to elucidate the Table._ [125] _These Experiments were made with the Manòmeter when the Atmosphere was half an Inch heavier than in the Experiments to prove the Expansion of Quicksilver, the Barometer_ then _standing at 30 Inches only._ [126] There is _seldom_ Occasion to take more than the first Decimal out of the Table. [127] “RULE. “_Precept the 1st. With the Difference of the two Thermometers that give the Heat of the Barometer (and which for Distinction sake, are called the attached Thermometers) enter Table I, with the Degrees of Heat in the Column on the left Hand, and with the Height of the Barometer in Inches, in the horizontal Line at the Top; in the common Point of Meeting of the two Lines will be found the Correction for the Expansion of the Quicksilver by Heat, expressed in decimal Parts of an English Inch; which added to the coldest Barometer, or subtracted from the hottest, will give the Height of the two Barometers, such as would have obtained, had both Instruments been exposed to the same Temperature._