Use of the GAUGE LINE. To find the content of any cylindrical vessel in ale gallons; seek the diameter of the vessel in inches, and just against it on the gauge line is the quantity of ale gallons contained in one inch deep: this multiplied by the length of the cylinder will give its content in ale gallons.
For example, suppose the length of the vessel 32.06, and the diameter of its base 25 inches; to find what
is the content in ale gallons? Right against 25 inches on the gauge line is one gallon and .745 of a gallon; which multiplied by 32.06, the length, gives 55.9447 gallons for the content of the vessel.
The bung diameter of a hoghead being 25 inches, the head diameter 22 inches, and the length 32.06 inches; to find the quantity of ale gallons contained in it?—Seek 25, the bung diameter, on the line of inches, and right against it on the gauge line you will find 1.745: take one-third of it which is .580, and set it down twice; seek 22 inches in the head diameter, and against it you will find on the gauge line 1.356; one-third of which added to twice .580 gives 1.606; which multiplied by the length 32.06, the product will be 51.60376, the content in ale gallons. Note, this operation supposes, that the aforesaid hoghead is in the figure of the middle frustum of a spheroid.
The use of the lines on the two other faces of the rod is very easy; you need only put it downright into the bung hole (if the vessel you desire to know the quantity of ale gallons contained therein be lying) to the opposite staves; and then where the surface of the liquor cuts any one of the lines appropriated to that vessel, will be the number of gallons contained in that vessel.