The principal system of a few nations, the only
major industrial one being the United States. The
English system actually consists of two related systems-
the U.S Customary system, used in the United States
and dependencies, and the British imperial.
Britain, the originator of the latter system, is now
gradually converting to the Metric system.
of the units and the relationships between them are
generally the same in both systems, but the sizes
of the units differ, sometimes considerably.
unit of length is the yard (yd); the basic unit of
mass (weight) is the pound (lb). Within the English
units of measurement there are three different systems
of weights of which the most widely used is the avoirdupois.
The troy system (named for Troyes, France, where it
is said to have originated) is used only for precious
metals. Apothecaries’ weights are based on troy
weights; in addition to the pound, ounce and grain
which are equal to the troy units of the same name
– other units are the dram and the scruple.
For liquid measure, or liquid capacity, the basic
unit is the gallon.
The U.S gallon, or wine gallon
is 231 cubic inches, the British imperial gallon is
the volume of 10lb of pure water at 62°F and is equal
to 277.42 cu.in. The British Units of liquid capacity
are thus about 20% larger than to the corresponding
The U.S bushel, or Winchester bushel,
is 2150.42 cu.in and is about 3% smaller than the
British Imperial bushel of 2219.36 cu in.; a similar
difference exists between U.S and British subdivisions.
The barrel is a unit for measuring the capacity of
larger quantities and has various legal definitions
depending on the substances being measured, the most
common value being 105 dry quarts.