Old Units

This page presents a consistent system of measurements, traditionally used in England, the UnitedStates, and many other countries. Much of this system is the traditional English units from before the adoption of the imperial and metric systems. Many of these units are still commonly used in the UnitedStates. This page shows how the units are related to each other, and their practical applications.

As of 2003, these units are defined in terms of the metric system.

This page is not meant to become a flame war. Evangelical and disparaging comments are subject to deletion.

Distance units

There are:

1000 mils to the inch
12 lines to the inch
12 inches to the foot
3 feet to the yard
2 yards to the fathom
5.5 yards to the rod (a.k.a. pole or perch)
4 rods to the chain
10 chains to the furlong
8 furlongs to the mile (StatuteMile)
3 mile to the league

See CoolMeasurements for measuring with parts of the body.

Area units

There are:

4840 square yards to the acre (originally defined as being a chain by a furlong)
640 acres to the square mile (also called a section)
36 square miles to the township

Volume units

There are:

8 fluid dram to the fluid ounce
4 fluid ounces to the gill
8 gills to the quart
2 quarts to the pint
8 pints or 231 cubic inches to the (US) gallon
9 gallons to the firkin
42 gallons to the barrel
63 gallons to the hogshead

Weight units

There are:

16 dram to the ounce
16 ounces to the pound
14 pounds to the stone
2000 pounds to the short ton
2240 pounds or 160 stone to the long ton

The square mile is square, but the acre is not.

An acre is an area equal to one chain by ten chains, that's 22 yards by 220 yards. This definition came from the strip of land that used to be worked by one man, and it's long and thin because they packed into a field well.

Hence the square mile (1,760 yards x 1,760 yards) can be divided into 80 x 8 = 640 one-acre rectangles of 22 yards x 220 yards each. -- vk

A square mile, being 80 chains long on a side, divides nicely up into a grid that's 80 x 22 yards one way and 8 x 220 yards the other way, and 80 x 8 is very neatly 640 (acres).

Most of the UnitedStates was surveyed in 6 mile x 6 mile "townships". ( California's Spanish land grants being a notable exception.)

Q. Does this mean that 11 yards x 440 yards is not an acre?

A. The way the definition used to be phrased, you'd think not. The wording has been altered to reflect that. Consider a 2 acre plot for example? Can we be sure of it's shape? Is it twice as long or twice as wide? A statute of 1878 defined an acre as 4840 square yards, so now the acre is a definition of area regardless of shape. This ties in with present day use of the acre to quantify parcels of land whatever their shape.

The NauticalMile does not fit neatly into this system.

5400 NauticalMiles between the North Pole and the Equator.
1 NauticalMile is one arc minute on a GreatCircle?

Measuring nautical miles using the latitude scale at the side of the chart is very convenient. Measuring depth by fathoms (6 feet, approximately the spread of a man's arms) is very convenient.

The Imperial/US Customary system is a very sophisticated system, well suited for its purpose. That purpose being everyday use by people performing craft activities without special measuring equipment. It is pretty hopeless for automated scientific computation, but that's a relatively recent human activity. For almost all of its history the Imperial/Customary system was very flexible and effective.

A pound of most everyday materials is a couple of hands-full. It's easy to divide a pound into ounces (avoirdupois) by eye since there are a power of 2 ounces per pound (and drams per ounce, as it happens).

Yards, rods, chains and furlongs relate well to areas measured in acres. And so on.

Then again, the same relations are found in the MetricSystem, where a cubic meter equals a kiloliter and a liter of water equals a kilogram.

Compare to: WhimsicalUnitsOfMeasurement