Page 4 - Wind Waves and Weather

Petroleum Extension-The University of Texas at Austin
Units of Measurement

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hroughout the world, two systems of measurement domi-
Tnate: the English system and the met ric system. To day, the
United States is one of only a few countries that employs the En-
glish sys tem.
The English system uses the pound as the unit of weight, the
foot as the unit of length, and the gallon as the unit of capacity.
In the En glish system, for example, 1 foot equals 12 inches, 1 yard
equals 36 inches, and 1 mile equals 5,280 feet or 1,760 yards.
The metric system uses the gram as the unit of weight, the
metre as the unit of length, and the litre as the unit of capacity. In
the metric system, 1 me tre equals 10 decimetres, 100 centimetres,
or 1,000 milli metres. A kilometre equals 1,000 me tres. The metric
system, un like the English system, uses a base of 10; thus, it is easy
to convert from one unit to another. To convert from one unit to
an other in the English system, you must memorize or look up the
val ues.
In the late 1970s, the Eleventh General Conference on Weights
and Measures de scribed and adopted the Système International
(SI) d’U nités. Conference participants based the SI system on
the metric system and de signed it as an interna tional stan dard of
measurement.
The Rotary Drilling Series gives both English and SI units. And
because the SI sys tem employs the British spelling of many of the
terms, the book follows those spelling rules as well. The unit of
length, for ex ample, is metre, not me ter. (Note, however, that the
unit of weight is gram, not gramme.)
To aid U.S. readers in making and understanding the conver-
sion to the SI system, we in clude the following table.

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