Naturalist's Almanac

National Metric Week occurs every October during the week that includes the 10th. So look for some discussion of the metric system every year about then.

The metric system, which is based on the meter and the number 10, has a 200-year history, but it’s still a relative newcomer to the world of measurement. Long before exact measurements became culturally important, human beings just used their body parts to approximate sizes and distances.

Native Americans, for instance, used their fingers, hands, forearms, and arms. The Greeks used their feet, and the Romans subdivided a foot into 12 units called unciae, from which the English word inches is derived.

When the Romans invaded northern Europe, they brought the 12-inch foot with them, and the northern Europeans added it to their own evolving yard. The yard was originally based on the size of a king’s waist, but King Henry I redefined it as the distance from the tip of his nose to the end of his outstretched thumb.

Later King Edward I defined the foot as one-third of a yard and the inch as one-thirty-sixth of a yard. And that’s the complicated British imperial system — which is actually based on the Romans’ attachment to the number 12 — that our ancestors brought with them to this continent. We still cling to this system as if it were our own invention.

The French were actually the inventive ones. After their revolution, the new leaders wanted a completely new system of measurement that would be based on scientific principles rather than Roman inches and British body parts. They came up with the metric system as a totally simple, internally consistent set of measurements based on the size of the earth.

The original meter was to be one ten-millionth of the distance between the North Pole and the equator — by way of Paris, of course. French astronomers spent six years measuring that distance and deriving the exact length of the standard meter. Other metric units were based on the meter divided by or multiplied by the number 10.

In 1790, Thomas Jefferson proposed that we adopt a similar system, but over 200 years later we’re still clinging to the old British imperial system that even the British have now abandoned. National Metric Week might indeed be a good time to reconsider the metric system. It seems to work for everybody except us.

MORE INFORMATION

Google Calculator
http://www.google.com/

One of the simplest ways to convert U. S. measurements to metric or metric to U. S. measurements is to type the conversion you want into the Google search box. For example, if you want to know how many centimeters there are in an inch, type 1 inch in centimeters into the search box, click on search, and the answer appears like magic: 1 inch = 2.54 centimeters. 1 meter in inches produces: 1 meter = 39.3700787 inches.

Conversion Tables
http://vulcan.wr.usgs.gov/Miscellaneous/ConversionTables/conversion_table.html

If you’d rather use math to do your conversions, this Cascades Volcano Observatory site offers a convenient table of all the formulas you’ll need.

Chronology
http://lamar.colostate.edu/~hillger/dates.htm

This U. S. Metric Association site offers a detailed chronology of the history of the metric system, starting in 1585 and ending with deadlines that will occur in 2009.

History
http://www.cftech.com/BrainBank/OTHERREFERENCE/WEIGHTSandMEASURES/MetricHistory.html

If you want to read a substantial history of measurement and how the metric system fits in, this long essay will provide you with lots of background information.