• If your home is heated by gas that gas is measured by a gas meter.
• The electricity that runs your computer or charges your iPod arrives at the plug by first passing through an electrical meter.
• If you take a cab the price you pay is usually calculated according to the meter.

This word meter has been associated with measurement for so long that it actually shares its etymology with the word measure.

There are speedometers and pedometers and thermometers; all kinds of things that measure and use the word meter.

Getting really simple for a moment let’s think in one dimension.  One dimension is length.  The international standard unit of measure of length is the meter.

A couple of hundred years ago when the new revolutionary government of France chose to standardize units of measure, they chose the name for the most fundamental unit of measure from the oldest word root for measure we know of running back through Latin and Greek into Indo-European.

At the time there was a real need for standardization. Listen to this technique recommended by a handbook for surveyors.  When you need to measure something in rods the first thing you need to do is find out how long a rod is.  The way to do that is to stop the first 16 men who come out of church, whether they be tall or short, and get each one to place his foot end to end with his fellows.  The total length is your rod.

So I hope you’ll agree that a standardized unit of measure was worth while getting.  But looking back at how a standard meter was defined we can see that it wasn’t exactly straight-forward, one dimension or not.

Today a meter is defined very exactly as the distance that light travels in a vacuum in a fraction of a second.  The fraction of the second is something a very weeny bit larger than one three hundred millionth of a second.  Not easy to measure with a stopwatch; but very accurate when you can measure it.  That standard was established in 1983 because the old standard was seen as having the potential to change.  The old standard had only stood since 1960 and was based on a multiple of the wavelength of a certain specific color of orange light.  Again, a hard measure to mark out with a piece of string.  This 1960 standard had in turn taken over from a calculation of much longer standing.

The Paris Academy of Sciences back in 1790 decided that the only right and official way to measure a meter was to draw a line from the north pole right down through Paris to the equator and then divide that by ten million.  For almost 200 years that was the standard and in a temperature controlled vault in Paris there was a metal bar with that exact length marked on it—more or less.

To achieve this number the Paris Academy of Sciences was given a huge budget.  To get this budget the Paris Academy of Sciences was obliged to reject a standard for the meter that had already been accepted French National Assembly.  That standard was the length of a piece of string needed to make a pendulum that would swing with a period of one second.  Even though this was pretty nearly as accurate as the north pole to equator idea, it just wouldn’t get them their budget.  So funds were approved and a multi-year project begun.

The funny thing is that the business of France had to go on while these exacting measurements were made and to facilitate the business of France a provisional length of a meter was issued.   Then since everyone was using it, the provisional meter became the legal meter.

Since for most practical purposes the legal and provisional meters were close enough to whatever the exact meter was, when the exact meter was finally presented to the government it went into storage until people started worrying about the wavelength of orange light a few hundred years later.