[coloradan]

Kindly tell me then, what is the SI unit of mass? (Since you’re the expert, and all.)

[Nathan Zachary]

Here's an interesting fact:

On April 5, 1893 the inch was redefined as precisely 1/39.37 meter, and in a very real sense we have been using the metric system ever since. In 1959 the length of the inch was shortened slightly to its present definition of 2.540 000 000 centimeters.