I was in a stationery store once when the customer in front of me asked for a 12-inch ruler. When the clerk handed it to him, the fellow asked, "Don't you have one longer?"

Now I'm no rocket scientist. Neither did anyone around me seem like Mensa material given the length of the lottery ticket line and the fact that the sign for the store was spelled STATIONARY. But this incident got me thinking. Maybe our system of weights and measures is a little confusing.

The metric system appears to be very ordered and logical. We Americans haven't been too quick to embrace it. Maybe it's a matter of stubbornness. Maybe it just feels unnatural to say:

Hey kids. No jackets today. It's 30 degrees out there.

Or what about:

The roast beef looks good, Joe. Give me 300 grams.

No, I guess we're happier with a system based on, what? A man's body?

We have a foot, a hand, a yard, a rod. . . What is a rod, anyway? It's 16.5 feet. Comes in handy all the time. So does a rood, which is 40 square rods. A pace is listed either as 30 inches or 60 inches, depending on what part of the stride you are trying to measure, an important distinction to be clear on probably only if you are planning to have a duel with pistols at dawn.

Here's something I always hoped I could use. When I went apple picking with the kids once, the much studied but hitherto unappreciated concept of bushels and pecks did come up, though at the time I forgot which was which.

A nautical mile is longer than a regular mile. A petroleum barrel holds more than a plain old barrel. And then there is that classic of confusion, 12 ounces in a pound but 16 ounces in a pint. Why not call it 14 ounces for both and be done with it? And that's without bringing up troy ounces. Where are they from, Helen of?

Then add to the mix the fact that some industries are all over the place with their own peculiar systems. Among other places, I've learned to not strain my brain at the lumberyard. A 2x4 will measure 1 ? x3 ?. But ? inch plywood will be ? inch thick. So 1 inch thick shelving pine will measure. . . you guessed it, ? inch thick. Apparently there are nominal sizes and actual sizes.

I guess that works with quantities too. There is what we want, nominally, when we go into the butcher or deli, and what we come out with, actually, which is more, the words "It's a little under" not being in a counterman's vocabulary.

I still think the guy with the ruler was a complete dope. But maybe he had his own set of logic. After all, there is a baker's dozen, 13 for the price of 12. And if so many things are "a little over," and sizes can be nominal and actual, and not a lot of it all makes sense, then why not try to get a bargain with a 12-inch ruler that's an inch or so longer? The worst that might happen is that he would eventually forget about the extra inch, and all his calculations would be totally screwed up.

Unless he were measuring lumber. Then maybe he'd be better off with a 13-inch ruler.