Gabs vor Jaaaahren mal als Leserbrief in Nature :
Sir - As the owner of a hardware store, I feel it is my duty to comment on the letter from C.H.Evans (Nature 345, 658; 1990). The writer waxes sentimental about the British 'system' of weights and measures to which the United States alone so obdurately cling. Closer examination reveals that we don't have a system, we have a patchwork quilt of systems; systems whose units cannot be added, subtracted, multiplied or divided with ease, and hardly anyone knows how to use them. Learning a new system would come as a welcome relief to those who have actually learned the 'British system' and have to use it for complex operations.
The other day, a customer asked for a piece of lumber cut to "five feet two and a half inches and one of those little marks" (a sixteenth). What could be more elegant ? A carpenter more familiar with the system could translate that to more manageable sixty-two and nine-sixteenth inches. Of course if he has to add the width of a "one-by-twelve" (3/4" X 11 1/4") and deduct the thickness of a "two by four" (1 1/2" X 3 1/2"), he figures 62 9/16 + 11 1/4 - 1 1/2 = 72 5/16. In building a house (or a space shuttle), thousands of these tedious operations are carried out and each one is a potential source of error.
We start to see that within the 'system', things are not what they say they are. Two-by-fours are not 2 X 4 and they haven't been for years. The two-by-fours in a hundred-year-old house are 2 X 4, but the two-by-fours in a fifty-year-old house are 1 5/8 X 3 5/8, and in a new house they are 1 1/2 X 3 1/2. Half-inch galvanized pipe isn't half an inch anywhere.The inside diameter is about 5/8" and the outside diameter is about 13/16". Plumbers know what to ask for, but most others make the mistake of trying to measure the pipe and become hopelessly confused.
Electrical wire comes in gauges.As the wire gets bigger, the gauge number gets smaller. 12 ga. wire will conduct 4/3 as much current as 14 ga. 10 ga. wire conducts 3/2 as much current as 12. Crystal clear ! Nuts, bolts and screws also have gauges. Of course now as the bolt gets bigger, the gauge number gets bigger. What could be simpler than nails ? Nails are measured in pennies. The symbol is 'd' as in 'penny'. A 4d nail is 1 1/2" long, 6d is 2", 8d is 2 1/2", 10d is 3". So, it should be perfectly obvious that a 3 1/2" nail will be . . . that's right, 16d.
Drill bits cover all bases. There are of course fractional bits in increments of 1/64" where it is immediately obvious that 25/64 is larger than 3/8 but smaller than 13/32. Among the interstices between fractions there are number drills, an inverse system with no.1 a little smaller than 1/4" going "down" to no. 80 a little larger than a hair. Also interspersed between fractions are the letter drills irregularly spaced from A to Z with A a little larger than a no.1 going up to Z smaller than 1/2".
Concrete comes by the cubic yard, lumber by the board foot, shingles by the square, yarn by the skein, but the sack of cement is always 94 pounds. The tape in your walkman travels at 1 7/8 inches per second, which adds up to quite a few furlongs per fortnight. It's a Jim Dandy system all right, and any country that would give it up for something as straight as the metric has no sense of humour.
Ernest L. Asten
Cliff's Variety, 479 Castro Street, San Fransisco, California 94114, USA