> And to think, by now we could have metric clocks and metric calendars.
> Lets see, would a ten day week or ten day month be more "natural"?

How convenient not to notice that there was only one attempt at decimal
time/date calculations and it was aborted rapidly (after the French
Revolution). Nobody uses decimal dates but some use hexadecimal ;-). The
nautical miles are probably going to stay for a while, they are practical
(1naut.mile = 1second's worth of earth rotation at the equator - very
useful for navigation calculations - especially if you use a sextant).

The problem I see with the imperial system is there are too many
conversion constants and they are not consistent. On the way from
measuring a pcb drill to the area of your property there are enough
conversions to allow for rounding errors several times over imho, even if
you punch the right keys on the calculator every time. Not to mention for
the same on the distance from earth to mars.

Or the fact that a 3/16 drill is actually 0.1875 inches in diameter (wow,
that's accurate) but is specified to within +/-1/32 inches by this
notation (wow, that's inaccurate, it's anything between 0.21875 and
0.15625 inches diameter). That's an impressively accurate way to specify
imprecision (down to 50 nanometers - 1/32in = 0.03125in -> mm = 0.79375
exactly, which is 793.75 micrometers - and good luck with the rounding
errors if you need to multiply this a decent number of times and then
divide back in a DRO or CNC system that cannot do fractions, or, worse,
take a sine or cosine or log or two and then do the opposite operation on
a calculator with fixed precision). I admit that if you grew up
calculating with fractions it is probably natural to use them.

By contrast a metric drill will be specified to 4.8 mm which implies it is
between 4.75 and 4.85 mm diameter. And a propery would be say 30x20 meters
square which is 30,000x20,000 mm^2. Somehow I find this easier to work
with.

The metric constants are all very simple and easy to remember if you do
not need precision. Eg. 1 liter of H2O = 1kg. 1 hectare = 10^10 mm^2 (1ha
= 0.40468726 acre according to my conversion program).  Pressure at 10
meters depth in water is nominally 2at, at 20m 3at, etc, (pressure at sea
level is nominal 1at), 1 metric ton = 1000 kg = 1000000 grams = nominal
weight of 1000 liters of water, which nominally occupies a cubic volume of
1m^3 at stp (?) and so on and so on.

Peter

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