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Old May 3rd 04, 05:49 PM
Nicholas Fitzpatrick
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In article ,
Jay Windley wrote:

"Heinrich Zinndorf-Linker (zili@home)" wrote in message
...
|
| No, the problem with MANY (if not most) non-metric units is, that
| there are often several localized versions of them

Not when engineers use them. The English Engineering system is as rigidly
defined as the Systeme Internationale.


Hang on ... as an engineer, I have seen design errors made because someone
was sizing a pumping system in gallons per minute. And they used
Imperial gallons (4.55 litres) in the design, but they used
US Gallons (3.78 litres) when they installed the pumps. I've also seen
mindless conversion errors made, doing the simplest conversions
(feet to metres), causing elevation problems. And then there is the
problems I have seen with base-mapping, not knowing if the co-ordinate
system is set up in US Feet (0.3048 per metre) or US Survey feet
(0.304800609601 per metre), which the USGS seems to use differently
in diffent jurisdictions. And this might not seem much, but when
your State Plane co-ordinates are in the tens of millions (which they
often are), then you just created a 15-foot error in the location of
something, where your tolerance is less than a foot.

To keep things straight, we basically outlaw Imperial units on any
site, except those in the USA, where we outlaw metric units and only
use US units (though the US Feet versus US Survey feet remains an issue).
However, of late we've been seeing an interesting hybrid. Base-mapping
showing up in metric, however all the vertical elevations are still in
Imperial (boy, does that screw up a volume-calculation). I had a long
lecture from an engineer in one field office, when I queried his units
(which he hadn't labelled), to be told, that of course they were metric,
"Do you think we are hill-billies down here"? A week later, I learned
that although the horizontal was metric, the vertical was all measured
in Imperial ... which I guess I was supposed to assume ... oh well ...

Nick