Thanks to all who commented on my previous writing. It seems I should have
clarified the term pure SI. Before I do that, let me stress that SI a
coherent system. That makes it distinct from all previous, metric or
medieval or earlier systems. It is a dream come true to all who deal with
This would be a case of substitution (vs. conversion) where in new rational
metric size is used for the value of the measurement for the item being
converted. While conversion maintains the original standard value (rounded
appropriately for accuracy and precision), substitution defines a new
When Ireland converted from mph to km/h, they took the opportunity to review
all speed limits in the country. The actual conversion took place over one
weekend (See
http://www.independent.co.uk/life-style/motoring/features/ireland-goes-metric--fast-531570.html
for a new report).
From:
