"Definition of kilogram, amp, and kelvin set to change 'TIL NEXT TIME..."
Quote:
Originally Posted by
nhengineer
SNIP// I continually distracted myself by wondering how many times dose this make it that the metric system has been 'realigned' while
the Imperial system has remained unchanged since its standardization by the Anglo-Saxons in 1824.
Firstly: - It's unfortunately a common misconception that it has remained unchanged since 1824:
Reading tip: https://en.wikipedia.org/wiki/Intern...yard_and_pound
The last line of the top paragraph might suffice.
Secondly: Exactly how could you find a "realignment" to be detrimental to any system of units at all,
if it weren't for a belief in one system of units being "sacrosanct, eternal, natural or intuitive"?
-Given that: - How does the Imperial system itself (or your beliefs thereof) "suffer" from the Metric revisions above?
Personally: In being a "relativist", I don't personally believe in any "eternal truths or values" -
rather mere temporary, ad hoc assumptions, only to be used until proven false or something more operational turns up.
Hence, a realignment (within the system's consistency) is only yet another improvement for its utility.
Sort of a systematic "evolution" - (but then that concept will probably open yet another can of worms).
Thus my suggested realignment of the article's title above...
But then - all of the above is just one of my temporary working theories in using our crude human models
for putting some causality and predictability into an utterly incomprehensible and chaotic universe and its inhabitants.
"-Hello kids, today we explain why even BA threads are metric!"
Some further info on revisions to the Imperial systems since 1824:
not that any revision, per se, makes any system better or worse - but judge for yourself:
"Hence it was determined that the unit of length taken should be the ‘mil,’
and that the decimal system should be adopted for expressing dimensions."
These are the words of "the Small Screws Committee" (sic!) of the
British Association for the Advancement of Science in August 1882.
Info: 'mil' above meaning "thousandth of an inch" -
thus the use of "thou" and fractional measures is banned since August 1882.
Sources:
1st Report: https://www.sizes.com/library/technology/thread_BA1.htm
2nd Report: https://www.sizes.com/library/technology/thread_BA2.htm
Their take on "user friendliness" back then:
"the Committee alone is considering, not by any specific dimension, but by a number, which as a rule,
is arbitrarily chosen and does not of itself form a guide to the size of the screw." .
Thus the BA system has an angle of thread of 47,5 deg:
a #0 BA screw a diameter x pitch of 236 x 39,4 mil, ( M6 x 1 mm )
and a #20 BA only has a 19 x 4,7 mil, as each successive bigger # BA (but smaller) screw
has a pitch of 0.9 times the previous (lower # BA, but bigger screw).
Clear as mud?
Diameter explanation: "That the series of diameters for screws from 1/100th in. to ¼ in. be that given in millimetres in column V., the nearest thousandths of an inch being given in column II.; these diameters being the series calculated by making P, in the formula D = 6P6/5, having in succession the following values: 1 (or 0.90) mm.; 0.9¹ mm.; 0.9² mm.; 0.93 mm.; … 0.9n mm
Only two significant figures are taken to represent the diameters."
Pitch explanation:
"each pitch being 9/10ths of its predecessor, but that only two significant figures be used in their expression."