Bill Hooper asked regarding my USMA 19842:
>I assume that R'3 is designated with the prime (') because it breaks the
>"rule" slightly to get the whole numbers. Done more strictly, the formula
>would give a ration of 2.154 giving the series:
>1, 2.154, 4.642, 10
>which might be rounded to:
>1, 2.2, 4.6, 10
>Am I correct, Joe, in assuming that this series is the one called R3
>(without the prime)?
>
>Rounding the above to the nearest whole number gives a series of whole
>numbers:
>1, 2, 5, 10
>The ratios for this series are:
>2/1 = 2
>5/2 = 2.5
>10/5 = 2
>which is not too far from the more rigourous, exactly constant ratio of
>2.154. But because it is not rigorously the R3 series, I'm guessing it is
>therefore designated as R'3.
>
>Regards, Bill Hooper
I confess. I invented the designation R'3. I could not find the 1 2 5
series in the ISO documents but this series is common, and I felt it should
be included in my table. The apostrophe indicates that it is a rounded
series. Perhaps monsieur Renard would deny paternity.
Joe
Joseph B.Reid
17 Glebe Road West
Toronto M5P 1C8 Tel. 416 486-6071
