Raimey;
As you said a lot of those figures were too fuzzy to read for certain. On some that I could they seemed to be an exact metric conversion from the English tables. On those you put a ? after; 12/1 should be 18.8, 16/1 is 16.99/17.0, 16 = 16.81, & 17/1 16.64/65. These figures are derived from using the English numbers & converting. Those with double readings are dependant on exactly when rounding is done. Slight variations can of course occur on the exact diameter used for a 1 gauge ball. I found it necessary to carry this to 6 decimal places & then as a sorts middle of the road use 1.669285" as the basis. Using this number every size on the English tables fits to the nearest .001" which is good enough for me. I have tried them in metric but this number would convert to 42.399839mm.
It is noted that the volume of a ball this size is very slightly less than that given for 1 lb of pure lead. Perhaps when these tables originated well back into the 1800's a method of forming a pound of lead into a ball was used which gave it a slight compression. What is a bit amazing to me though is that even though all this had to be done by "Hand" & involves cubes & cube roots is that all these years later I can set down with a pocket calculator & fit it "Exactly" to that .001".
