While on this subject it is noted that once the formula for the volume of a sphere was established it became only necessary to know the density of lead to mathamatically determine the sizes for any gauge. It is also noted that taking the volume of a sphere as Pi x D cube / 6 & lead @ 707.7 lbs per Cubeic foot /.40955 lbs per cubic inch; will not give the exact sizes given in the British proof charts. The difference is extremely slight, but is different.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra