Standard wire gauge and knitting needles

I went down to the library to join the knitting group. You can see my efforts at the top. Knitting needles are now measured in mm - their diameter. I am using 4mm needles. My micrometer screw gauge reads 4.01mm so the needles are accurately labelled! Older needles have a more archaic numbering system which means that the thinner the needle, the bigger the number. It turns out they used to be measured in standard wire gauge. A "28" needle, if it existed, would be as narrow as the copper wire pictured. My 4mm needles would be 8 in standard wire gauge. If you want the history of wire gauge, try this https://en.wikipedia.org/wiki/Wire_gauge. Basically, the number told you how many times the wire had been pulled through the machinery. Each pull made it thinner. Hence bigger number, thinner wire.