Buttonmakers' Use
In the 9th century the term ligne came into use among German button makers, where it was used to measure the diameter of buttons. The consensus definition was that a ligne was the measurement of a round wick, folded flat. In this sense it measures 1⁄40 of an inch, but not exactly, for there were several inches in the kingdoms and petty states of Germany at that time. Such a measurement became the American measurement called "line," being one-fortieth of the US-customary inch. Its use was again to measure buttons, and was probably introduced by German immigrants.
The ligne system is in some instances still in use for buttons or snap buttons, where the size number of the button refers to ligne.
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