line

The line (abbreviated L or l or ‴ or lin.) was a small English unit of length, variously reckoned as , , , or of an inch. It was not included among the units authorized as the British Imperial system in 1824. Size The line was not recognized by any statute of the English Parliament but was usually understood as of a barleycorn, which itself was recognized by statute as of an inch. The line was eventually decimalized as of an inch, without recourse to barleycorns. The US button trade uses the same or a similar term but defined as one-fortieth of the US-customary inch (making a button-maker's line equal to 0.635 mm). In use Botanists formerly used the units (usually as inch) to measure the size of plant parts. Linnaeus's Philosophia botanica (1751) includes the Linea in its summary of units of measurements, defining it as "Linea una Mensurae parisinae"; Stearns gives its length as 2.25 mm. Even after metrication, British botanists continued to employ tools with gradations marked as linea (lines); the British line is approx. 2.1 mm and the Paris line approx. 2.3 mm.