line drawing

a drawing done exclusively in line, providing gradations in tone entirely through variations in width and density.

Origin of line drawing

First recorded in 1890–95

Political science research on redistricting has confirmed that control of the line-drawing process does yield some benefits.

Don't Overestimate Gerrymandering |Justin Green |February 18, 2013 |DAILY BEAST
It is somewhat difficult to exemplify this by a line-drawing, though it is easy to do so with an actual example.

Armour & Weapons |Charles John Ffoulkes
They reproduce, or almost reproduce, the color-charm of the early broadsides; and they show a marked improvement in line-drawing.

Exotics and Retrospectives |Lafcadio Hearn
Sometimes, though incorrectly, applied to a line-drawing in pen and ink.

The New Gresham Encyclopedia |Various

The one colour was used as a ground with the high lights cut away; the other block, for the ordinary convention of line-drawing.

English Illustration 'The Sixties': 1855-70 |Gleeson White

line drawing

a drawing made with lines only, gradations in tone being provided by the spacing and thickness of the lines