Lines in etching are much more irregular, without being straight, unless they are essential to the picture. Engraving Unlike wood-cuts, additions could easily be made to plate simply by adding necessary detail. Alterations could be made by hammering the plate from the back, smoothing the surface and re-engraving. Steel 1820 to 1860. Used for all subjects.
Most early maps are copper engravings.
As the title suggests, the prints are comprised of dots. There were two ways that this was done. Generally, the method was a mixture of etching and engraving. The engraver covered the plate with a resin, as etching, and then dotted through the ground with a needle. Acid created the incisions in the plate.