Linotype — The Line-Casting Machine

For four hundred years text was set the way Gutenberg had begun it: letter by letter by hand, and after printing every single letter returned by hand to its case. That returning — the distribution — often took longer than the setting itself.

Mergenthaler's machine distributes nothing. It melts it down. A keyboard drops brass matrices into a line, molten type metal is cast against them, and out comes a single solid bar of metal — a line o' type. The matrices travel back to the magazine automatically, and the bar is melted down again after printing.

US Patent 378,798, granted 28 February 1888, titled Machine for Producing Type-Bars. Mergenthaler came from Württemberg and was a trained watchmaker — which shows in the machine.