MacKinnon, c. 1879
Stylographic pens, often referred to as "stylos", have a writing tip consisting of a metal tube with a fine wire inside to regulate ink flow. Modern drafting pens are of similar construction, but have tips that are square-cut (for even line width) rather than rounded (for smoother writing). Stylos were the first mass-produced fountain pens to achieve broad market success; the inventor responsible was Duncan MacKinnon, a Canadian druggist. MacKinnon's "ink pencil" was patented in Canada and Britain in 1875 and in the United States in 1876. Not long after, A.T. Cross entered the market with a slightly modified version of MacKinnon's pen, dubbed a "stylograph".
MacKinnon, c. 1880
The rapid acceptance of nibbed fountain pens from the early 1880s on eventually eroded the stylographic pen's lead, but stylos remained a popular alternative all the way to the advent of the ballpoint. In the USA, one of the most prominent and long-lived stylo manufacturers was Inkograph, but many other firms offered stylos at some point or another.
Inkograph lever-filler, c. 1925
Inkograph lever-filler, c. 1948
Stylographic pens were widely popular, and were manufactured throughout the world. The UK was a particularly large producer through the first decades of the 20th century, with Mabie Todd probably the largest single maker. Winston Churchill reportedly used Conway Stewart stylos throughout the Second World War.
Conway Stewart "Universal", c. 1925
Montblanc 432 piston-filler, c. 1948
Stylos still tend to get short shrift from pen collectors, most of whom will pay more for nibbed pens even when their stylographic counterparts are much less common. While stylos do not offer the line variation and responsiveness of a flexible conventional nib, they still remain eminently practical writing instruments with a strong novelty element. Writing with a stylo is a bit like using a wet rollerball, with a bit more tooth but without any need to press down on the paper.