Stephen Coles

“Bell Centennial’s bizarre “4” and “M” are a perfect lesson in type made specifically for its intended medium. In this case, the platform was telephone books. In 1974, AT&T asked Matthew Carter to replace their previous typeface, Bell Gothic, with something that could save costs by fitting more lines per page. To keep the type legible at tiny sizes on cheap paper, Carter made extensive use of a compensation technique called “ink trapping.” This reduces the amount of ink-spread that distorts letters by filling junctions and counters. So, what looks strange, even ugly, at large sizes, actually takes its proper form on the pulpy pages of a directory. Many capitalize on Bell Centennial’s curiosity to set eye-catching”
― Stephen Coles, The Anatomy of Type: A Graphic Guide to 100 Typefaces