Extract from Sanger, 1921: 75.

The best “chop” is nearly always pictorial, supplemented in most cases by a few easily read Chinese characters. One of the very best chops is that used by the Japanese “Jintan” (see illustrations), which is advertised and used all over China. This chop consists of nothing but the head and shoulders of a man wearing a distinctive kind of hat, together with two simple Chinese characters that even the most illiterate coolie can read and remember (Sanger, 1921: 67).