Advert for the American Letteries and Rubber Stores
Medium: Print on paper
This shop is advertising its range of "rubbers" or "letters", which were contraceptive devices worn by men during sex. Essentially, they were reusable condoms made from vulcanised rubber. The origin of this usage of the word "letter" is somewhat obscure; one of the more likely theories is that it is a form of inverted slang, in which the word "letter" is used to indicate "envelope".
A wide range of letters is advertised. The "French" letter derives its name from the nationality of the inventor of this type of contraception, a certain Dr Condom. The "Malthusian" letter takes its name from the Reverend Thomas Malthus, an economist who claimed in his celebrated 1798 essay 'On Population' that unchecked population growth always exceeds the growth of the means of subsistence (particularly food).
While the Victorian era was very nearly the first in which the working classes were actively encouraged to use contraception, thereby reducing the birth-rate and overcrowding in slums, family-planning remained an expensive and almost exclusively middle-class proposition into the 20th century.