Interlinguistics of interlinguistics are, however, not so constructive, but rather descriptive, comparative, historic, sociolinguistic, or concerned with translation by humans or machines. As for Esperanto, which is the most widely used constructed interlanguage, there is a relatively abundant literature about the language itself and its philology (see Esperantology). Only a few of the many constructed languages have been applied practically to any noteworthy extent. The most prosperous were Volapük (1879, Johann Martin Schleyer), Esperanto (1887 Ludwik Lejzer Zamenhof), Latino sine flexione (1903, Giuseppe Peano), Ido (1907, Louis Couturat), Occidental-Interlingue (1922, Edgar de Wahl) and Interlingua (1951, IALA and Alexander Gode), with
Mark Zamenhof usage of Polish national dresses. The police in the exploration suspected, that that anonymous letter was written by Zamenhof, because he led that time a concurs school for girls and already sooner had written various denunciation letters. Zamenhof indeed that time shared the possession of the school for Jewish girls. In 1866 in it were 63 pupils. Several Polish biographers write that Mark Zamenhof was teacher of the Bialystok high school (actual school). If he instructed in that high school, probably that was only for a short episode, that probably happened after the "January Uprising" (so in 1864). Prospective hire