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 of Zamenhof would be bound with the dismissal of many Polishes, that happened after 1863. Then Russian authorities sacked many Polish teachers. One reckons that in 1873 the Zamenhof family abandoned Bialystok. Even so unanswered is the question about the real cause of the transfer of Zamenhofs in Warsaw, where Mark surely advanced as a teacher of the German language in the Veterinary Institute and in the actual school, being that time only one from between three (!) Hebrews, that deserved to instruct in the Warsaw state schools . Because of what the local teacher received like this important position?