JESPERSEN, (Jens) Otto (Harry) [1860–1943]. Danish linguist and authority on LANGUAGE TEACHING and the GRAMMAR of English. Born at Randers, Jutland, he was educated at Frederiksborg School, Zealand, and at the U. of Copenhagen, where he began to study law but changed to languages, taking a degree in FRENCH, English, and LATIN in 1887. During a postgraduate year (1887–8), he went to England, where he attended Henry SWEET's lectures on PHONETICS at Oxford and met James MURRAY and other scholars. He obtained a D.Phil. in Copenhagen in 1891, and in 1893 was appointed Professor of English, a position which he held until his retirement in 1925.

While still an undergraduate, Jespersen made contact with some of the leaders of the Reform Movement of language teaching; he translated Felix Franke's book about the Movement's principles into Danish (1884) and wrote in Danish a grammar of English using the then revolutionary method of giving phonetic transcription (1885). In 1901, he published a book on language teaching, Sprogundervisning (revised edition, 1935), translated into English as How to Teach a Foreign Language (1904).

When Paul Passy in 1886 in Paris formed the organization that later became the INTERNATIONAL PHONETIC ASSOCIATION, he was joined by Jespersen, who participated in the creation of the IPA system of notation. Jespersen later supplied phonetic transcriptions of the entries in Brynildsen's English and Dano-Norwegian Dictionary (1902–7), which was the century's first pronouncing dictionary. His main contribution to phonetics is a compendium originally published in Danish but issued in German in 1904, Lehrbuch der Phonetic, with its companion volume Phonetische Grundfragen. A book on the phonetics of Danish came in 1906 and one on the phonetics of English in 1912; the latter, originally written in Danish, was issued in an English translation in 1950.

Jespersen's publications on LINGUISTICS and grammatical theory are numerous, including: Language (1922); The Philosophy of Grammar (1924); Mankind, Nation and Individual (1925); Analytic Syntax (1937). His system of analysis of English grammar is explained in Essentials of English Grammar (1933) and A Modern Grammar on Historical Principles (7 volumes, 1909–49). Jespersen's theory has in part been superseded, but the mass of material that he collected and systematized retains its value. Volume I contains original views on the history of English sounds, including his account of the GREAT VOWEL SHIFT (Jespersen's own term). His views on the general development of English are set out in Growth and Structure of the English Language (1905).

Language teaching to Jespersen was a means of bringing nations closer together. With the same object in mind he became actively involved in efforts to develop an international auxiliary language. In 1907, he helped create a reformed Esperanto called Ido, and in 1928 developed his own auxiliary language Novial, in which he sought to apply a principle concerning simplicity in grammar and vocabulary which echoed the words of the English philosopher Jeremy Bentham: ‘That international language is best which in every point offers the greatest facility to the greatest number.’ Neither Ido nor Novial had any success. See METANALYSIS, SOCIETY FOR PURE ENGLISH, USAGE GUIDANCE AND CRITICISM.