Salih Zeki introduces Lobachevsky's geometry:
Two conferences in 1915

İnanç Akdenizci Demirtaş

Salih Zeki (1864-1921) a Turkish mathematician known for his extensive teaching of mathematics and the numerous textbooks he published in mathematical sciences for secondary and higher education. While he was acting as the director of the Istanbul Darülfünun (University), he delivered a series of conferences in the years 1914-1916 aiming to introduce non-Euclidian geometry.

The present paper aims to introduce two of his conferences titled "Lobaçevski Hendesesinin Tefsiri" (An interpretation of Lobachevsky's geometry) delivered on March 20th and 26th, 1915. Salih Zeki, became acquainted with non-Euclidian geometry thanks to another Turkish mathematician Vidinli Tevfik Pasha (1832-1901) who provided him with the material (books and articles) related to the subject.

In the first three conferences Salih Zeki exposed the theoretical grounds of Lobacevsky's geometry. In the following two conferences that are studied in the present paper, Salih Zeki showed the concordance of Beltrami's pseudospherical geometry with the plane geometry of Lobatchewsky, and that all results obtained by Lobachevky and Bolyai are also true for Beltrami's geometry.

Copies of Salih Zeki's conferences on non-Euclidian geometry during the academic year 1914-15 are kept in the Istanbul University Library. Although the Minister of Education approved Salih Zeki's plans to publish his conferences in the state printing agency, these were only partly published, and are conserved largely as manuscripts in the Istanbul University collection.

Key words: Salih Zeki, Darülfünun, non-Euclidian geometry, Lobatchewky, Vidinli Tevfik Paşa; Anahtar kelimeler: Salih Zeki, Darülfünun, Öklid dışı geometri, Lobaçevski, Vidinli Tevfik Paşa