 He could not speak Russian, and most of the representatives of the community suffered from the same disability, excepting a few merchants who cared little for the fate of the seminary; the older members were at a great disadvantage when pitted against the young students, who could gain whatever they desired from the authorities on account of their correct Russian accent.Benjacob corresponded with Jewish scholars in Western countries, and was known during his lifetime for his great achievements as a bibliographer, although his monumental work, the "Otzar ha-Sefarim, Thesaurus Librorum Hebræorum tam Impressorum quam Manuscriptorum," did not appear till seventeen years after his death (Vilnius, 1880).It was published by his son Jacob, and contains 17,000 entries of Hebrew printed and manuscript works, with valuable notes by M. Steinschneider.