His own brother, Urbano Appendini, was made professor of mathematics. In 1808 Appendini published a grammar of the "Illyrian" language, written on the basis of the written Shtokavian literature and existing lexicographical works. In 1810 he wrote "" De Praestantia et Venustate Linguae Illyricae"" and another on the analogy between the languages of the ancient nations of Asia Minor and the languages of the Thracians and Illyrians. Both these are prefixed to the " Dictionary of the Illyric Language" of Father "Gioacchino Stulli" of Ragusa. He also undertook a work entitled " Il Varrone Illirico," on the etymology of the Illyric language, tending to show the derivation of the ancient names of the principal rivers, mountains, and other localities of Europe from Illyric radicals, but he did not live to complete the work. He also wrote biographies of noble men of Kotor (Cattaro).