http://books.google.de/books?id=zSzn93fFgR0C&dq (Publisher version)
singhalese_alwis1852_o.pdf (Any fulltext), 26MB
Alwis, J. d. (1852). The Sidath Sangarawa: a grammar of the Singhalese language; transl. into English, with introd., notes and appendices. Colombo: Skeen.