Dalgarno devised a communication system using
fingerspelling. He authored the book ''Didascalocophus or the Deaf and Dumb man's tutor'' (1680), which proposed a totally new linguistic system for use by
deaf mutes. Dalgarno was also interested in constructing what he called a '
philosophical language', now more usually referred to as
universal language. A modern translation of his
Ars signorum (
Art of Signs, 1661) was published in 2001 in an edition that also includes his autobiography and other manuscript writings. ==Notes==