It originated between 1846-1849. In 1816 British signs were brought in, in 1846 Irish signs developed in the girls' school, in 1857 Irish signs brought into the boys' school. Related to French Sign Language. Several deaf schools with 750 to 800 students in each. There are informal male and female sign systems.
Females learn the male system during dating and marriage.
The informal system is referred to as 'Deaf Sign Language'. Irish Sign Language is a new unified system, a manual code for English. It has structural features such as directional verbs. It has influenced sign languages in South Africa and Australia. There is a committee on national sign language, and an organization for sign language teachers.