28. Invention for the blind.
In the library of the Liverpool Athenæum is a book in French, printed for the use of the blind: the letters, which are very large, are raised cameo like, so as to be distinguished, it is supposed, by a practised touch. This is a very useless invention; whatever blind man could afford to purchase books printed in this manner, could afford to keep a person to read to him.
I have no where met with a more useful hint for the learned blind, than in the following passage from Thevenot's Travels.
"At Ispahan I saw one of those princes at his house whose eyes had been plucked out; he is a very learned man, especially in the mathematics, of which he has books always read to him: and as to astronomy and astrology, he has the calculations read unto him, and writes them very quickly with the point of his finger, having wax, which he prepares himself, like small twine less than ordinary packthread, and this wax he lays upon a large board or plank of wood, such as scholars make use of in some places that they may not spoil paper when they learn to design or write: and with this wax which he so applies he forms very true letters, and makes great calculations; then with his finger's end he casts up all that he has set down, performing multiplication, division, and all astronomical calculations, very exactly."