
Lots of blind people read the time, touching with the the tips of the fingers the face of hunters, which glass lid opens. The first timepieces for the blind were made up back in the 18th century (Tact Watch by Breguet).
In order to read the time with accuracy, some require just a gentle touch. But the majority of people face difficulties, defining the time this way, to say nothing of the increasing of the probability of error, as hour hands can be distorted or broken because of touching.
In order to solve this problem, an Austrian from Vienna introduced conventional symbols instead of the Roman numerals, the form of which allegorically looks like the figure of hours that they represent. The system of Lukaschovsky, having the name of its deviser, consists in representing one hour by a dot, two hours by two dots, three hours by a triangle, four hours by a square, five hours by a five-pointed star, six hours by a zero. In the first half of the dial, these signs are convex; in the second they are represented symmetrically but they are concave.
The hour hands are solid enough to resist frequent contacts of fingers, because they are made of steel.
Another system, thought up of by a watchmaker from Swiss, P. Tissot, has the advantage of using the Braille system, already known to the blind. The minute divisions are indicated by smaller prominent dots.