Martin's writing machine for use by blind people, 1862.,The carriage of the machine is moved one space at a time when the printing lever is operated by the engagement of a pawl with a rack. On the carriage is mounted a circular disc with raised letters and perforated punches sliding vertically in recesses. The desired letter is moved into line with a pointer by the sense of touch, the operating lever is then raised and depresses a plunger which enters the appropriate hole at the opposite side of the disc to the selected letter. The plunger forces down the punch which makes a perforated letter in the paper. The paper is fed by rollers and a spring indent and ratchet and passes over a springy leather pad beneath the punch. It is reversed for reading, the shape of the letter being determined by touch on the rough edges of the perforations forming the letter shape.
Perfecting the Writing Machine: Blind and Visible Writing Typewriters - Science blog
Perfecting the Writing Machine: Blind and Visible Writing Typewriters - Science blog
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