Slate and stylus
The slate and stylus are tools used by blind persons to write text that they can read without assistance. Invented by Charles Barbier as the tool for writing night writing, the slate and stylus allow for a quick, easy, convenient and constant method of making embossed printing for Braille character encoding. Prior methods of making raised printing for the blind required a movable type printing press.
The back of the slate is solid with slight depressions spaced in braille cells of six raised dots arranged in a grid of two dots horizontally by three dots vertically. In the shape of an inverted braille dot of approximately 1.5 mm (0.059 in) diameter; .75 mm (0.030 in) depth or height; the horizontal and vertical spacing between dot centers within a braille cell is approximately 2.5 mm (0.098 in) cell to cell (dot 1 center to dot 1 center horizontally) 6.5 mm (0.26 in).
The front of the slate has a corresponding rectangular cells with indentations in the side of the cell, over the depressions in the back so the blind user can properly position the stylus and press to form a dot.
There are pins or posts in the back of the slate positioned in non-cell areas to hold the paper in place and keep the top properly positioned over the back. The pins align with matching depressions on the opposite side of the slate. A slate as designed for a normal 8.5 inch piece of paper has 28 cells. It can have any number of rows, usually at least four.
The stylus is a short blunted awl with a handle to comfortably fit the hand of the user.
Writing is accomplished by placing a piece of heavy paper in the slate, aligning it correctly and closing the slate. The pins in the back of the slate puncture or pinch the paper securely between the two halves of the slate.
The person writing begins in the upper right, each combination of dots in the cell has to be completed backward. The awl is positioned and pressed to form a depression in the paper. The writer moves to one of the other dots in the cell or to the next cell as appropriate.
The slate is repositioned as needed to continue writing on the paper. When completed the writer removes the slate and turns the paper over to read the braille by feeling the dots that were pushed up from the back.
Prior to the system devised by Louis Braille, a number of other methods for blind people to read and/or write on paper were used. One of the most popular was the English system of Dr. William Moon invented in 1845. The English/Moon system or Moon type is easy to learn for the newly blind as it has a strong resemblance to the familiar written alphabet, but Braille has such great advantages over the Moon system for regular usage that it quickly eclipsed the Moon system. Braille with its slate and stylus was unique in that it was the first and, until computers with screen readers, the only method a blind person could write and read themselves what had been written.
The earliest systematic attempt to provide a method to "teach the blind to read and to write, and give them books printed by themselves" was by Valentin Haüy who used a system of embossed roman characters. In June 1784, Haüy sought his first pupil at the church of Saint-Germain-des-Prés. On 5 December 1786, Haüy's pupils had embossed from movable letterpress type his "Essai sur l'éducation des aveugles" (Essay on the Education of Blind Children) the first book ever published for the blind. Prior to 1786 tools for the blind to read or write were the results of individuals personal approaches to solutions. One of the more notable approach was that of Nicholas Saunderson (Lucasian Professor of Mathematics at Cambridge) blind nearly from birth, devised an Arithmetical slate.
Braille evolved from the night writing of Charles Barbier. "Ecriture Nocturne" (night writing) was invented in response to Napoleon's demand for a code that soldiers could use to communicate silently and without light at night. Because it used a cell with 2 columns of six dots each a total of 12 dots could be required for a single symbol, the cell was too large for a single touch and was hard to read and learn, it was not successful.
- Alpha Chi Omega (1908)
- Shrady, et al.(1902)
- Note: Different references assign invention of the slate and stylus to either Barbier or Braille. However, Braille (1829) credits Barbier with the invention. Barbier's slate consisted of six slots; Braille reduced it to three, as his cells were only half the size of Barbier's. When dashes were removed, the slots were no longer needed in full and were replaced with pairs of dots.
- Harry Houdini Collection (1888)
- ADA (1994)
- Note: The spacing for Braille dots and cells are NOT consistent throughout the world, See Braille Cell Dimensions at tiresias.org for a chart of different standards.
- Dodge (1920)
- "ENGLISH/MOON" (web). Duxbury Systems, Inc. September 2006. Retrieved 2008-04-01.
- Oregon Education Department (1897)
- Lowell, et al.(1893)
- "What is Braille?" (web). American Foundation for the Blind. Retrieved 2008-04-02.
- Alpha Chi Omega (1908). The Lyre of Alpha Chi Omega; Teaching the blind. Original from the New York Public Library: Alpha Chi Omega. pp. page 285.
- Dodge, Mary Mapes Dodge (1920). St. Nicholas; Chapter XI, the nine gifts. Original from the University of Michigan: Scribner & Co. pp. page 910.
- Perkins School for the Blind (1907). Report. Original from Harvard University: Perkins School for the Blind. pp. page 69.
- Shrady, et al.; George Frederick Shrady; Thomas Lathrop Stedman; Joseph Meredith Toner (1902). Medical Record. Original from Harvard University: W. Wood. pp. page 621.
- Harry Houdini Collection (1888). The Popular Science Monthly; Writing machines for the blind. Original from the New York Public Library: D. Appleton. pp. page 645.
- Oregon Education Department (1897). Biennial Report. Original from the New York Public Library: Oregon Education Department. pp. page 164.
- Lowell, et al.; Josephine (Shaw) Lowell, Fannie W. McLean, Mary B. Damon, Agnes L. Brennan, Blanche Wilder Bellamy, Jean Fine Spahr, Helen Moore, Elaine Goodale Eastman, Maud Wilder Goodwin, Julia Margaret Fuller Lloyd, Mrs Frederick Rhinelander Jones, Amelia Stone Quinton, Laura M. Doolittle (1893). The Literature of Philanthropy. Original from Harvard University: Harper & Brothers. pp. page 187.
- Wisconsin State Board of Control (1904). Biennial Report. Original from the University of Wisconsin - Madison: Wisconsin State Board of Control,. pp. page 222.
- Stadelman, Joseph M. (1913). "Valentin Haüy". Catholic Encyclopedia. New York: Robert Appleton Company.
- Sauvage, G.M. (1913). "Louis Braille". Catholic Encyclopedia. New York: Robert Appleton Company.
- ADA (1994). Americans with Disabilities Act: Accessibility Guidelines for Buildings. DIANE Publishing. pp. page 14. ISBN 0-7881-1830-7.