The first index typewriter to appear on the typewriter market was the Hall, in 1881 (patent date). The Hall was not only the first, but also one of the most successful index models. Production apparently continued until the end of the 19th Century.
The Hall was designed by Thomas Hall, a Brooklyn engineer. The first model, that was produced in New York, had a nickel-plated top shield. Later models were covered with blue steel.
Patent model for the escapement system of the Hall - 1878. (Clark collection)
The Hall was built into an oblong mahogany or walnut case. Before writing, the typist would place the machine upright at an angle (picture 4). The paper was fed from behind, under the platen to the front and again to the back, over a metal impression strip (picture 3)
Letters were selected from a square index card under a frame with holes (picture 5). While shifting the index pointer, a square rubber sheet holding the type was shifted into place to print the chosen character when the index pointer and the entire casing was pressed down.
This would also release a clamp at the top right of the casing so that the entire thing would move one space to the right. A space was made by pressing the casing down with the space button on the right. To free the escapement and move the casing back to the beginning of the line, one would compress the two levers at the top right. On all Hall models the spring was housed in a round brass wheel.