Pratt’s US patent, issued in 1868, is titled Mechanical Typographer but he normally called his machine the Pterotype for unknown reasons. It wasn’t notably wingy.
Here’s how it looked in operation:
Each key had a long lever pivoted in the middle of the machine, and each lever activated three separate horizontal bars. All letters were on a single type-plate, formed by the stereotype process. Pratt’s patent mentions the ease of replacing this plate for different fonts, which Hammond turned into the most important feature. A Sholes-style machine with separate hammers couldn’t be switched out; you had to buy a whole new machine for a different font.
The nearest bar triggered the hammer; the next one pushed the type-plate from side to side via a bell-crank; and the back bar moved the type-plate up and down directly. Thus the X and Y axes of the keyboard became the X and Y axes of the typeplate, placing the chosen letter under the unchanging hammer. The key levers had setscrews adjusted to different heights, so each key moved the X and Y bars to its own position. This probably wouldn’t have worked well; the Hammond method of raising a pin and turning the type-plate until it hit the pin was far more definite.
While the type-plate was being pushed up and sideways, the hammer was being pulled back. At the bottom of the keystroke the hammer was released.
The paper was clamped to a two-way carriage. The outer carriage moved up and down to form lines, and the inner moved left and right to form columns. The big button on the right was the carriage return, which pushed the inner carriage back to initial position and slid the outer carriage up one row. (The paper was facing backwards, so the directions within one row were opposite to what you’d expect in a modern typewriter or printer.)
The patent mentions carbon-paper** between the hammer and paper as the ink source, so I haven’t tried to include a ribbon. Some of the available pictures seem to show a broad ribbon behind the paper.
Pratt’s keyboard was novel. Other early typewriters and telegraphs, including much later versions of Hammond, followed the piano model. Pratt set the trend for modern typewriters and computers.
There was no separate spacebar; you made a space by slightly pushing any key, which engaged the inner carriage escapement without triggering the hammer.
The carriage return was not copied by Sholes, and all Sholesian manual typewriters had a long lever on the carriage itself, which took your left hand away from the keyboard. The return key didn’t return until typewriters were electrified.
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** I think of carbon paper as secondary to typewriters, but carbon paper must have been common for duplicating handwritten documents long before typewriters.
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Continued in part 3, where I compare with Sholes and Hammond.
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Polistra's Mill 