Parkinsonの用語選択というか 誤用？が 結構あとあとに影響？ keys..
Background on keyboard design
It turns out that this keyboard was designed experimentally by Christopher Sholes, the inventor of the typewriter, to slow the typist down. The keys on the early machines hung down in sort of a basket arrangement, and pivoted up to strike the platen (roller) from underneath. To see what you had typed, you had to lift up the roller so you could look at the paper. Since the keys had no springs on them, they fell back into place by gravity. This meant their action was very sluggish and if two keys that were close together in one quadrant of this ``basket'' were struck rapidly, one after another, they would jam.
The Dvorak Simplified Keyboard: Forty Years of Frustration, by Robert Parkinson, Missisauga, Ontario, From Computers and Automation magazine, November, 1972, pp. 18-25no title
の説明がつかない というか、 プラテン下面を叩くのは typebar だし、gravityで落ち戻るのもtypebar、、
key leverは spring back してたようなきがするし。
On the early machines