Modern instruments and methods of calculation : a handbook of the Napier Tercentenary Exhibition (1914)
Horsburg, E. M. (Ellice Martin), Napier Tercentenary Exhibition (1914 : Edinburgh, Scotalnd) · London : G. Bell · leaf 126
Fig. 37.—Interference Guard, andCushioned Key-tops. … Fig. 38.—Macaroni Box. misoperated. Correction of the error is made by simply completing theunfinished stroke of the partially depressed key, after which the release keyis touched to unlock the machine. Another safety feature of the Controlled-Key is its automatic preventionof an incomplete…
