the four-bank key board

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To make their models they hired one of Kleinsteuber's machinists, Matthias Schwalbach, who had got much of his experience as a blacksmith and tower-clock maker in Germany.7 So began the typewriter enterprise, in Kleinsteuber's shop.

7 Howard, in Typewriter Topics, 3:7. Densmore complained that not only were Sholes and Glidden ignorant of the " use of tools" but Schwalbach also, " though a man of good natural talent.of good ideas," was " bred a blacksmith," was " quite deficient in sight," and was a " very bungling coarse workman." James to Amos Densmore, Oct. 1, 1871. In this letter Soule was not mentioned, for he had left the enterprise before it was written, but apparently he had considerable mechanical skill.
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The inventor soon adopted a new keyboard, of Schwalbach's devising, which consisted of four rows of metal key levers and buttons set in ascending banks.18

18 Schwalbach afterwards said that " while he continued to work for Mr. Sholes for $3.00 a day, during the winter of 1870, he took up the work independently in his home." He "worked out the four-bank key board, and in the spring of 1871, he laid his completed model before Messrs. Sholes and Glidden." Howard, in Typewriter Topics, 3:8.
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He soon found that he must not only "superintend the making" but also direct a further redesigning of the machine. What was needed was to make it more durable .in particular, to design it so that the types would stay in line.

This was hard to do, because the short, stiff wires, which now directly connected key levers and type bars, pulled at an angle rather than straight. Four men.Sholes, Glidden, Schwalbach, and Densmore's inventive stepson Walter J. Barron.set to work on the problem. Glidden rigged up a system of intermediate levers to get a straight pull. Sholes disapproved, but Densmore encouraged Glidden to go ahead. Then, after spending two months and $1,000 on experiments, he discarded Glidden's scheme as too complicated, too " trappy." Meanwhile Barron suggested and Sholes and Schwalbach perfected an alternative method of pulling relatively straight. At the end of the summer of 1871 Densmore himself finally reached the conclusion that Sholes had first arrived at nearly four years earlier. Densmore said: "I think we are justified in saying that the invention is done, and the machine is now ready for the manufacturer."22

22 James to Emmett Densmore, June 18, 1871, and to Amos Densmore, Oct. 1, 1871.