The presence of these machines in the bank also had a tendency to influence business-men to install recorders where the key-driven calculator would have given far greater results in quantity of work and expense of operating. In these days, however, the average businessman is alive to his requirements, and selects what is best suited to his needs instead of being influenced by seeing a machine used by others for an entirely different purpose. The theory of using the printed list of items as a means of checking back has blown into a bubble and burst, and the non-lister has come into its own, not but what there has always been a good sale for these machines except for the first four years. [Sidenote: _Improvements slow for first few years_] On account of the years it took to educate business into the use of these two types of accounting machines, and the fact that the sales of both were small at first, there were few improvements for several years, as improvements depend upon prosperity. Such changes as have been made since were largely aimed at refinements, but there are some very noteworthy features added to the performance of both types of machines, which are explained and described in following chapters, where the subject will be treated under the class of machines they affect. [Illustration] [Illustration: The High-Speed Calculator] The High-Speed Calculator As previously stated, the calculating machine was old when Felt improved the Art by combining the key-drive with a plurality of co-operative orders of adding mechanism. The advantage in the machine he produced existed in the great increase in rapid manipulation which it offered over the older Art, especially in addition. To improve upon Felt’s contribution to the Art of calculating machines from a commercial standpoint demanded a combination that would give still greater possibilities in rapid manipulation. [Sidenote: _Felt improvements on Comptometer_] The patent records show that Felt again came to the front and gave to the public a new machine containing many new combinations of highly-organized mechanism that produced the above-named result. The patents showing these features are Nos. 762,520 and 762,521, the two patents being divisional patents of the same machine. Although there were several patents on key-driven calculators issued to others and a key-driven calculator placed on the market, which was sold to some extent, none of these calculators offered anything that would increase the possibility of more rapid manipulation than was to be had from Felt’s old Comptometer. [Sidenote: _Scientific distribution of functions_]