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The Millionaire - Patent variations

Egli Name Plate (20kb) A comparison of the production machine, as described in the preceding sections, with Steiger's original patent descriptions shows the extensive contributions made by Engineer Hans W. Egli in preparing the design for commercial manufacture.

The illustrations below are extracts from US Patents 538710 and 558913. The full patents are available on-line from

Steiger's 1892 machine (26kb) Steiger's 1892 patent sets out the basic principles of his multiplying machine. The multiplication table, racks, cross-shafts, sliding differentials, and the tens-carry mechanism are all clearly described and illustrated. Three different constructions are shown to illustrate some of the manufacturing possibilities. In one version the multiplier body uses stepped discs rather than plates, assembled into a drum or barrel which is rotated into alignment with the racks. (Stepped or pinned barrels were established technology of the time, and were used as control elements in applications ranging from mechanical organs to Babbage's calculating engines). In another version, Steiger shows stepped plates attached to the ends of the racks, and actuated by a travelling comb which is lifted into alignment by the multiplier lever. Steiger obviously had a thorough understanding of the principles and the possibilities of his machine, but was undecided as to a suitable way to build it.

The 1895 application is concerned primarily with refining the details of one particular design which was to form the basis of the "Millionaire". Some of Steiger's details were used unchanged in the production machine, but a great many more were altered and improved by Hans W Egli as he prepared the design for commercial manufacture. Some of the more significant changes are described below.

Original text and images Copyright © John Wolff 2006-12.
Last Updated: 13 November 2012

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