Ensign Model 97

Semi-automatic four-species calculating machine (ca. 1907)

The designer of the machine is Emory Seymour Ensign of Boston, USA, who was granted DRP 218541 "Calculating Machine" in 1907. The main claim of the patent is formulated as follows: "Calculating machine, in which a counter is moved one or more times in a circle past adjustable addition plates, depending on the value of a set multiplication switch plate, and is shifted laterally after each calculation, and the multiplier is made visible by a display device, characterized in that all addition and multiplication switch plates are shifted equally far and parallel to each other, and that all addition switch plates act in the same segment of the counter path, while the transfer from one place to another takes place in the following segment part of the path." The special feature of this machine, then, is the rotation of the result mechanism past the setting elements. The electric motor drives the main shaft and, via gears, the moving parts of the machine. The technical construction of the machine is visible on the cross section. Around 1900, after small electric motors had been developed, the motorization of the calculating machine began and, in connection with this, the automation of the calculating processes in office calculating machines. The first commercial four-species calculating machine with motor drive was probably the Ensign, after Alexander Rechnitzer's Autarith, which was built only in prototypes. It has a ten-key bank for the multipliers in addition to the full input keyboard; later this facility was called a "dial keyboard". In catalogs and advertisements, you can find the Ensign models 54, 75, and 97. The operation of the machine is extremely cumbersome, but as late as 1924, it was offered in two versions in stores. It has its own switching principle, for which no designation was introduced. The machine was not sold in Europe. It is extremely rare, only one other example is known to exist in the Russo Collection, USA.