The calculating machine of the Swiss clock-maker and precision-mechanic Viktor (or Victor) Schilt (1822-1880) was exhibited in 1851 at the Great exposition of the works of industry of all nations in Crystal Palace, London, and received an honorable mention and a bronze medal, placed after the calculating machines of Izrael Staffel and Thomas de Colmar.

The machine of Victor Schilt was a single column (only one-digit numbers may be entered) key-driven adder, almost an exact copy of the first calculating machine of Jean-Baptiste Schwilgué and there is an obvious reason for this resemblance—Schilt worked about two years in the workshop of Schwilgué in Strasbourg (around 1847-1848), before to return to his hometown (Grenchen, canton of Solothurn, Switzerland), where he later built many tower clocks.

In the workshop of Schwilgué in Strasbourg Schilt was mainly busy working on tower clocks, but undoubtedly he was engaged also in the making of calculating machines, because soon after leaving Strasbourg in 1848 he made the first example of his machine. At the 1851 London Exhibition Schilt reportedly received an order for the manufacturing of 100 machines (which seems an enormous amount for the time), but refused to produce them, probably because he wasn’t the inventor.

Now a copy of the Schilt’s machine, a solid and well-manufactured device, featuring the inscription *V. Schilt, Mechaniker in Solothurn*, is in the collection of the Smithsonian Institution in Washington (see the nearby photos).

Like other machines of this kind (so-called *single-column adders*), the device of Schilt was intended to add a single digit at a time, i.e. the unit column is entered first, then the tens, the hundreds, the thousands, and so on, certainly rather cumbersome task (as every partial sum had to be recorded on paper and the sum eventually performed), which greatly limits the usefulness of such devices.

It is a wood and metal device with measurements: 11.9 cm x 26 cm x 14.5 cm.

The front, top, and mechanism of the machine are steel, while the case is wooden. The plate and zeroing knobs on the top and the nine-digit keys across the front are made of brass. The machine adds numbers up to 299. Only one-digit numbers can be entered. The result is visible in a window on the plate.