Joseph Edmondson's circular calculating machine
The englishman Joseph Edmondson had begun making calculating machines in Halifax, Great Britain, later the business moved to Norwich. In 1883 he received three Great Britain patents for a circular calculating machine, based on the stepped-drums mechanism (patents No GB188316, GB18830016 and GB188300016). The machine was manufactured for some time in Halifax, by the company Blakey, Emmott & Co, a producer of telephones, but it is unknown how many devices were manufactured. The machine was described in a lecture to the Physical Society of London in February, 1885.
The circular calculating machine of Edmondson
Edmondson returned to the circular stepped-drums mechanism of the machine of Philipp Matthäus Hahn, although the construction of Edmondson is quite different.
The patent drawing of the circular calculating machine of Edmondson
The machine is quite solid, with dimensions 48 x 41 x 15 cm and weight some 20 kg.
Eight number slides are placed radial on the outer fixed portion of the machine. The hinged slide of the straight type of machine (e.g. machine of Colmar) is replaced by a circular plate, carrying 20 figure discs, each of which—depending on its position relative to the number slides and driving handle, respectively—can serve either for recording the result in multiplication, or for setting the figures of the multiplier. Stepping is performed by lifting this plate, rotating it through one-twentieth of a revolution, and lowering it again. To multiply, the figures of the multiplier are set on the middle plate and those of the multiplicand on the slides. The driving handle is then turned to the right and the plate stepped clockwise until all the digits of the multiplier have been brought to zero. The product then appears in the apertures on the middle plate.
The machine of Edmondson, close view
The machine is provided with a zero-setting mechanism with which some, or all of the windows may be set to zero.
Edmondson's calculating machine attracted enough notice to be favourably mentioned in the 1911 Encyclopaedia Britannica, almost thirty years after its introduction.