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Hamann Manus · Volume 7

The Type and Its Relatives

Collectors class a calculating machine first by what it can do and how it is driven, and then by its Schaltwerk, its actuating mechanism, meaning the part that turns a digit on the setting levers into that many steps of a result wheel. By the first measure the Manus is an ordinary machine of its day: a hand-cranked, lever-set, four-function calculator, the kind that sat on thousands of office desks between the wars. By the second it is almost unique. It belongs to a class of one maker, the switching-latch machine (Schaltklinkenmaschine), and no one but Hamann’s company and its successors built four-function calculators that way.

7.1 The four classic mechanisms

Figure 1 — The stepped drum of Leibniz and Thomas: a drum with nine teeth of graded length, and a pinion slid along it by the setting control to pick up 0 to 9 of them per turn.
Figure 1 — The stepped drum of Leibniz and Thomas: a drum with nine teeth of graded length, and a pinion slid along it by the setting control to pick up 0 to 9 of them per turn. — Scheme: Christian Hamann, public.bht-berlin.de/hamann.
Figure 2 — The pinwheel of Odhner and Baldwin: a disc with nine sliding teeth, pushed out by a setting ring, so that the wheel itself has 0 to 9 teeth.
Figure 2 — The pinwheel of Odhner and Baldwin: a disc with nine sliding teeth, pushed out by a setting ring, so that the wheel itself has 0 to 9 teeth. — Scheme: Christian Hamann, public.bht-berlin.de/hamann.
Figure 3 — Hamann's proportional lever, used in the Mercedes-Euklid: a lever whose swing is proportional to the digit set, transferring any digit in a single motion.
Figure 3 — Hamann's proportional lever, used in the Mercedes-Euklid: a lever whose swing is proportional to the digit set, transferring any digit in a single motion. — Scheme: Christian Hamann, public.bht-berlin.de/hamann.

Table 1 — The four classic mechanisms

MechanismHow a digit becomes teethClassic machines
Stepped drum (Staffelwalze)a drum with nine teeth of graded length; a pinion slides along it to the digit and is turned by that many teethThomas arithmometer, Burkhardt, Saxonia and Archimedes of Glashütte, the Curta
Pinwheel (Sprossenrad)a wheel whose teeth slide out: setting the lever pushes out that many teeth, which mesh once per turnOdhner, Brunsviga, Thales, Walther, Triumphator, Facit
Proportional lever (Proportionalhebel)a lever or rack moved a distance proportional to the digitMercedes-Euklid (Hamann’s earlier invention)
Switching latch (Schaltklinke)a full gear wheel, loose on the shaft, coupled to it by a latch for as many teeth as the digitHamann Manus and all later Hamann machines

Peter Haertel’s classification of mechanical calculator mechanisms states it outright: “The inventor of the switching-latch principle is Dr. h.c. Christel Hamann (1870–1948).” His classification credits Hamann with the proportional lever as well, which makes Hamann one of very few designers credited with inventing two of the classic mechanisms.

Figure 4 — Inside a Mercedes-Euklid 22: one input unit in place with the key for 3 pressed, and the proportional levers under the gear wheels, Hamann's other mechanism.
Figure 4 — Inside a Mercedes-Euklid 22: one input unit in place with the key for 3 pressed, and the proportional levers under the gear wheels, Hamann's other mechanism. — Photo: Christian Hamann, public.bht-berlin.de/hamann.

7.2 What the switching latch gave Hamann

The 1920 patent lists the advantages Hamann wanted, and the Manus delivered them:

  • Ordinary gear teeth throughout, in place of pinwheel teeth sliding in slots, for “the quietest possible running” and long wear.
  • Setting parts that stand still while the machine runs, so the number set can be read in windows. On a pinwheel machine the setting turns with the drum.
  • One crank direction for everything, with subtraction done by a reversing gear. A pinwheel machine subtracts by turning backwards.
  • Places driven one after another, which keeps the crank light and makes the drum’s own tens carry possible.
  • Automatic division, because the machine can detect its own overdraft and move its own carriage.

The cost was complexity. A pinwheel drum can be lifted out, cleaned and dropped back in an afternoon. A switching-latch drum, as the repair volume explains, cannot.

The Arithmeum in Bonn notes that Hamann was not the first to try latches: “Hamann was the first to successfully use this mechanism in calculating machines manufactured in series production. The switching latches that Dietzschold and Weiss had developed before … never got beyond the stage of a prototype.” The ratchet principle also appears in simple adding devices, which Rechnerlexikon files under the same heading, but those are adders, not four-function calculators.

7.3 The competitors

The Manus was built to look like the pinwheel machines it competed with. These were its rivals on the office desk.

Table 2 — The competitors

MakeWhere and whenMechanismDifference from the Manus
Odhner / Original-OdhnerSt Petersburg from 1890; Göteborg from 1917pinwheelcrank turned backwards to subtract; division by hand. The Manus copied its outward form and dimensions
BrunsvigaGrimme, Natalis & Co., Braunschweig, from 1892 (Odhner licence); Brunsviga Maschinenwerke 1927; to Olympia 1959pinwheelthe market leader in Germany; reverse crank; no automatic division on hand models
ThalesThaleswerk, Rastatt; model A from 1911 into the 1950spinwheelas the Brunsviga
TriumphatorLeipzig, 1904–1965; about 380,000 madepinwheellarge production; nationalised after 1948
WaltherZella-Mehlis, later Niederstotzingenpinwheelbuilt pinwheel machines for Mercedes in the 1920s–30s; post-war WSR “Schnellrechner” with back-transfer
FacitStockholm 1918, Åtvidaberg from 1922pinwheelten-key setting from 1932
ArchimedesReinhold Pöthig, Glashüttestepped drumslide setting, stepped drums
Mercedes-EuklidMercedes Büromaschinen, Zella-Mehlisproportional leverHamann’s earlier design; heavier office machine, automatic division from 1915
Figure 5 — An Original-Odhner lever-set pinwheel calculator: the machine whose outward form and dimensions the Manus deliberately copied.
Figure 5 — An Original-Odhner lever-set pinwheel calculator: the machine whose outward form and dimensions the Manus deliberately copied. — Science Museum Group Collection, London.
Figure 6 — A Brunsviga 13Z, from Braunschweig, the dominant German pinwheel machine.
Figure 6 — A Brunsviga 13Z, from Braunschweig, the dominant German pinwheel machine. — Science Museum Group Collection, London.
Figure 7 — A cutaway Triumphator, from Leipzig, showing the pinwheels that the Manus replaced with latched gear wheels.
Figure 7 — A cutaway Triumphator, from Leipzig, showing the pinwheels that the Manus replaced with latched gear wheels. — Science Museum Group Collection, London.
Figure 8 — A cutaway Walther WSR 160, a post-war pinwheel machine with back-transfer.
Figure 8 — A cutaway Walther WSR 160, a post-war pinwheel machine with back-transfer. — Science Museum Group Collection, London.
Figure 9 — An Archimedes model H from Glashütte, a stepped-drum machine.
Figure 9 — An Archimedes model H from Glashütte, a stepped-drum machine. — Science Museum Group Collection, London.
Figure 10 — A Thomas de Colmar arithmometer, number 2034, the stepped-drum machine from which the commercial calculator industry grew.
Figure 10 — A Thomas de Colmar arithmometer, number 2034, the stepped-drum machine from which the commercial calculator industry grew. — Science Museum Group Collection, London.

The German calculator industry was concentrated in a few towns: Glashütte in Saxony (Burkhardt, Saxonia, Archimedes), Braunschweig (Brunsviga), Leipzig (Triumphator), Zella-Mehlis (Mercedes, Walther), Rastatt (Thales) and Berlin, where DeTeWe built the Hamanns in its telephone works.

7.4 Hamann’s other machines

Every Hamann machine after 1925 used the switching latch. The line, as far as it can be reconstructed:

Table 3 — Every Hamann machine after 1925 used the switching latch. The line, as far as it can be reconstructed

MachineYearsCapacityNotes
Manus A–F, R1925–19599 × 8 × 13the hand-cranked lever-set machine; R with back-transfer
Automat (Z, Y, X, V)from c. 1930—electric, automatic multiplication (US 1,968,201); the V with short-cut multiplication
Selecta1931–469 + 8 × 9 × 16electric, two full keyboards (multiplicand and multiplier); about 5,000 made
Deltafrom 19349 × 8 × 16 / 13 × 8 × 16full keyboard, motor, automatic division; about 1,200–1,500 made
Elma1930s–40s9 × 8 × 13essentially a Manus with an electric motor as well as a crank; about 7,000 made
Hamann 3001953–599 × 8 × 16ten-key keyboard, double back-transfer; DM 1,980 in 1958
Hamann E1953–599 × 8 × 16electric keyboard machine (not the Manus E); about 5,100 made
Automat S1954–589 × 8 × 16electric, automatic carriage; DM 1,750 in 1958
Automatic 5001959–629 × 8 × 16sold in America as the Marchant Tenkeymatic
5051962–68—the last non-printing Hamann
Figure 11 — Christel Hamann's last major patent, DE 919,787 (filed 29 October 1949): the back-transfer device of the Manus R.
Figure 11 — Christel Hamann's last major patent, DE 919,787 (filed 29 October 1949): the back-transfer device of the Manus R. — Patent drawing via Rechnerlexikon, public domain.
Figure 12 — A Hamann 300 of 1953, the ten-key machine with double back-transfer, restored for the Energie-Museum Berlin.
Figure 12 — A Hamann 300 of 1953, the ten-key machine with double back-transfer, restored for the Energie-Museum Berlin. — Photo: Christian Hamann, public.bht-berlin.de/hamann.
Figure 13 — A Hamann Automat E electromechanical calculator.
Figure 13 — A Hamann Automat E electromechanical calculator. — Photo: Maksym Kozlenko, CC BY-SA 4.0, via Wikimedia Commons.
Figure 14 — A Hamann Selecta SPU of 1934, with two full keyboards, one for the multiplicand and one for the multiplier.
Figure 14 — A Hamann Selecta SPU of 1934, with two full keyboards, one for the multiplicand and one for the multiplier. — Photo via Wikimedia Commons.
Figure 15 — A Hamann Elma: the Manus mechanism with an electric motor added.
Figure 15 — A Hamann Elma: the Manus mechanism with an electric motor added. — Science Museum Group Collection, London.
Figure 16 — A Hamann Delta, serial 1368, a full-keyboard electric machine of the 1930s on the same switching-latch principle.
Figure 16 — A Hamann Delta, serial 1368, a full-keyboard electric machine of the 1930s on the same switching-latch principle. — Photo: Jaap Scherphuis, jaapsch.net/mechcalc.
Figure 17 — A Hamann Automat T.
Figure 17 — A Hamann Automat T. — Photo via Wikimedia Commons.
Figure 18 — The Hamann Automatic 500, serial 157717, 1960, made by Hamann Rechenmaschinen GmbH after the sale to Marchant, and sold in the United States as the Marchant Tenkeymatic.
Figure 18 — The Hamann Automatic 500, serial 157717, 1960, made by Hamann Rechenmaschinen GmbH after the sale to Marchant, and sold in the United States as the Marchant Tenkeymatic. — Photo: Christian Hamann, public.bht-berlin.de/hamann.

7.5 How it ended

The Manus R was the cheap end of DeTeWe’s range by the 1950s: DM 598 in 1958, against DM 1,000–2,000 for the electric keyboard machines. In 1958 DeTeWe sold the calculating-machine works to the American firm Marchant, and the business continued as Hamann Rechenmaschinen GmbH, later SCM Deutschland. One account says Siemens bought DeTeWe in 1959 and then sought a buyer for Hamann; the German sources do not confirm that. The Manus R ended in 1959, the same year the Automatic 500 appeared. Electronics finished the rest: the last Hamann, the 505, was made until 1968.

The switching latch went with it. Unlike the pinwheel and the stepped drum, which every maker used, it had only ever belonged to one designer.

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