Herzstark’s daughter The pocket mechanical calculator Jenny Smith

In the Surveying and Geomatic places: not enough for an invoice or 1. reset the sliders to zero, Engineering Collection at the a blueprint.2 These clients needed with carriage in position 1 University of Melbourne is a ‘Curta’ an accurate four-function handheld 2. enter 133 using the sliders model field calculator, made in 1958 calculator. 3. pull up the crank and make by Contina AG of Liechtenstein, Herzstark developed a design one subtractive revolution: serial no. 40349 (pictured opposite). based on a series of stepped drums 133 × (–1) This instrument, an example of the wrapped around a cylinder. The same 4. set carriage in position 2 first handheld mechanical calculator, set of gears could thus be used for (experienced users could do has all the characteristics of a cult each consecutive calculation, which this with the left hand) gadget: it is small, ingenious, practical meant the machine could be held in 5. make one subtractive and elegant. It was widely considered one hand and worked with the other. revolution: 133 × (–10) the most reliable on the market until But two problems remained: 6. set carriage in position 3 cheaper electronic calculators were mechanical calculators could not 7. push crank down 3 millimetres mass-produced. It also has a long, borrow or carry numbers. Herzstark for addition, and make one strange, and somewhat tragic history. managed to solve both problems by additive revolution: 133 × 100 Its inventor, Curt Herzstark using two carriages: one for addition, 8. the result, 11,837, is shown in (1902–1988), was the son of an the other for subtraction, together the result counter. Austrian manufacturer of calculators. with a revolution counter. By the 1920s he was working as a This allowed for nines- Thus—in three revolutions rather precision mechanic in his father’s complement calculation, or simulated than seventeen—the machine factory, which taught him ‘to think subtraction by addition.3 For example, calculates 133 × (–11 + 100), equal out a project from the beginning, to find 169,437 minus 1,958, subtract to 133 × 89.4 Later manuals included how [to] produce something in a each digit of 001958 from nine to algorithms for cubes and square reasonable way’.1 find the nines complement: 998,041. roots.5 Portable calculators at that Adding this to 169,437 gives The design was all but finished by time needed a separate set of gears 1,167,478. Removing the highest- 1937—and then came the Anschluss. for each calculation, which made order digit (leaving 167,478) and The Herzstark factory was ordered them look, and weigh, like early adding 1 gives the answer: 167,479. to build measuring devices for the typewriters. On sales trips, Herzstark Multiplication and division were German armed forces. In 1943 two heard complaints from engineers, calculated on a similar principle: employees were arrested for listening architects and others, who could the user simply lifted the crank a to and transcribing English radio not move to what was essentially a few millimetres to engage the other broadcasts, and Curt Herzstark was desktop machine every time they carriage. To solve the problem of sent to Buchenwald. As a well-known needed to make a calculation. Slide carrying tens, the machine included a engineer, he was put to work in the rules could not add or subtract and revolution counter, so that to calculate factory attached to the camp, where were accurate only to three decimal 133 × 89, the operator could simply: both he and his idea for a pocket

28 University of Melbourne Collections, issue 19, December 2016 Contina AG (Liechtenstein), ‘Curta’ field calculator with case, 1958, serial no. 40349, metal and plastic, 10.7 × 5.3 cm (calculator). Reg. no. 20, Surveying and Geomatic Engineering Collection, University of Melbourne.

calculator were recognised. Herzstark Jenny Smith works in administration in the Department of Infrastructure Engineering at was offered the chance to draw and the University of Melbourne. In 2011–12 she develop his calculator after hours, audited the School of Engineering’s cultural with the idea that the model would collections, including the Surveying and be given to the Führer as a present Geomatic Engineering Collection. after the war, and Herzstark, whose The Surveying and Geomatic father was Jewish and mother was Engineering Collection is on display Christian, might be made an ‘Aryan’ in the hallways of the Department of and allowed to live. The drawings Infrastructure Engineering, Engineering Block C, Level 4, and can be viewed were finished just before the whenever the building is open. See also liberation of Buchenwald. Production www.ie.unimelb.edu.au/collection. began in 1948 in Liechtenstein, and continued until 1972. 1 Curt Herzstark, Oral history interview, Herzstark had originally 1987, Charles Babbage Institute. University called his machine the ‘Lilliput’, of Minnesota Digital Conservancy, but salespeople did not like the http://hdl.handle.net/11299/107358, viewed 15 August 2016. ‘cleverness’ of the name. A sales 2 Herzstark, Oral history interview. correspondent suggested that 3 Cliff Stoll, ‘The curious history of the the machine was its inventor’s first pocket calculator’,Scientific American, vol. 290, no. 1, January 2004, pp. 82–9. ‘daughter’, and should therefore 4 Peter Kradolfer, ‘Curt Herzstark and be called the ‘Curta’, a feminine his pocket calculator CURTA’, Backup: version of Hertzstark’s first name.6 Informatikzeitschrift für Schule und Its mechanical operation is not only Weiterbildung, no. 1, 1989, pp. 41–5, www.vcalc.net/cu-bckup.htm, viewed reassuringly tactile and interactive, 15 August 2016. allowing the user to feel each number 5 [David G. Hicks], ‘Curta handhelds’, as it is entered and to check the The Museum of HP Calculators, www. hpmuseum.org/ffcurta.htm, 1995–2013, results, but so robust that it became viewed 15 August 2016. 7 a favourite among car rally drivers. 6 Herzstark, Oral history interview. From the later 1940s until the 7 Stoll, ‘The curious history of the first pocket 1970s, approximately 149,000 Curta calculator’, p. 89. 8 Rick Furr, ‘The Curta Calculator page’, calculators were produced and www.vcalc.net/cu.htm#stats, viewed exported around the globe.8 Many 15 September 2016. were used by students, academics and engineers, such as this example now on display at the University of Melbourne.

Jenny Smith, ‘Herzstark’s daughter’ 29