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Slide rules in Hungary

Brief history

The first slide rules began to appear around the same time in Europe. In Budapest there were several shops where slide rules manufactured by the major german factories (A. W. Faber later Faber-Castell, Albert Nestler and Denner & Pape) in the early 1900s. These rules are precision instruments with hight production costs, so these are very expensive. Because of this extensive use has been impossible at this time. Although these companies produced cheaper rules for use in schools with less scales or much simple design, some of hungarian distributors were planning their own slide rules to produce. The company named Calderoni sell instruments mostly for teaching purposes, two opticians - László and Gyula Juszt produced cheaper versions of the standard slide rules under the name GENIE. These rules were made of cheaper wood with simpler or missing steel springs and reinforcing, the scales were printed on paper pieces which have been polished before glued on.
The Gamma Works for Precision Instruments founded a subsidiary company for selling both their own products both imported ones, so their name - Gamma K. F. T. (Ltd)- appeared on some drawing or measuring istruments, so in german slide rules too.

After the World War II, in the end of 1940s the changed politics in the country decided to import required goods from other socialist countries - due to restricted amount of foreign currency available, but the big factories produced slide rules were in imperialists' territory. Only the GDR and the USSR were so fortunate to have such plants but they weren't producing enough to supply all the socialist countries. So more nations had to build their own factories; in Hungary the Gamma started production in 1948, in Czechoslovakia the newly founded corporation Logarex in 1951. Moreover there were smaller companies or privates which have produced slide rules in smaller amounts for mostly teaching purposes - the former Calderoni was nationalized and renamed to ITG (Iskolai Taneszközök Gyára - Factory of School Demonstration Tools), or for example Károly Kökény teacher in Miskolc who created cheap "exercising slide rule" made of paper.

ROTOR

There were a very interesting hungarian circular slide rule named Rotor which have been produced by Telefongyár (Factory of telephones) from 1933 to 1938 under their own patent. This is two new silver (German silver) discs - a bigger outer and a smaller inner - connected together with an index, and has logarithmic scales on the front and trigonometric precision scales on the back. The production has been abandoned due to increased military needs.

Socialist relations

The east german REISS factory nationalized in 1945, produces increasing amounts of professional slide rules under the name VEB Mess- und Zeichengerätebau (People's Factory of Measuring and Drawing Tools). They manufactured first slide rule since 1912, but the true breakthrough was in 1953 when the first aluminium rule was made. These metal instruments have been produced to 1972, and were well-known in Hungary in the 1960s, especially their type 3223 named Progress. Both REISS, both the other company in GDR (Meissner KG which was nationalized only in 1972, when renamed to VEB Mantissa) used plastic to produce duplex (double-sided) slide rules. Due to restructuring of the german industry the two slide rule-making plant was merged in 1974. From Meissner, later Mantissa branded duplex rules, small amounts are imported, so the basic models (Rietz, Mono Rietz, Darmstadt, Darmstadt II) were available in Hungary too.

The czechoslovakians were is same situation as the hungarians, but they founded company named Logarex only in 1951 for producing drawing instruments, rulers and slide rules from plastic. Later Logarex has been fusioned to the famous Koh-I-Noor Hardtmuth corporation. Logarex manufactured a large number of slide rules: cheaper ones made of colored plexiglass, and more expensive models for professional purposes made of imported plastic with increasing cooperation with west german company Aristo (Dennert & Pape). Almost all types were imported in smaller or bigger amounts to Hungary, so these were very popular.

To meet the mass demands, in addition to the domestic production the soviet relation was the solution. In the USSR the factory at Leningrad (in those days and now Saint Petersburg) was the first plant in the country producing slide rules since the 1910s. This plant produced slide rules to 1990s, almost the same type over the century! The soviet standards (the first revision was dated in 1949) dictated the specifications for each type so rules produced in different factories were almost the same. There were only few basic types: the 10-inch (25 cm) LSLO-250-10 (later -11) wooden rules with 10 (11) scales, the pocket version of that (LSLO-125-10), and from the end of 1960s there were duplex variations with 9 scales for schools and 19 scales for professional purposes (LSDL-250-9 and -19 only in Leningrad), finally rules with 10 or 14 scales made of plastic (LSLO types with suffix -P, only in Kiev) from the end of 1970s when this industry were dying all over the world except the USSR. An interesting instrument was made by the Watch Factory of Moscow, the KL-1 type circular slide rule which seems to be a pocket watch.
The soviet rules sold for equivalent prices as the hungarian models. Although these had fewer scales, the interrupts in domestic supply made these rules very popular in Hungary.

At the end of the slide rule era

In the second half of 1960s it has been seen that electronic calculators that were more popular as they become cheaper would replace the slide rule. The factories were committed to lower the production cost so the easier produced plastic rules became more popular. In the 1970s when the first pocket-size "electronic slide rules" (pocket calculators with scientific function set) became available and cheaper month by month, the manufacturers had to lower the price, later closed down the production lines. In these days the Hungarian corporations for foreign trade started to import slide rules produced by Faber-Castell, so in specific intervals these rules were sold off by 50 %. The socialist countries closed down their factories too, only two plants in the USSR produced specific types of slide rules to 1991: the NL-10 series of navigation rules widely used by the army were built at the Leningrad Orgtehnika factory, and the plastic rules still have been manufactured in Kiev.

Further reading

Slide rules manufactured in Hungary
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