The first computers were mechanical machines built using gears and levers.
Parts or components of these could be moved and connected in a way that simulated the relationship between different variables in a mathematical equation. By moving a gear or pulling a lever, these variables could be changed, and the results of such actions could be seen in another set of gears, the new positions of which gave the answer that the operator was looking for.
But in 1936, Russian engineer Vladimir Lukyanov built a mechanical computer that used water instead of gears and levers for calculations.
Lukyanov was one of the engineers who worked on the construction of the Troitsk-Orsk and Kartaly-Magnitnaya railways in the late 1920s. To ensure the quality and durability of reinforced concrete structures, the engineers poured concrete only in the summer.
Despite this, cracks still appeared in concrete when temperatures dropped below freezing in winter. Lukyanov suggested that this can be avoided if a thorough analysis of the temperature change of the concrete mass is carried out, depending on the composition of the concrete, the cement used, the technology of work and external conditions.
Lukyanov began to study the temperature regime in concrete masonry, but the existing calculation methods could not provide a quick and accurate solution to complex differential equations related to the temperature regime.
In his search for a new approach to solving the problem, Lukyanov discovered that the flow of water is in many ways similar in its laws to the distribution of heat. He came to the conclusion that by building a computer where the main component is water, it will be possible to recreate an invisible thermal process.
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In 1936, Lukyanov built the first model of his "water integrator" at the Institute of Railways and Construction (now the Central Scientific Research Institute of Transport Construction, or TsNIIS). At the time, it was the only computer that could solve partial differential equations.
Lukyanov's water integrator looked impressive. It was the size of a closet and consisted of several pipes and pumps interconnected. The water level in the various chambers was stored numbers, and the flow rates between them were mathematical operations. The result was displayed as a diagram.
The first water integrator models were made of roofing iron, sheet metal and glass pipes and were used only for calculations in the field of heating technology. The improved models were able to solve more complex problems, which significantly expanded their application.
In the 1950s, an integrator was built, parts of which could be removed and combined in different ways depending on the nature and complexity of the problem being solved. The use of a water integrator became so widespread that the machine began to be mass-produced for use in laboratories and educational institutions throughout the Soviet Union. It was widely used in solving construction problems in the sands of Central Asia and permafrost, to study the temperature regime of the Antarctic ice sheet, in rocketry, and so on.
Water integrator Lukyanov, oddly enough, remained relevant for a long time, even after the invention of electronic computers. It wasn't until the 1980s, with the development of small and high-speed digital computers, that the water integrator capabilities began to look obsolete.
Currently, there are only two Lukyanov water integrators; they are kept in the Polytechnic Museum in Moscow.