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the luminous, five-pointed, ruby-colored stars mounted on five towers of the Moscow Kremlin. The first of the Kremlin stars was mounted on the Spasskaia Bashnia, or Tower of the Redeemer, on Oct. 25, 1935. By Nov. 1, 1935, Kremlin stars were mounted also on the Troitskaia Tower (Trinity Tower), Nikol’skaia Tower (St. Nicholas Tower) and Borovitskaia Bashnia (Tower of the Woods). These stars replaced huge, double-headed copper eagles that had been on the towers since the prerevolutionary period. The body of the Kremlin stars was made of stainless steel and covered with gilt copper sheets. The stars were decorated on both sides by ornaments in the shape of the hammer and sickle made of Ural gems. The design of the first Kremlin stars was not successful; the gem surfaces soon grew dim and had to be refaced. In 1937, on the 20th anniversary of the October Socialist Revolution, the original stars were replaced by stars made of ruby-colored glass. A star was also mounted on the Vodovzvodnaia Tower (Water Tower).
The dimensions and the shape of each of the five Kremlin stars were determined by the height and architectural design of the corresponding tower. The distance between the points of the star mounted on the Vodovzvodnaia Tower is 3 m. This distance on the Borovitskaia Tower is 3.2 m; on the Troitskaia Tower, 3.5 m; and on the Nikol’skaia and Spasskaia towers, 3.75 m.
The supporting stainless steel structure of Kremlin stars has the shape of a five-pointed three-dimensional star whose ends are shaped like a pyramid. This structure has been designed to withstand a maximum pressure of hurricane winds equal to 2 kilonewtons per square meter (200 kilograms-force per square meter). Despite their considerable weight (about 1 ton) the Kremlin stars turn rather easily with changing winds. Owing to their shape, their front side is always against the wind.
To provide good visibility against the sky, the Kremlin stars are illuminated from within by incandescent lamps. Refractors consisting of prismatic glass plates provide a uniform distribution of light flux. The power output of the lamps (3.7 kW in the stars of the Vodovzvodnaia and Borovitskaia towers and 5 kW in the rest) provides good visibility of the stars both at night and during the day. The lamps have a high luminous efficiency, equal to about 22 lumens per watt. The lamps with a power output of 5 kW measure 383 mm long and have a bulb diameter of 177 mm. Each lamp generates a large quantity of heat, necessitating special cooling provisions for the stars. Thus, each tower has two ventilators. In replacing the original stars by glass stars, it was necessary that (1) the stars shine with sufficient brightness at night, (2) the stars retain their ruby-red color in daylight, and (3) the incandescent filaments be invisible. The second requirement was particularly difficult to meet since red glass when illuminated from the outside and not by transillumination appears to be almost black. The present glass of the stars, which was installed in 1946, consists of ruby-colored and milky-white glass interstratified with transparent crystal glass. The white glass effectively scatters the light of the lamps, at the same time reflecting a considerable part of daylight and thus, softening the darkness of the ruby glass in daylight. To achieve a greater degree of contrast and to accentuate the pointed shape of the stars, different hues of ruby-colored glass are used. However, each of the hues transmits only red rays with a wavelength of less than 0.62 μm. The thickness of the glass used in the Kremlin stars is from 6–8 mm; the glass area constitutes approximately 6 sq m.
Servicing mechanisms for the Kremlin stars are located in the towers. Special hoisting equipment makes it possible to remove dust and soot from the interior and exterior of the stars. Mechanized devices replace burned-out bulbs within 30–35 min. The control of the equipment and mechanisms of the Kremlin stars is concentrated in a central station, which receives data on the operating conditions of the lamps.