ИСТИНА

It is well known that planispheric astrolabes used to be made of brass. Due to the strength of this metal, about two thousands of such instruments have been preserved up to now. The largest one has a diameter of 84 cm and is displayed in Galileo Museum in Florence. However, medieval astrolabists also made wooden instruments. The best-known wooden astrolabes of the 16th century were those crafted by George Hartmann in Nuremberg. Unfortunately, wood is a perishable material and only a few astrolabes survived, while others just vanished. Fortunately, the last statement does not apply to the wooden astrolabe, which is now kept at the State Hermitage Museum (St. Petersburg, Russia). Its wooden body is covered with lacquer, and although it is three hundred years old, the time has spared it. The alidade is also made wood. Nevertheless, the most critical part -- the rete – is still made of brass, as well as the rule-pointer, while tympans, the number of which is as big as 8 (i.e., 16 sides) are made of cardboard. Due to this successful combination of materials, the astrolabe is 435 mm in diameter, weighs only 2.2 kg. A tool of this size, if made of metal, would be too heavy to hold in hands. This astrolabe may be the largest wooden astrolabe in the world. Its uniqueness, however, is not limited to its size. It is an instrument made comparatively late, as is written on it, by Mohammed Karim at the order of a mighty ruler Aga Qanbar-Ali (the name has not been identified) in 1720. On the internal surface of its body there is a gazetteer of 94 cities, each of which has five parameters, i.e., longitude, latitude, Qibla, distance to Mecca and the direction of the azimuth of the Qibla with respect to the four cardinal points. This is a very rare set of parameters, especially the distance to Mecca – al-masāfat. Another, (but no the last one) feature of the instrument is that all the numbers are written in letters instead of figures (for example, the quantity 350 on the limb is written in words "three hundred fifty"). Because of this, virtually the entire surface of the astrolabe is covered by inscriptions. No similar instruments have been found so far.