Astronomical and meteorological instruments in the 15th century
Astronomical and meteorological instruments in the 15th century
The talented and intelligent Korean people made and used astronomical and meteorological observation instruments on a high level in the 15th century on the basis of the scientific and technological achievements in the preceding periods.
Typical instruments were Kanui(instrument to observe the astronomical phenomena), Honchonui(instrument to observe the or bit of the heavenly bodies), Angbuilku(sundial), and udometer.
Kanui was an instrument for measuring the horizontal coordinates, equatorial coordinates of the heavenly bodies, and time, and it was made by Richon, Jang Yong Sil, etc. in 1432. The original instrument was made of wood and then made of copper elaborately, which was called Big Kanui. In 1434, Ri Chon, Jongcho, Jonglinji and others made a smaller Kanui, knowing that Big Kanui was heavy and inconvenient for the actual observation. This was called Small Kanui.
Kanui was a typical observation instrument showing the development of the astronomical meteorological observation technique of the Korean prople, as it also depends on the instrument measuring the height and azimuth of the heavenly body.
In the 15th century, Honchonui was also invented, and it was an astronomical observatory instrument to measure astronomical values, including the positions of heavenly bodies. The astronomical values which were measured by this metallic instrument are almost similar to those used in astronomy today. A typical example is that the intersection angle of the ecliptic plane and the equatorial plane was set to 24°.
Angbuilgu was made of copper or brass. The structure of this instrument is as follows: there stands a guide pole at the bottom of the dome, and the sight line and the season line are drawn. People can guess the time and the season according to the movement of the pole’s shadow in the instrument. Angbuilgu was the more complete and accurate form of sundial than the sundial with a flat shadow plate. This was because the celestial sphere was reduced to a small spherical shape, and hence there was little error.
The udometer had made its first appearance as the first rainfall measurement instrument in the world. In 1441, a round box-shaped metallic udometer was firstly made, and then it was remade several times. In the local areas, the udometers were made of ceramic or earthenware, were placed in the courts of the government public offices, and were used to measure the raining time and quantity when it rained.