From ancient times, the Koreans made astronomical observations with the help of their inventions to know about seasons and seasonal divisions accurately. On this basis, they began to do farming and have a scientific comprehension of outer space and nature.

The constellations carved on dolmens in the period of Ancient Joson (early 30th century BC-108 BC), the astronomical chart carved on a stone in Koguryo (277 BC-AD 668) and the Kyongju Chomsongdae Observatory in Silla (AD early mid-1st century-AD 935) showcase the level of cultural development in those days and prove that the Korean ancestors made scientific astronomical observations by means of various devices.

Honchonui, an astronomical observation instrument, is one of excellent heritage created by the Korean nation.

It was used for measuring such astronomical figures as the position of celestial bodies.

In view of structural design, it consists of graduated circles and gunsights attached to their central axes. A gunsight without lens is similar to the present telescope.

In general, astronomical observation was conducted in such a way as to take aim first at a relevant celestial body by means of gunsights and reading the graduations of relevant circles in targeted positions.

Such astronomical observation instrument as Honchonui was also recorded in the Chronicles of the feudal Joson dynasty (1392-1910).

According to the record, Kanui (a kind of simple-structured Honchonui) was made of wood for the first time in 1432, and it was used for measuring the arctic altitude of the capital. Its measurements were very accurate at that time.

Based on it, Kanui was made of copper in 1433 and it was remodelled into a smaller one in 1434 for more convenient usage. Later, it was improved several times.

In the 19th century, its structure was further brought to perfection and big strides were made in making mathematical calculations of observed values.

An astronomer Nam Pyong Chol (1817-1863), based on his studies of various books at home and abroad and analysis of the merits and demerits of all successive instruments, designed a new type of Honchonui.

Unlike the existing instruments, it was designed to set up newly a circle with which to convert the Equatorial pole into the Ecliptic pole and the Ecliptic pole into the Zenith at will. As a result, astronomical observations could be made in a diversified way.

He wrote a book Uigijipsol dealing with the observation instruments, which said that such a multi-purpose Honchonui made it possible to measure 19 kinds of astronomical figures, including the altitude of the North Pole and 24 divisions of the year.

A mathematician Ri Sang Hyok (1810-?) in his collection of maths papers Sansulgwangyon (intensive studies of relevant sector of arithmetic) made clear the uncertainty of a Western mathematician’s method of calculation in a book published in a foreign country, and specified his own methods for calculating the results of astronomical observation more easily.

As seen above, the Korean people made and developed excellent observation instruments, thereby rendering tangible services to enriching the storehouse of science and culture of mankind.

Ri Jin Song, academic researcher at Sci-Tech Complex