Marine sextant, 6" radius and reading to 10", with 2 1/2x telescope magnification and battery operated light. Felt lined dovetail box includes original certificate of inspection, dated 16/6/1942.
This is sextant # 29792 and carries the "HUSUN" trademark plate of Henri Hughes and son.

Donated by Kostas Aggelakis
to the Hellenic Archives of Scientific Instruments. The box and the certificate of inspection

Jean-Charles de Borda (1733-1799), navigator and astronomer designed the repetition circle for geodesy and astronomical measurements. This instrument permits to repeat several times the same observation without returning to zero, thus the measuring errors are divided by the number of observations.

Part of a theodolite which consists of a telescope fitted with a spirit level and which is free to rotate about its vertical and horizontal axes.

Functioning:
Used in surveying, navigation and meteorology.the theodolite allows accurate reading of horizontal and vertical angles and is used in surveying, navigation and meteorology.

The sextant consists of a triangular frame, an index arm which can be moved across the bottom arced limb, two sights and two reflecting mirrors. One mirror is moved with the arm, and the other (half of which is transparent) is fixed to one limb. One sight is fixed below this mirror and the other on the opposite limb. The arc of the bottom limb is 60degrees and a venier scale on the index arm allows for more accurate reading.

Functioning:

The sextant consists of a triangular frame, an index arm which can be moved across the bottom arced limb, two sights and two reflecting mirrors. One mirror is moved with the arm, and the other (half of which is transparent) is fixed to one limb. One sight is fixed below this mirror and the other on the opposite limb. The arc of the bottom limb is 60degrees and a venier scale on the index arm allows for more accurate reading.

Functioning

Used at secondary education schools (Gymnasiums). The candle represents the Sun. The apparatus shows the annual movement of the Earth and the inclination of its axis in relation to the plan of its orbit around the Sun which produces the seasons.

Refractive telescope with equatorial mounting, objective diameter 125mm, focal length 2000m, photographic objective diameter 80mm

Reflecting telescope, Newtonian type, used for educational purposes at the University of Athens.
Originally mounted on a tripod, the eyepiece is missing.

The apparatus shows the movement around the Sun of the Earth and the two inner planets, Hermes and Venus and also the Lunar orbit.
The gears

The sextant consists of a triangular frame, an index arm which can be moved across the bottom arced limb, two sights and two reflecting mirrors. One mirror is moved with the arm, and the other (half of which is transparent) is fixed to one limb. One sight is fixed below this mirror and the other on the opposite limb. The arc of the bottom limb is 45degrees and a venier scale on the index arm allows for more accurate reading.

Functioning: