In the Fortin barometer, the level of mercury in the glass at the bottom of the barometer cistern is adjusted to a scale zero, known as the fiducial point, each time a reading is to be taken. The level of mercury in the column is then read against the scale, using a vernier adjustment for extra accuracy.
The Observatory bought 11 barometers of this type in 1899 in order to equip the Greek meteorological stations.
Used at the First Gymnasium of Athens, Plaka.
It consists of a horizontal circle, a magnetic needle and sights, set on a tripod with levelling screws.
Sighting an object thrugh the sights gives the bearings of the object.
The Millionaire was invented in 1893 by Otto Steiger and was the first direct multiplying calculator to be commercially successful. Between 1894 and 1935, 4,655 millionaires were sold.
Map of the sky as viewed from the Earth.
This sphere dates from the period of the first director of the Observatory, George Vouris.
It is made in Austria.
This sphere was in the office of Demetrius Aiginites, director of the Observatory from 1890 to 1934 who brought it from France.
The basic design of a centrifuge consists of a rotor which holds samples and rotates around a fixed axis driven by a motor. More advanced centrifuges may also have lubrication and cooling systems. In addition to this, some centrifuges are capable of creating a vacuum environment around the rotor.