GEOID: see GEODESY.
a former fortress of the Turkomans, in the Turkmenistan S.S.R., lat. 38° 12' N., long. 57° 58' E., in the oasis of Akhal-tekke, on the Transcaspian railway, 28 m. N.W. of Askabad. It consisted of a walled enclosure 1 m. in circuit, the wall being 18 ft. high and 20 to 30 f t. thick. In December 188o the place was attacked by 6,000 Russians under General Skobelev, and after a siege of twenty-three days was carried by storm, although the defenders numbered 25,000. A monument and a small museum commemorate the event.