Petrie (1883) pp38. For 2600 BC, bisecting the semi-circular path of star 10i Draconis around the North Celestial Pole during the half-day darkness of a mid-winter evening would easily provide accurate true north. See Nature 412:699 (2001); further sources and discussion available via DIO （页面存档备份，存于互联网档案馆）.
Petrie (1883) pp38. For 2600 BC, bisecting the semi-circular path of star 10i Draconis around the North Celestial Pole during the half-day darkness of a mid-winter evening would easily provide accurate true north. See Nature 412:699 (2001); further sources and discussion available via DIO （页面存档备份，存于互联网档案馆）.
