History Gnomon

a gnomon in euclid book ii

a painted stick dating 2300 bce excavated @ astronomical site of taosi oldest gnomon known in china. gnomon used in ancient china second century bc onward in order determine changes in seasons, orientation, , geographical latitude. ancient chinese used shadow measurements creating calendars mentioned in several ancient texts. according collection of zhou chinese poetic anthologies classic of poetry, 1 of distant ancestors of king wen of zhou dynasty used measure gnomon shadow lengths determine orientation around 14th-century bc.

the ancient greek philosopher anaximander (610–546 bc) credited introducing babylonian instrument ancient greeks. ancient greek mathematician , astronomer oenopides used phrase drawn gnomon-wise describe line drawn perpendicular another. later, term used l-shaped instrument steel square used draw right angles. shape may explain use describe shape formed cutting smaller square larger one. euclid extended term plane figure formed removing similar parallelogram corner of larger parallelogram. indeed, gnomon increment between 2 successive figurate numbers, including square , triangular numbers. ancient greek mathematician , engineer hero of alexandria defined gnomon which, when added entity (number or shape), makes new entity similar starting entity. in sense theon of smyrna used describe number added polygonal number produces next 1 of same type. common use in sense odd integer when seen figurate number between square numbers.