NotesFAQContact Us
Search Tips
ERIC Number: EJ802706
Record Type: Journal
Publication Date: 2008
Pages: 11
Abstractor: ERIC
Reference Count: 3
ISSN: ISSN-0819-4564
The Mathematics of Sundials
Vincent, Jill
Australian Senior Mathematics Journal, v22 n1 p13-23 2008
As early as 3500 years ago, shadows of sticks were used as a primitive instrument for indicating the passage of time through the day. The stick came to be called a "gnomon" or "one who knows." Early Babylonian obelisks were designed to determine noon. The development of trigonometry by Greek mathematicians meant that hour lines could be determined arithmetically rather than by geometry, leading to more sophisticated sundials. In the first century CE, the Roman architect and engineer Vitruvius described several types of sundials in his "De Architectura" (Lennox-Boyd, 2006, p. 32), including hemispherical, conical and planar dials. Sundials are often constructed to commemorate special events. The many common designs of sundials, such as vertical, horizontal and analemmatic dials, can all be derived by projections of the basic equatorial dial. In this article, the author shows how trigonometry can be used to calculate the positions of the hour lines for vertical and horizontal sundials, with a particular focus on the mathematics underlying a recently-constructed unique horizontal sundial at Piazza Italia in Melbourne. (Contains 17 figures and 2 tables.)
Australian Association of Mathematics Teachers (AAMT). GPO Box 1729, Adelaide 5001, South Australia. Tel: +61-8-8363-0288; Fax: +61-8-8362-9288; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: Australia