Sundial, Bede's World, Jarrow

Image: © Andrew Curtis Taken: 16 Jul 2010

This is an example of an analemmatic sundial. This is a horizontal sundial in which the shadow-casting object (in this case the observer) is vertical, and is moved depending on the date http://plus.maths.org/issue11/features/sundials/ You stand on the correct month inscribed along the line within the central circle and your shadow (if the sun is shining) tells the time from hour marks laid out as an outer ellipse. If the sun isn't shining, just look at your watch. The Venerable Bede, as interested in science and art as he was in ecclesiastic history, wrote on the calendar, marine tides and the shape of the Earth. The length of a human shadow (or of any vertical object) can be used to measure the sun's elevation and, thence, the time. He gave a table for estimating the time from the length of one's shadow, on the assumption that a monk's height is six times the length of his foot http://en.wikipedia.org/wiki/Sundial

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