Editing Sundial (section)

===Human shadows===
The length of a human shadow (or of any vertical object) can be used to measure the sun's elevation and, thence, the time.<ref>{{harvp|Rohr|1965|p=15}}; {{harvp|Waugh|1973|pp=1–3}}</ref> The [[Venerable Bede]] gave a table for estimating the time from the length of one's shadow in feet, on the assumption that a monk's height is six times the length of his foot. Such shadow lengths will vary with the geographical [[latitude]] and with the time of year. For example, the shadow length at noon is short in summer months, and long in winter months.
 
[[Chaucer]] evokes this method a few times in his ''[[Canterbury Tales]]'', as in his ''Parson's Tale''.{{efn|
[[Chaucer]]: as in his ''Parson's Tale'':
: It was four o'clock according to my guess,
: Since eleven feet, a little more or less,
: my shadow at the time did fall,
: Considering that I myself am six feet tall.
}}

An equivalent type of sundial using a vertical rod of fixed length is known as a ''[[backstaff|backstaff dial]]''.