<!-- These images show the analemma- but are not analemmetic dials- where the gnomon is moved to a particular spot on the analemma --read the references given below
are a common feature at science museums
and occasionally in public places. They exploit the fact that the sun travels in a predictable pattern over the course of a year called the analemma
and trace the projection of an object's shadow to measure time, not only the hours, as in normal sundials
, but also weeks and months.
Accurate dials of this type are popular in public places, using a ball at the tip of a flagpole as the nodus
, with the sundial face painted on or inlaid in the pavement. A less accurate version of the sundial is to lay out the hour marks on a pavement, and then let the user stand in a square marked with the month. The user's head then forms the gnomon
of the dial. In middle latitudes, the ellipse with the hour-marks will be about six meters wide, so the shadow of the head of the beholder falls near it most of the time.
An analemmatic sundial uses a vertical gnomon
and its hour lines are the vertical projection of the hour lines of a circular equatorial sundial onto a flat plane.Rohr (1965), pp. 100–106; Waugh (1973), pp. 108–115; Mayall and Mayall, p. 60–61,... Read More