An analemmatic sundial uses a moveable vertical pin to cast a shadow onto a horizontal scale. The hours are marked as a series of points around the circumference of an ellipse, quite different to the fixed hour lines for conventional sundials. Because the sun’s position varies with the seasons, the vertical pin must be set in a different position for each day of the year.
It is possible to make an analemmatic sundial suitable for a park, public garden, or schoolyard using a person as the moveable gnomon. The shadow of the person’s own body then tells solar time, provided he stands on the correct position for that day’s date.
Such sundials have been hugely successful because the people using them are actively involved in doing something, and not just looking on, so we have termed them ‘sundials of human involvement’, or ‘human sundials’.
When using a normal analemmatic sundial, you stand at the appropriate position on a date scale which is laid out along a North-South axis. The position of your shadow with respect to the hour markers indicates Solar Time and you must then add the Time Correction appropriate to your location and the date to obtain Clock Time.
An interesting variation by Sundials Australia to the standard analemmatic sundial which measures only solar time, allows you to tell approximate clock time directly using an analemmatic sundial by slightly displacing each hour marker around the elliptical circumference, and moving the vertical gnomon around a ‘figure of 8’ pathway (known as an analemma because of its superficial similarity to the analemmas of a projection sundial) rather than along the straight North-South line of a conventional analemmatic sundial.
The precise differences between a standard solar time analemmatic sundial and our clock time analemmatic sundial depend very much on the latitude and longitude for which they are designed.
We suggest that an interactive 'human' sundial of this type covers an area about 5 x 3 metres.
The hour markers can be raised rocks or pillars, or can be shaped or mosaic plates set on the ground.
Because most people are unfamiliar with such sundials, we suggest that a conventional, horizontal sundial be located nearby so that users can check the human sundial against a time-telling method with which they are more familiar.
Using the Human sundial at the Australian Botanic Garden Mount Annan, near Camden NSW
Human and Horizontal sundials at the Maria Creek Sculpture Park at Kingston SE, South Australia
Central Analemma on the Human Sundial at the Australian Botanic Garden Mount Annan.
A horizontal sundial is located on the rock pedestal behind the human sundial.
(Photo credit: Jaime Plaza, Royal Botanic Gardens & Domain Trust)
Human sundial at Mount Stromlo Observatory.
This and our horizontal sundial located nearby were amongst the few items which survived the catastrophic 2003 bush fires.
Should you wish to commission a Human sundial for your local park or school, or even for your own back yard, then please Contact us.