The latitude of Venice is almost exactly forty-five degrees, midway between the Equator and the North Pole. It is therefore a place of mystical balance, not only for the calculation of dials, but in life itself. It is a place where many people find repose, amid their otherwise turbulent existence. Peggy Guggenheim was one of those and it was the relative calm of her life here that allowed her to enjoy her collection. It is on the angle 45o and on the classical rules of the Golden Section that the design of the Guggenheim dial has been based.
The dial actually consists of a series of subsidiary dials within the whole, each with its own gnomon (the raised part of a sundial that casts the shadow). The gnomons are aligned precisely with the North Star, which can easily be identified on a clear night using the sundial.
The main south facing or “polar dial” shows the time throughout the year and is set to tell local Venetian time, both in summer and winter. The dial beneath is only touched by the sun between the Autumn and the Spring Equinoxes, when the sun appears low in the sky. Conversely, the sun will not shine on the sloping dial facing north until the Spring Equinox. This dial will remain active until the Autumn Equinox, when it will once again become dormant.
The cut-away section on the upper part of the dial is of special significance, being dedicated to Peggy Guggenheim. It is engraved with lines representing the dates of her birth and death. On those two days each year, the sun’s shadow will fall precisely along the appropriate marking.
The marble plinth on which the dial sits and the marble paving stones on which the plinth stands are precisely aligned to true north. When the shadow of the vertical edge of the plinth falls along the line of the paving stones, the sun will have reached its highest point in the day. The garden itself will have become a sundial. It will be exactly mid-day local Venetian time.
Because the earth is tilted, has a slight wobble and circumnavigates the sun in an ellipse, not in a circle, the length of solar days vary according to the season. Man-made “Mean Time” however does not vary, being twelve equal hours of day and night, regardless of the time of year.
To set a clock or watch to time using the sundial, it is therefore necessary to know the difference between solar, or “God’s Time”, and man-made “Mean Time” on any given day. Joanna Migdal has engraved a circular bronze plaque, displayed on the wall not far from the sundial, which gives this difference in graphic form for every day of the year, taking into account local longitude correction.
The 4orty 5ive Sundial is a gift of Alick Campbell of Lochnell, of the artist Joanna Migdal, with support from Sir George White Bt., and from Penny Richardson Borda in honor of Philip Rylands.
|Credit line||Solomon R. Guggenheim Foundation. Gift of Alick Campbell of Lochnell, of the artist Joanna Migdal, with support from Sir George White Bt., and from Penny Richardson Borda in honor of Philip Rylands|