Gardening with ideas
Orbital movement of the earth causes the gradual and predictable travel of a shadow across the face of a sundial. Each sundial must be designed for an exact location, otherwise it will only reveal the dialler’s ignorance (Figure 1). Adaptation to a precise location is a good principle in all garden design. The length of the shadow cast by a sundial’s gnomon depends on the time of year, the latitude of the dial, and the position of the earth on its daily rotation. No two identical dials, in different gardens, will cast shadows in the same position at the same time. Sunlight itself is pro duced by the conversion of hydrogen to helium and takes 8 minutes to travel the 149.6 million kilometres from sun to earth. It is little wonder that dials induce contemplation. They were placed on church towers, because ‘time is a sacred thing’. When mechanical clocks became available, the demand for dials increased: they were needed to set the clocks. When other ways of setting clocks became available, many old dials were moved into vicarage gardens.