.The Abbey Gardens Sundial
Many people will know the pillar sundial and planter in the Abbey Gardens. Some may know that it was originally designed as a drinking fountain and donated to the town in 1869 by the third Marquess of Bristol. It started life in the Traverse, near the Corn Exchange and opposite the Nutshell pub, until it was moved to its present location in 1939 and converted to a flower planter. But very few people will know that the sundial is of international importance and shows that Bury St Edmunds led the way in its timekeeping and advanced mathematics!
The limestone block which forms the sundial is now rather eroded and, being quite high off the ground, it is difficult to read the engraved details. The actual sundial is on the south-facing side. With its bronze gnomon, it is quite neatly designed and shows local solar time, as most sundials do. The east face has a quotation from one of Horace’s Odes (IV.7): “MONET ANNUS ET ALMUM QUAE RAPIT HORA DIEM” which can be translated as ‘The year and the hour that steal the nourishing day away, warn you …’. The Ode is about the passing of the seasons and reminds the reader of their mortality.
It is the west face, though, which makes the dial truely unique. Across the top it reads “For Greenwich Mean Time” and below that is a graph which shows how many minutes to add or subtract from the sundial reading to get GMT. The Act of Parliament by which GMT became the legal time for the country was not passed until 1880 and many towns – Oxford in particular – continued to use their local time for many years afterwards so Bury St Edmunds was ahead of the game. The sundial is thought to be the earliest in the country designed for GMT.
Fig. 2. The engraved graph on the west face of the sundial
The graph conveys the two corrections between solar and mean time (due to the longitude of BStE east of Greenwich, and to allow for the elliptical orbit of the Earth around the Sun) in a particularly elegant and subtle way. It is reconstructed in the drawing above. Its shape is due to a special piece of mathematics developed by William Whewell, Master of Trinity College Cambridge, in the 1840s. This fact only came to light in 2005 when it was discussed in the journal of the North American Sundial Society: it is now known worldwide as “the Bury St Edmunds curve”!
The reason why the sundial has such a unique feature is that it was designed by the architect Francis Cranmer Penrose FRS (1817-1903). Penrose was a great Victorian polymath, rising to be the President of the Royal Institute of British Architects and inheritor of Sir Christopher Wren’s post as Surveyor for St Paul’s Cathedral. As well as being an architect, he was a classical archaeologist who made pioneering measurements of the Parthenon, and an astronomer who published articles on, for example, graphical methods of predicting the paths of comets and occultations of Saturn.
Penrose’s interest in mathematics had begun when he studied that subject at Magdalene College, Cambridge, where he would have been exposed to Whewell’s new theories. Whilst he was there, he also found time to row for Cambridge against Oxford and to invent the system of scoring the ‘bumps’ on the Cam.
The need to restore the Abbey Gardens sundial is now pressing, before its features are lost. It has recently been assessed by conservators and a report produced.
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