Time travel at the speed of light

A MAJOR part of the instrument holdings at the National Maritime Museum is the collection of portable sundials, the everyday timekeepers used by both rich and poor for three millennia before they were superseded by the watch. This book covers particular periods in the history of the sundials all set within their social and political contexts.

Among the museum’s collection is one of three naviculae vitae dating from the 15th century, found by chance in July 1989 at Sibton Abbey, near Saxmundham in Suffolk with all its parts except for the plumb line and bead having survived and with its marking still very clear, possibly dropped by a rich visitor to the abbey or it may have belonged to the abbot himself. The navicula de Venetiis – little ship of Venice – was one of the most uncommon forms of aristocratic dials produced during the Middle Ages and comes from the shape of the dial, which is in the form of a medieval ship. Peculiar to England, despite its name, the surviving examples appear with the towns and latitudes marked on them providing information about places in England and nowhere else.

The Sibton Abbey dial was intended for an owner given to travel; it has a brass plate in the form of a ship whose hull is topped by a castellated poop and forecastle and a mast. The castellations are not merely for decoration but carry the pinhole sights used for lining the navicula up with the sun… and the the back of the mast includes the latitudes for London, Oxford and Northampton, this last being the rich owner’s home and thus the sundial is a bespoke instrument.

Fascinating stuff by the author, who studied the collections of sundials, nocturnals and horary quadrants at the Royal Observatory, the chapters pick out one or more detailed examples as the focus on a wider field, while the final chapter,
The Sun Eclipsed, includes a few forgeries, including the 20th century fake sundial, inscribed Christophorus Schissler, 1565, bought by the National Maritime Museum and fine in all its detail, only to be identified as a fake as soon as it was compared with other instruments made by Schissler.