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Epact Launched

Autumn, 1998

FOR several years four European museums with collections of medieval and Renaissance scientific instruments have been collaborating on a combined electronic database. The four museums in question are the Museum of the History of Science in Oxford, the Museum of the History of Science in Florence, the British Museum, and the Museum Boerhaave in Leiden. The project was given financial support by the European Commission and the result – the ‘Epact’ catalogue – is now available from a computer in each institution.

The purpose of Epact is to give visitors to each museum the chance to study objects more closely than is possible in the galleries, along with access to more detailed information than it is practicable to present in a display case. As well as objects in store, distant collections are also accessible, allowing a far greater degree of cross-comparison than could otherwise be done by more conventional means.

All European instruments from each museum by makers who were active before 1600 have been included in Epact. They number astrolabes, armillary spheres, sundials, quadrants, nocturnals, compendia, surveying instruments, and so on. Examples range from ordinary instruments for everyday use to more extravagant and often lavish pieces destined for the cabinets of princes.

Each instrument is presented via a large, high-resolution photograph, with accompanying texts. The texts give systematic information about the instrument, such as its maker, place, date and dimensions, as well as an overview of its most significant characteristics. At a further level, detailed information and technical descriptions are available, the aim being not only to provide a resource that is accessible to the general museum visitor but one that is also of value to the scholar. Perhaps the most powerful investigative facility offered is the ability to enlarge the images: this is possible to such an extent that it is easy to make out the minutiae of the inscriptions and the finest divisions of the scales on most instruments.

A range of search tools allows users to find their own route through the entries. There are also extensive links to supporting material about makers, places and technical terms, along with an overview of practical mathematics. The database thus offers material for exploration and discovery, together with help in understanding each instrument’s content and context.

The name ‘Epact’ may, if desired, be expanded to ‘European pact’, emphasizing the accord on which it is built. However, it has principally been chosen for the project name because of its resonance with the instruments of the time. In its technical meaning, the ‘epact’ is a number equal to the age of the moon on the first day of the year. This number was of considerable importance in the period as it was necessary for determining the date of Easter, Easter Sunday being the first Sunday after the first full moon in the year (the old year, that is, which began on the 21st March).

For this reason, tables of epacts are found on many instruments, as well as, to this day, in liturgical texts such as the Book of Common Prayer. The name Epact itself thus provides a timely reminder that the instruments and the science they represented existed not in isolation but as an integral part of the culture of their age.