Image 1. Sundial (1581), main quadrangle, Corpus Christi College, Oxford; looking northeast. Photograph by Andrew Shiva,15 April 2014. Source: Wikimedia. License: CC 3.0.
Image 2. 3D Image by Jamie Cameron (Oxford Internet Institute, University of Oxford), 14 May 2016. License: CC 4.0.
Image 3. Detail of Corpus sundial, south and west faces. Photograph by Howard Hotson, 14 June 2017, 11:00 a.m. License: CC 4.0.
'In the middle of the courtyard' of Corpus Christi College 'stands a graceful stone pillar on which are different kinds of sundials and a calendarium perpetuum,' Thus wrote Zacharias Conrad von Uffenbach when visiting Oxford in 1710,* and no one who has entered Corpus since can fail to have noticed it.
The column was erected in 1581 on a design by Charles Turnbull, author of a Treatise on the Use of the Celestial Globe (1573). It consists of a rectangular base, a column cylindrical above and octagonal beneath, surmounted by a rectangular block of stone capped by a pyramid, and on top of them all a pelican standing upon an armillary sphere. Although classical influences are evident, this column does not conform to any of the five classical orders.
The four faces of the rectangular block are partly covered by four coats of arms carved in relief: to the south, the arms of Richard Fox (Bishop of Winchester and the founder of the College), to the west those of Hugh Oldham (Bishop of Exeter, patron and benefactor of the College), to the north those of the University of Oxford, and to the east those of the Tudor monarchy.
Below each coat of arms, a dial is engraved on the face of the stone. The lower part of the scrollwork frame around each shield acts as a gnomon to the dial face engraved below it. In layman's terms, at the very centre of the college he founded, the passage of time is recorded by the shadow cast by the founder's coat of arms (Image 4). Turnbull's sundial is therefore an elegant device, combining a permanent memorial to the founder, a practical timepiece, and a virtuoso display of mathematical ingenuity in a manner which particularly delighted von Uffenbach.*
Even more important is the work's religious symbolism. According to medieval bestiary lore, the pelican was supposed to peck its own breast to feed its chicks with its blood. This practice of selfless martyrdom was interpreted as a symbol of the 'corpus Christi', that is, of the body and blood of Christ offered to the faithful in the sacrifice of the Mass. The pelican pecking its breast is found on the arms of Bishop Fox himself (see Image 3) and on the crozier which he gifted to the college. It was thus his natural choice as symbol for Corpus Christi College itself. But the Corpus pelican, instead of feeding its chicks, stands atop an armillary sphere. At one level, the sphere is a model of the physical cosmos redeemed by the body and blood of Christ at his first Advent and destined to be perfected at the end of time at his Second. At another level, the sphere represents the passage of time: it models the movements of the heavenly bodies which cast their shadows across the face of these dials, marking out times and seasons in the terrestrial world from the beginning to the end of time. The Corpus sundial therefore represents a fusion of theology, cosmology, eschatology, natural history, astronomy, applied mathematics, sculpture, and architecture which is both unique and utterly characteristic of its time. Its place at the centre of this main college quadrangle likewise expresses the centrality of this kind of fusion to Oxford academic life in this period.
On the cornice above the shields are four College mottos: ‘1581 Est deo gratia’ (south), ‘Gratia dei mecum’ (west), ‘Est reposita justitiae corona’ (north), and ‘Posui deum adjutorum meum’ (east).
Four further dials are carved into the four sloping faces of the pyramidal cap. A ninth dial is found on the cylindrical shaft,** with a perpetual calendar engraved below it. Nearer the base is another motto, Horas omnes complector, which an inscription suggests was probably added in 1605.
A scale of degrees is marked below the gnomon on the column. This is indicated by an inscription on the octagonal base stating that ‘When Phoebus [Mercury, the morning star] or the moon touch the midday mark the style will show you the space which you will say there is between it (Phoebus or the moon) and the zenith, the poles, and the horizon’.
A replica of this sundial, carved in England of Portland stone, stands in Princeton University. It was given in 1907 by Sir William Mather 'to symbolize the connection not only between Oxford and Princeton, but between Great Britain and America.'
* Oxford in 1710, ed. and trans. Quarrell and Quarrel, p. 33: 'High up on the column are various armorial bearings, ... and it is this that is so remarkably well conceived: that the hours are shown by the shadows of the projecting ornamentations of the escutcheons instead of by pointers.'
** Robert Plot attributed the cylindrical dial to Robert Heggs (sic) and noted that all the hour circles except the meridian circles are ellipses.
Credits: Howard Hotson (December 2016), drawing technical details from R. T. Gunther, Early Science in Oxford, vol I, pt 2: Mathematics (Oxford, 1923), pp. 106-8.