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New Acquisition: an English Diptych

Autumn, 1996

The Museum has recently acquired, with
the support of the Renaissance Trust and the PRISM fund of the
Museums and Galleries Commission and the Science Museum, a rare
example of an English diptych sundial (Inventory no. 47,973).

The dial is only the second English
example known, the other being in the Horniman Museum, London.
It is unsigned; however, the circular map of England on one leaf
is from a copper plate that can confidently be ascribed to Charles
Whitwell (d. 1611) and it is probably an example of work
from his early period, the last decade of the sixteenth century.

The instrument is octagonal in form
and measures 84 x 62 x 19mm. It is made from ivory, with hinge,
catches, and ring all of silver. The lower leaf holds a magnetic
compass, and the underside of the upper leaf is embellished with
the map of England, 52mm in diameter and displaying the counties
with their boundaries outlined in colour. Inside, both leaves
are decorated in a simple manner with small punches, the indentations
being coloured in red, green or yellow. On the outside the ivory
is entirely without decoration.

The compass on the lower leaf has a
compass rose of paper, printed with sixteen triangular pointers,
and a blued-iron needle, marked ‘N’ and ‘S’ in a gold-coloured
medium. Around the compass well are the hour lines marked with
roman numerals and divided to quarter-hours.

When closed, the two leaves are held
firmly together by a pair of silver catches and pegs. The use
of silver for these fittings is quite contrary to continental
practice for this type of dial.

To use the dial, the leaves would
have been opened with the face containing the map positioned vertically
and held in place at 90° to the lower leaf by a catch at
the back of the hinge. Between the leaves a string gnomon, now
missing, would once have been attached, and it is this that would
have cast a shadow over the hour lines on the lower face, indicating the correct time once the dial had been oriented north-south
by means of the compass.

Where the gnomon met the upper and
lower leaves the number ’52’ is punched, indicating the latitude
at which the dial could be used. A small dial such as this made
for a latitude of 52° would serve for Oxford, London and

Like the Oxford instrument, the dial
in the Horniman collection is also made from ivory, is octagonal
in shape and is quite plain on the outside. It is only slightly
smaller than the Oxford dial and it too carries a map of England
and has a printed compass card, but in neither respect is it identical to the Oxford dial.

The Horniman dial has a silver hour
ring and in contrast to the Oxford example its map and compass
card are not coloured and the magnetic needle is shaped like an
arrow, pointed at North and feathered at South. Also, unlike the
Oxford example, it bears a set of initials – ‘R × G
– which could be those of the dial’s maker or of an owner.

The Oxford and Horniman dials do have
a decorative feature in common: surrounding both the compass and
the map are two concentric circles which are themselves embraced
north and south by circular arcs. A point of difference is that
the lines are single on the Horniman dial, but doubled on the
Oxford dial.

In trying to assign the Oxford dial
a date, maker and place of manufacture, several of its features
are of particular interest: the printing of the compass card,
the shape of the magnetic needle, the appearance of the map and
the characteristics of its engraving.

The compass card or wind-rose on the
Oxford dial is printed with sixteen triangular points, between
which are a further sixteen divisions at the outer rim showing
the thirty-two winds, or points of the compass. The North point
is shown by a fleur-de-lis, and on the rim at the East point is
a small cross. There is no other decoration or any colouring or

Remarkably, there is a second wind-rose
underneath the first which can be made visible by shining a light
through the translucent ivory of the bottom of the dial. Like
the first it has sixteen points. The magnetic north is marked
by a similar fleur-de-lis, but it is placed in the compass box
one point (i.e.11¼°) east of the dial’s meridian line.
Unlike the upper wind-rose, the triangular points seem to be
coloured, in white, black, red, and green.

The magnetic declination at London
in 1580 was 11° 15´ east. It then moved gradually west
becoming zero in 1657. Late Elizabethan dials and magnetic compasses
in compendia have the magnetic north marked on them at one point
to the east, so the evidence given by the concealed card points
to an Elizabethan date for this diptych dial. A person using the
dial in around 1660 presumably placed a new, and plainer, card
over the original one.

As far as the maker of the compass
card is concerned, cards used by Humfrey Cole (d. 1591)
in his astronomical compendia are much more elaborate than either
found in the Oxford dial, having thirty-two ribbon pointers in
a variety of colours, many bearing the name of a wind. The same
pattern is found cut by Augustine Ryther (fl. 1576-1594)
on a plane chart dated 1592 that he produced for Thomas Hood.

A plainer and larger compass card but
of similar design to the Oxford cards can be found on a compendium
by Whitwell (who was apprenticed to Ryther) in the National Maritime
Museum. However, on two compendia dated 1602 and 1606, Whitwell
used a version of the elaborate card of Cole and Ryther. He was
not alone in using different types of card, however, as Elias
Allen (d.1653), who was apprenticed to Whitwell, is also
known to have used both patterns of card.

While the compass cards on the Oxford
diptych dial are smaller than those on the Cole compendia, in
their conception they resemble those found on Whitwell and Allen
compendia. The Horniman dial, likewise, has a card of the same
size which closely resembles both cards on the Oxford dial.

The magnetic needle on the 1606 compendium
by Whitwell is of the same style as that on the Oxford dial, each
arm being an elongated lozenge bearing the letters ‘N’ and ‘S’.
The Oxford needle is, however, at 37 mm in length, some 13mm shorter
than that on the compass of the Whitwell compendium.

It is possible that the Oxford needle
was a replacement provided at the time the new compass card was
fitted in the 1660s. This would, of course, suggest that the Whitwell
compass needle is also a replacement. The needles on the other
compasses mentioned above resemble arrows, and different patterns
of needle, made in blued iron, are to be found on other dials
of the period between 1590 to 1610. All that can be said with
confidence is that the Oxford dial has a needle that is not a
modern replacement.

Both the Oxford dial and the one in
the Horniman Museum have circular maps of England. Both also show
the eastern side of Ireland and a portion of Scotland, are labelled
the same way, have a scale in the Bristol Channel, and have a
compass rose above Norfolk. On the Oxford map the arms of the
three kingdoms are also shown.

The high quality of the engraving of
the map on the Oxford dial is also very apparent. On the Horniman
dial the counties are outlined crudely and are marked with an
initial only; on the Oxford map the counties are better delineated
and the lettering is finer, and their names are abbreviated or
even, in a few cases, given in full.

An example of a map of England within
a circle is to be found in Arthur Hopton’s Speculum topographicum:
or The Topographicall Glasse
which was published in London
in 1611. The map is reproduced on pages two and eighty-six of
the book as well as on the title page, but it is larger than those
on the dials, having a diameter of 83 mm.

The copper-plate cut for the Oxford
map could have been produced some years before the dial was made.
The quality of the engraving points to an engraver with the skill
of Ryther, Whitwell or Allen. It is conceivable that the map was
modelled on a map of England and Wales engraved by Ryther that
was published by Christopher Saxton in 1579. This was the first
printed atlas of the country, and the first uniform national atlas
for any country. Both Ryther’s map and that on the diptych dial
have the sea stippled by the point of a burin, and Ireland, Scotland
and the three seas are all named in the same way.

Ryther is known for engraving playing
cards as well as maps and instruments. His cards, datable to 1574,
each have an outline of a county with a few features and initials
of towns. The top and bottom of each card has information on the
size of the county and its products. There are brief comments,
for example:

SVFFOLKE a ritch & plesaunt
coutrey Aboundinge in cheese, & butter, & store of cloth
and NORFOLKE large,
welthy, & very populous. Full of corne, sheepe, & worsted
commod ities
Such observations seem to anticipate the motto found circumscribing
the map of England on the Oxford dial: ‘OF THESE THINGES FOLLOWINGE,

The map is the part of the diptych
dial that has the most information suggesting a probable maker
and date for the instrument. Many instruments can be dated by
the numbers punched into them, but while the latitude number ’52’
on this instrument is punched, it is not easy to trace because
punches were not generally used by Elizabethan engravers and scarcely
at all by their successors in the seventeenth century (the occasional
exception being their use for the figure zero). Punches are suitable
for ivory and wood, but the use of ivory during the relevant period
is rare and the earliest dated wooden instrument to survive is
a nocturnal of 1637 in a private collection.

However, the map engraver’s hand shows
certain features, and some of these can be picked out on the Oxford
instrument. The only numbers on the map are with the scale, but
they are under one millimetre in height, and therefore have no
diagnostic value. Amongst the uppercase letters the ‘S’ tips over
towards the right, and the bottom bar of the ‘E’ is extended.
In the lower case letters, the ‘p’ has a gap at the top between
the risers, and the ‘r’ has its upper curl distant from the riser.
These, and other characteristics, are all found on examples of
the work of Whitwell, including, for example, on a vertical sundial
already in the Museum’s collection (Inventory no. 52,101).

At the present time, thirty instruments
have been identified as having been made by Whitwell. In addition,
he is known to have engraved maps of Jerusalem, France, Surrey
and Kent, as well as illustrations for books such as William Barlow’s
The Navigators Supply (London, 1597) and Thomas Hood’s
1598 work on the making and use of the sector.

In many of his products, Whitwell had
to engrave very small letters and numbers, and from the variety
of instruments surviving, as well as from the level of the patronage
he received, it is clear that he was the leading engraver of mathematical
instruments between 1590, when he completed his apprenticeship
with Ryther, and 1611, the year in which he died.

The round map is a small commission,
and was probably done in his earlier period, 1590-1600. Of course,
the plate could have produced copies for many years more, so the
date of the manufacture of the dial remains somewhat inexact.
The Horniman dial also has to be included in a dating estimate
because its form suggests that both ivory dials came from the
same maker.

The production of diptych dials with
magnetic compasses was a trade particularly associated with Nuremberg
during the sixteenth and seventeenth centuries. Nuremberg dials
were made in ivory, boxwood and, after 1608, pearwood. Ivory examples
from the 1550s are preserved, but most extant Nuremberg ivory
dials date from the seventeenth century.

Nearly all ivory diptych dials from
Nuremberg are rectangular, with a few oval in form, although the
Harvard University collection of ivory diptych dials contains
three from Nuremberg that are octagonal in form, one dated c.
1620, the other two c.1650. Similar to the dials from Nuremberg
are French ivory magnetic azimuth diptych dials which were made
in Dieppe during the second half of the seventeenth century. Only
a very few are octagonal, however, most being square or rectangular.

Harvard’s collection of diptych dials, which numbers
eighty-two in total, does not include an English example, neither
does the collection of fifty in the Whipple Museum, Cambridge.
Until now, Oxford’s collection of over a hundred and twenty diptych
dials contained no English example either.

Gerard L’E. Turner

Further reading: Penelope Gouk, The
Ivory Sundials of Nuremberg, 1500-1750
(Cambridge, 1988) and
Steven A. Lloyd, Ivory Diptych Sundials, 1570-1750 (Cambridge,
Mass., 1992).