‘Old Humfric Cole’ was the first English-born instrument maker

of Elizabethan England and the foremost practitioner of the

London scientific instrument trade. Twenty-six of his

instruments have survived, six of which are now in the British

Museum. One, device number 12 of Cole’s known pieces and

signed by him in c1570, a combined nocturnal and tide

predictor, is the inspiration for a modern reproduction.

This article gives an insight into the remarkable career and

craftsmanship of Humphrey Cole, as he is better known;

describes the of use of the nocturnal; and briefly explores the

process of re-making early scientific instruments.

Cole (c1530–1591) was active at a time when England’s wealth

was greatly increasing and the need for accurate measurement

was being felt. He was by no means an isolated figure, and a

group of makers appeared nearly simultaneously in late

sixteenth-century Elizabethan England. He is thought to have

come from Yorkshire, and was employed in the Royal Mint at

the Tower of London, in the office of Sinker (die maker). This

post allowed him to perfect his skills and employ them on the

instruments he made, helping to make his name and augment

his income. Cole also had a number of commissions, including

a map for Richard Jugge (1547–1577), printer and publisher of

Bibles, to illustrate the 1572 edition of the Bishops’ Bible.

Another printing commission undertaken by Cole came from

Thomas Digges, who republished his father’s A Prognostication

of Right Good Effect, London, 1576, to which he added his own

A Perfit Description of the Caelestiall Orbes., the first

discussion in English of the Copernican world system.

The heavens were no longer thought of as bounded by the

sphere of the fixed stars. On the contrary, the stars stretched

out to infinity. A diagram to illustrate this novel view was printed,

and Humphrey Cole has been identified as its engraver.

He was also knowledgeable about mining and minerals and

was selected to supply and repair (after each trip) all the

instruments for the ‘Frobisher Voyages’, early attempts to

discover the Northwest passage to India and Cathay, China.

These instruments included: a great globe of metal, an armillary

sphere (celestial globe), an early

theodolite, a universal dial, an

astronomical dial to establish the

time by the sun’s altitude at a

particular

latitude,

and

an

astrolabe. He was paid £7 11s.

Further Humphrey Cole devices

cover the whole range of

mathematical instruments of the

day; sundials and nocturnals for

telling the time by day and night,

astrolabes, and a ‘universal

instrument’ for the same purpose,

and additionally for measuring the

positions of heavenly bodies.

Horologium noctis is the Latin

name of the instrument known in

English as a nocturlabe, or

nocturnal. From the moment of

sunset, sundials are of no use,

and for a long time man

depended on stellar observation

to tell the time by night. It was

known that certain boreal constellations rotated around the Pole

Star about once per day, as if a giant clock hand were keeping

time around the celestial sphere. Observers began to record

the positions of the most significant stars visible to the northern

hemisphere at different times during the night and over the

course of the seasons. The origin of the nocturnal astrolabe,

however, is unclear.

One legend says that Raimund Lull invented the nocturnal to

administer doses of medicine to patients during the night. This

is the concept that gave birth to the nocturnal as we now know

it, the instrument first appearing at the beginning of the 16th

century. It began to disappear in the 18th century, coincident

with the proliferation of accurate mechanical clocks and

watches.

Whilst the astrolabe can be used to determine the solar hour at

night directly using any star found in the firmament, the

nocturnal, being simpler, can only be used on those stars that

are circumpolar. A star meets this requirement when its

declination (height above the equator) is greater than its co-

latitude. In the 16th century, navigators from the Mediterranean

area chose circumpolar stars by which to tell the time. In

Mediterranean latitudes three stars meet this test: Kochab ß of

Ursa Minor, also known as the Little Bear or Little Dipper,

Dubhe α of the constellation Ursa Major, and Shedir α of

Cassiopeia.

When Kochab ß is used, the star α of the same constellation is

the Pole Star (the one to be sighted through the central aperture

of the instrument). Kochab ß is preferred because of its very

high declination, +74° 09’, allowing it to be used in latitudes as

low as the Canaries, 28° 06’N, a fundamental concern for

seafarers. At this parallel the other two stars, because of their

lower declinations, cannot be used.

There are versions of the nocturnal that use two or all three of

the major stars, but this one by Cole is designed only for

Kochab ß. As it is visible from so much of the Northern

hemisphere, the absence of indicators for other stars is no great

disadvantage. The operation is very simple. The main plate,

sometimes called the mater, or mother, is marked with the

months and dates of a full year, and often with a zodiac scale

too. Each of the twelve zodiacal constellations represents 30º

of the ecliptic, and it is generally a very efficient co-ordinate

system. On the edge is a handle, which in this case is meant

Leonard Honey looks at Humphrey Cole - his instruments and their reproduction

to be oriented vertically

downwards.

Concentric with the main

plate is another, smaller,

disc, pivoted upon a

pierced rivet. The disc is

marked 1–12 twice along

its edge. On Cole’s

instrument, the numbers

run anti-clockwise, so the

time can be read directly

off it, but the diagram

above shows the figures

running the other way

round, meaning the time

has to be derived by

subtracting the indication

from 12. The hours, and

often the half-hours, are

marked with prominent

teeth, so that the operator

could feel the time at night.

A further vital feature is the index, marked in this case by a

smiling sun, and in the drawing by fleurs-de-lis. On more

complex instruments, more indices are provided, inscribed with

the names of the stars they are designed to measure.

Also pivoted at the centre is a movable straight index, the

alidade, the key edge of which lines up with the centre of the

instrument. The alidade must, of course, protrude well beyond

the edge of the main disc. In use, the observer chooses which

star he wishes to sight, and sets the appropriate index on the

inner disc to correspond with the current date (in the case of

Cole’s nocturnal there is only one, as has been stated before,

for Kochab ß). The instrument is held up by the handle, and,

while sighting the Pole Star through its centre, the alidade is

swung round to intersect with the chosen star. The time is then

read off the smaller disc.

Such an instrument can be used in any latitude, and remains

operationally accurate for many years, as the variation in direct

ascension varies very little over the centuries.

The reverse of Cole’s nocturnal is a device used to determine

the time of high tide, based on the age of the moon.

The main plate has three zones. The outer is divided into 360º

in 1° intervals, the middle into twice 12 hours, and the inner into

32 compass directions. Within this is a volvelle, or rotating ring,

with a small pointer, and divided into 30 days. This is meant to

represent the age of the moon, but as the lunar cycle is

markedly different to this, the limited usefulness of the

instrument becomes apparent. When considered in conjunction

with a timekeeper that displays the time in ‘quantum leaps’ of

about half an hour, we can begin to appreciate the problems

facing navigators in the late middle ages. The centre of the

device has a lunar volvelle, with an aperture to visually

represent the moon’s age, and a large pointer, and is engraved

with symbols representing the four quarters of the age of the

moon.

The tides, with their constantly changing levels, greatly affect

navigation due to the energy generated by the immense

quantity of water in motion, and its effect on submarine

currents. Moon and Sun both exert gravitational attraction over

water on Earth, the Moon’s effect being more obvious because

of its proximity to the Earth. The change of the water level is

produced about every 6 hours, so that in one day the water

level will rise twice and fall twice. Although, astronomically, the

high and low tides are related to the position of the Moon, there

is in fact a difference between the time that the Moon passes

over a given place on the Earth and the rise or fall of the water

level at that place; this difference in time is called the

‘establishment of the port’ and is defined as the interval

between the passage of the Moon and the high tide over the

local meridian.

Spring tides, happening at the full moon and new moon,

produce the greatest range in height between high and low

water; this is because of the syzygy, where the Moon, Sun, and

Earth are aligned in space.

At neap tides, in the first quarter and last quarter of the Moon,

the Moon and Sun form a right angle with the Earth, the

attraction of the Moon is partly counteracted by that of the Sun,

and the difference between high and low tide is at its least. It is

therefore clear that a knowledge of the moon’s age is vital to

mariners, especially those active in Humphrey Cole’s era.

A critical point with the use of a tide predictor such as this is that

it can only determine the time of the passage of the moon over

a certain point. In order to discover the actual time of high tide,

a separate chart recording the ‘establishment of the port’ must

be consulted, in much the same way that the equation of time

must be known before a sundial can be put to good use.

The primary technical consideration is, of course, to make the

instruments work as they were originally intended. Once it has

been decided which instrument is likely to be of commercial

interest, and to capture the

imagination, the engineering

process

can

begin.

Engineers, mathematicians

and astronomers have all

been employed to perform

the required calculations, in

order, for example, to ensure

that a given instrument will

work at a certain new

latitude. The skills of graphic

designers, illustrators and

modelmakers

are also

harnessed to ensure that the

final moulds we make

represent

the

piece

accurately.

Sometimes an item is

available to be examined, in

which case photos or

drawings can be obtained. In

the case of the Humphery

Cole instrument described

here, plans were based on

pictures from a book.

Missing or unclear parts

require further research and

comparison with similar

items, extrapolating the information where necessary, so that a

working instrument can be made.

In nearly every case it is impossible to effectively make the

reproduction instrument in the original material. These early

devices were made of brass, copper, and bronze, and would be

prohibitively expensive to cast today: zinc and aluminium alloys

are used instead, with gold plating to improve the appearance.

Such a reproduction takes considerable time, especially the

research and the correction of errors after the prototypes are

made. About six months mathematical and historical research

is required, including finding and making drawings. Once all the

technical aspects are resolved, master plans are drawn in 3D

using

‘Autocad’.

Prototypes

for

the

casting process are then

made, which takes up to

a month.

Then the silicone moulds

are made, from which

are pulled about ten

proofs. At this point, if

anything needs to be

corrected, the whole

month’s process could

be repeated. Once all

the details are settled

and deemed to be

correct, the development

of the steel mould is

begun, followed by an

initial production run of

250 pieces. The presen-

tation boxes and the

multi-language instruct-

ions. For an instrument

like the astrolabe the development process will take a year’s

enjoyable work! It is no wonder that masters like Cole without

access to CAD, silicone or modern production techniques

were so very highly regarded.

Silke Ackermann (ed.), Humphrey Cole: Mint, Measurement

and Maps in Elizabethan England (London: British Museum

Occasional Paper no. 126, 1998).

Gerard L’E Turner, Elizabethan Instrument Makers. The Origins

of the London Trade in Precision Instrument Making (Oxford:

OUP, 2000).

R T Gunther, ‘The Great Astrolabe and other Scientific

Instruments of Humphrey Cole’, Archaeologia, 76 (1927), 293.

F.A.B. Ward, A Catalogue of European Scientific Instruments in

Museum (London, The British Museum Press, 1981), p. 74 f.,

no. 208.

Reproductions by Hemisferium www.hemisferium.net