Mart van Duijn
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After the publication of the
article ‘Salomon Coster, the clockmaker of Christiaan Huygens’ the authors
decided to have the enigmatic Figura horologij mei edita anno 1657-drawing
examined by the Leiden University Libraries. The investigation revealed that the
Figura drawing had been made for the printing of the image in Huygens’s
Horologium, published in 1658.
By BH and RM
2018 we had planned to study the correspondence of Christiaan Huygens at Leiden
University Libraries. Already during our first visit to the reading room we came
across two interesting finds, a drawing of an unknown clock dial and a drawing
of the profile of a pendulum clock movement. The latter drawing is darkly
coloured and drawn in ink on one side (Fig. 1) and traced in pencil on the other
(Fig. 2). This drawing is now known as the Figura horologij mei edita anno
1657-drawing (hereafter Figura drawing). We immediately associated both the dial
drawing and the Figura drawing with Huygens’s Horologium image of 1658 (Fig. 3),(1
the first pendulum clock publication of Christiaan Huygens. After researching
the Oeuvre Complètes,(2
literature and publications, we noticed that neither of the drawings had been
depicted previously. Joella Yoder catalogued and briefly described both drawings
in her book A Catalogue of the Manuscripts of Christiaan Huygens,(3
but neither is
depicted there. The Figura drawing in particular intrigued us because of its
similarity to the Horologium clock, the handwritten text and the possibility of
new insights into the early development of the pendulum clock.
discovering all kinds of other documents, we decided to make a publication about
the invention and manufacture of the early pendulum clock during the period 1657
– September 1658.(4
For us it was a necessity to work as much as possible with
primary sources from the seventeenth century. The use of secondary sources from
the eighteenth century and later, we considered as highly undesirable because of
the strongly diminishing reliability of information. The relevance of later
secondary sources is in our view only suitable when it unquestionably supports
an explicit primary source.
Prior to the publication, we asked Dr Mart van
Duijn to carry out an initial inspection of the Figura drawing. The results were
included in the aforementioned publication. After our publication, and the
comments published in the next journal issue,(5
we decided that
the Figura drawing needed more and extensive in-depth study. At our request Dr
Mart van Duijn and Drs Jef Schaeps agreed to perform a new extensive in-depth
inspection of the Figura drawing. Their findings are presented in the next
The verso side of Codices Hugeniani, HUG 32 folio 188
(Leiden University Libraries), showing a drawing in ink of the profile
of a pendulum clock with on top right the inscription Figura horologij
mei edita anno 1657 (A drawing of my clock made known in the year 1657).
The dark surface is caused by the etching ground of the copperplate
which was used to print the Horologium image.
The recto side of Codices Hugeniani, HUG 32 folio 188
(Leiden University Libraries), showing the mirrored drawing in pencil
which is traced from the ink Figura drawing on the verso side (see Fig
1.). On the top left the inscription Tabula haec Aeri incisa reperitur
in Hugenii Horologio (This drawing, incised in copper, is found in
Click to enlarge
THE RESEARCH OF THE FIGURA
By MvD and JS
32, fol. 188, is part of Huygens’s extensive archives kept at Leiden
University Libraries, mostly containing his scientific workbooks and
correspondence. HUG 32 is described by Yoder as a collection of loose
sheets of various sizes and dates, called Portefeuille Varia  by the editors of the
Complètes. Most of the material was written by Christiaan’s primary
heir, Constantijn Huygens Lz; only ff. 168–192 are in Christiaan’s hand.
Unlike most of the material in Huygens’s archives, which was bequeathed
to the library after Huygens’s death in 1695, HUG 32 was gathered by the
lawyer and collector Jean Theodore Royer (1737–1807) and willed to the
library in 1809.(6
Image of the Horologium (1658) clock from the collection
of the Leiden University Libraries (539 F 29). This copy belonged to
Isaac Vossius, who received Horologium directly from Christiaan Huygens.
The sheet in question measures 290 by 172 mm, with one of the lower
corners torn off, and has a modern foliation in pencil. The verso side
has the Figura drawing in ink, with letters indicating the
different parts of the pendulum clock. The upper right corner has a
barely legible inscription, by Huygens himself: Figura horologij mei edita anno 1657
(A drawing of my clock made known in the year 1657). Yoder was unable to
decipher the first word, but Ben Hordijk and Rob Memel managed to
publish a complete and convincing transcription in their article (see
note 4). The ink drawing is covered with a greyish residue of etching
ground, resulting in a somewhat darkened image. This darkening is not
the result of the erasure of another or earlier drawing, as has been
suggested. The recto side of fol. 188, bearing the stamp of Leiden
University Libraries, has the Figura drawing in graphite (pencil). The
upper left corner has a seventeenth-century inscription: Tabula haec
Aeri incisa reperitur in Hugenii Horologio
(This drawing, incised in copper, is found in Huygens’s Horologium). The
drawings on both sides exactly align, probably the result of the ink
drawing on the verso side being traced in pencil on the recto side.
Although the modern foliation might suggest otherwise, the image in ink
was done first, followed by the tracing in
End of this section, click here to
Hugenii a Zulichem Const. F. Horologium (The Hague, Adriaan
Oeuvres Complètes de Christiaan Huygens publiées par la Société
Hollandaise des Sciences (The Hague: Martinus Nijhoff, 22 vols,
1888–1950); hereafter: OC.
Joella G. Yoder, Catalogue of the Manuscripts of Christiaan
Huygens Including a Concordance With His Oeuvres Complètes.
History of Science and Medicine Library, Volume 35
(Leiden-Boston: Brill, 2013).
‘Salomon Coster, the clockmaker of Christiaan Huygens. The
production and development of the first pendulum clocks in the
period 1657 – September 1658’, Antiquarian Horology 42/3
(September 2021), 323-344.
Letters to the Editor in Antiquarian Horology 42/4, 576-580.
Yoder, Catalogue of the Manuscripts of Christiaan Huygens, p.
With ‘Aeri’ instead of ‘iteri’ as transcribed by Yoder. Thanks
to Jos van Heel (former curator old collection Museum Meermanno
For a detailed description of the process see Ad Stijnman,
Engraving and etching, 1400– 2000: a history of the development
of manual intaglio printmaking processes (London/Houten, 2012),
pp. 155– 157.
Studied copy: Leiden, University Library, 539 F 22 (copy of
Yoder, Catalogue of the Manuscripts of Christiaan Huygens, p.
A construction to minimize the amplitude of the pendulum by
adding a pinion and a wheel, in the Figura/Horologium drawing
marked O and P. Huygens also experimented with non-cycloid arcs
in the early phase. Both the OP construction and the non-cycloid
arcs no longer exist with the invention of the cycloid shape at
the end of 1659.
Codices Hugeniani, HUG 45 letter Huygens to Kechelius June 1657
(OC II, letter no. 392) and Codices Hugeniani, HUG 45 letter
Huygens to Chapelain 28 March 1658 (OC II, no. 477).
Christiani Hugenii Zulichemii Const. F., Horologium
oscillatorium sive de motu pendulorum ad horologia aptato
demonstrationes geometricae (Paris, F. Muguet, 1673).
See, among others, in La veuve Estienne & Fils, Le Spectacle de
la Nature (1756) and Benjamin Martin, A new and comprehensive
system of mathematical institutions, agreeable to the present
state of the Newtonian mathesis (1764).
Dr. Mart van Duijn (MvD) is Curator of
Post-Medieval Western Manuscripts and Archives at Leiden University
Drs. Jef Schaeps (JS) is Curator of
Prints and Drawings at Leiden University Libraries.
Ben Hordijk (BH)
is the former chairman of the Museum and
Archive of Horology and founding member of the Horological
Rob Memel BA (RM) Rob
Memel is a restorer of early clocks and complicated pendulerie with
an interest in seventeenth-century Horological archive research.
Address for correspondence: firstname.lastname@example.org
The residue of
etching ground seems to point to a very common technique, used for
transferring images to a copper printing plate. In general this process
entails placing a drawing on a copperplate covered with etching ground
(wax containing a pigment such as sooth or graphite), after which the
drawing was retraced with a sharp object, indenting the etching ground.
To avoid a mirrored reproduction of the design, a preceding step was
necessary in which the drawing was first traced on the back of the
sheet. This is what has been done with Huygens’s Figura drawing in ink,
with the back of the drawing now being identified as the recto side. The
indentations are still visible (Fig. 4).
Detailed image of the recto Tabula drawing (see
Fig 2). The indentations are usually on the pencil line, which
makes it difficult to show in an image. Here the indentations
are just beside the pencil line. Between the yellow lines is
the traced pencil line. Between the red lines the indentations
to make a transfer onto the copper plate.
After the drawing had been
transferred onto the plate, this was etched in order to produce a
A drawing by Huygens used to transfer a design to a printing plate is of
the utmost rarity. No other example is known from Huygens’s archives
kept in Leiden. This kind of drawings usually perished in the transfer
Comparing the Figura drawing to the image in Huygens’s
Horologium, as is suggested in the anonymous inscription on the recto
side, reveals the fact that the drawing and the printed image are
identical, with the exception of the letters (Latin and Greek), that
were probably added to the plate separately
Yoder refers to the ink drawing as an exact copy of the Figure used in
while in fact the ink drawing on HUG 32, fol.
188 verso, is the original design used to create the printed image of
Huygens’s pendulum clock in Horologium (1658) (Fig. 5).
From left to right the process of
the Figura ink drawing, the traced mirrored Tabula
pencil drawing to the final image in Horologium
before his death in 1695, Huygens donated a significant part of his
to the University Library in Leiden. After 1800 this legacy was further
enriched with family-owned manuscripts and letters. The personal archive
of Christiaan Huygens has been brought together in the Leiden University
Library in the so-called Codices Hugeniani and is digitally available.
These Codices Hugeniani are collected in fifty-two volumes and contain
notes and folders with loose texts in the fields of astronomy,
mechanics, mathematics and music, as well as annotated books and sent /
received correspondence. At the top of the pages of the original letters
of Huygens the editors of Oeuvres Complètes added in pencil their own
method of numbering the letters, which matches the letter numbers in Oeuvres Complètes as contained therein. For clarification and
traceability we added the OC numbering in the footnotes as well.
order to gain a better understanding of the following, it is important
to know that before Huygens sent a letter to one of his contacts, he
first wrote a draft or working copy. The primary purpose of this working
copy was to organize his thoughts and make improvements when necessary.
Once this was to his liking, Huygens wrote the letter in a final version
to send it out. He kept the working copy for himself so that he could
reread it later. The working copies of Huygens’s outgoing correspondence
are thus located in Leiden, while the same letter in the final version
may be kept elsewhere, for instance in Paris.
The original documents
of the University Library in Leiden show that Huygens consistently and
frequently used his working copies of letters as scrap paper for notes,
sketches and points of interest. Especially the back, but also the
margin of the copy was used (Fig. 1). These notes are not always
included in Oeuvres Complètes and can provide new presumptive evidence
to the history of the development of the pendulum clock.
AND THE DEPICTED CLOCK
By BH and RM
Huygens made many sketches of clocks and parts of clocks that are
interesting for closer research. Unfortunately most of these sketches
are undated which makes it difficult to date them in a specific
year/month. Drawings by Huygens, like the Figura drawing, are extremely
rare certainly when it concerns the original drawing which was used as a
transfer on a copper plate for Huygens’s Horologium. Because of the text
Figura horologij mei edita anno 1657 on the verso side in Huygens’s own
handwriting, it is certain that the design of the clock, including the
vertical escapement wheel, the absence of the arches, the Huygens
endless cord and the central seconds hand existed at the latest in
December 1657. Also, the handwritten text on the pencil tracing clearly
indicates that Huygens used a copper plate for his Horologium
publication. Unfortunately, Huygens did not add a specific month to his
text. December 1657 is therefore the most cautious estimate, but in
theory it could also be January 1657. We consider the latter less likely
since the first design of Huygens’s clock was a pendulum linked to a
That the Figura movement could have been the movement from Coster’s
patent application is an option, but we would like to emphasize that
there is no evidence for this. It is even questionable whether a drawing
was included in the patent application at all, since the existence and
ultimate proof of such a drawing is completely lacking.
in Horologium and Horologium Oscillatorium
By BH and RM
impossible to say with certainty when Huygens made the Figura drawing.
As the clock as such already existed in 1657, it is a promising
possibility that the drawing was also made in 1657. We know that Huygens
started writing Horologium by the end of 1657 and that the process from
the delivery of a manuscript to a printed copy could take months in the
seventeenth century. Nevertheless, we can establish that the Figura
drawing is the earliest existing accurate drawing of Huygens’s pendulum
In 1673, Huygens published Horologium Oscillatorium,(13
his second publication on clocks. This publication also contains an
image of a clock (Fig. 6).
Image of the Horologium
Oscillatorium (1673) clock from Huygens’ own copy
which is part of the collection of the Leiden
University Libraries (755 A 5).
The clock in this image is equipped with the
cycloidal arcs that Huygens writes about extensively. Huygens invented
the cycloidal arcs by the end of 1659, and clocks (almost) identical to
this image were unmistakably manufactured from December 1659 onwards.
Particularly in the eighteenth century, publications were issued in
which the clock image from Horologium Oscillatorium was used as a basis,
and the author in question produced his own woodcut or engraving
That Horologium and
Horologium Oscillatorium were regarded by Huygens as his earliest two
treatises on clocks is obvious. In Horologium Oscillatorium Huygens
makes two clear references to his earlier and first publication
Horologium. In his opening sentence in typical muddled
seventeenth-century language, he writes:
It is the sixteenth year since
we published a pamphlet about clocks, then recently invented by us.
year Huygens means the year 1658, where 1658
is the first year and 1673 the sixteenth year.
This translation and accompanying explanations are
supported by experts of Leiden University
Libraries. Some authors misinterpret this sentence
and mistranslate it as it is sixteen years ago,
resulting in the year 1657 which is clearly
incorrect. In Horologium Oscillatorium Huygens reconfirms the
year 1658 in a number of sentences after the opening sentence:
Sixteen years ago [1657, BH/RM], when neither in words nor in writings
had anyone mentioned clocks of this kind, or in general any rumor was
spread (I am talking about the use of the single pendulum employed in
timepieces, for nobody will dispute the addition of the cycloid), I
invented its construction by my own thinking and had it realized. In the
following year [1658, BH/RM], which was the fifty-eighth of this
century, I published the image of the automaton and the description;
copies of both the movement itself and the booklet I sent in all
In contrast to the sixteenth year
in his opening
sentence, Huygens does write here sixteen years ago which is
1657. In that year Huygens indeed ...invented and had the construction....
realized, in which the first clocks were manufactured by Salomon
In the year after, which was the fifty-eighth of this
century, I published the image of the automaton and the description.
Here Huygens clearly refers to the
Horologium image being the image of
the automaton followed by the description being Horologium, Huygens’s
first publication in the following year 1658.
(This article is subject
to ongoing revisions.)
First published by The Antiquarian Horological
Society in: Antiquarian Horology, Number two, Volume
forty-three, June 2022. p.208-213.
Huygens' Œuvres Complètes.
Chr. Huygens Horologium 1658.