Codices Hugeniani Online

Codices Hugeniani Online (COHU) offers the fully digitized archive of Christiaan Huygens (1629 - 1695), held at Leiden University Library. The archive includes notebooks and loose leafs with texts in the field of astronomy, mechanics, mathematics and music, as well as correspondence and annotated books.

 

Huygens was a prominent Dutch mathematician, astronomer and physicist. He published major studies on mechanics and optics, and a pioneer work on games of chance. He is famous for his discovery of the rings of Saturn and its moon Titan, and for inventing the pendulum clock.

 

Shortly before his death in 1695 Huygens bequeathed a large part of his scholarly papers to Leiden University Library. After 1800, the legacy was further enriched by manuscripts and letters from family property, amongst others a large number of letters from Huygens' father Constantijn (1596 - 1687).

 

For over three centuries, many scholars have made the Codices Hugeniani the object of their research. The contents of the archive have been made partly accessible through the well-known Oeuvres complètes (a 19-volume 19th Century reference work). More recently, the Codices Hugeniani were described in detail by Dr. Joella Yoder in her Catalogue of the Manuscripts of Christiaan Huygens (Brill, 2013). With COHU the full archive's contents are now easily accessible for the first time.

 

Features and benefits

 

Sections

COHU is logically organized in the same way as the original archive, i.e. 52 codices as main entrances, enabling an overview of the archive as a whole.

 

Advanced search options

In each codex the scans are offered in smaller groupings ranging from 1 to several dozen folios each. These groupings are all described with detailed metadata. This offers the possibility of an advanced search for specific topics, etc.

 

Rich metadata

For a large part the metadata are taken from Joella Yoder’s catalogue. This is the most authoritative overview and the outcome of 20+ years of hard work. The book contains valuable information about the archive that is not in the Leiden University Library's catalogue.

 

Direct link between famous Oeuvres complètes and archive

The COHU metadata offer a concordance between the physical archive and the Oeuvres complètes.

HUG 1

Book F

 

Book bound in goat parchment, 335 x 210 x 30/ 340 x 220 x 45 mm, titled "F" on the cover by Huygens. Foliated in the upper right corner, including inserts, 179 + 2 ff.; also paginated in lower outer corner; adjunct material, 4 ff. Codex is a workbook covering various topics for the period 1680 to 1688. Part of the original bequest.

 

During the restoration project of 2003-6 an older repair was removed, the book was resewn, and the cover was reinforced before being reattached.

 

HUG 2

Book D

 

Book bound in half leather, 330 x 205 x 35 mm, called "Book D" by Huygens. Foliated in the upper right corner, 219 + 9 ff.; also paginated twice, in lower outer corner and in the upper right corner (odd pages only after p. 102, now crossed out); adjunct material, 4 ff. Codex is a workbook covering various topics for the period 1668 to 1673. Part of the original bequest.

 

The book was restored and rebound some time after the completion of the <i>Oeuvres Complètes</i>, because folios cited by the editors as inserts are now bound in and given <i>bis</i> numbers.

 

HUG 3

Book C

 

Book bound in goat parchment, 320 x 210 x 35/ 327 x 218 x 40 mm, titled "C" on the cover by Huygens. Foliated in the upper right corner, 146 + 1 ff.; also paginated in lower outer corner; adjunct material, 10 ff. Codex is a workbook covering various topics for the period 1663 to 1668. Ff. 137-146 are drafts of letters and the whole section is written upside down, back to front. Part of the original bequest.

 

The spine of the book had been rebuilt in an earlier restoration, and in a 2002 project loose quires at the front of the volume were resewn without dismantling the binding, in the hopes of minimizing intrusions. However, the binding proved too tight, and during the restoration project of 2003-6, after more extensive repairs of the papers, a new spine was made with synthetic parchment.

 

HUG 4

Book B

 

Book bound in goat parchment, 315 x 205 x 30/ 323 x 220 x 30 mm, titled "B" on the cover by Huygens. Foliated in the upper right corner, including inserts, 125 + 4 ff.; also paginated in lower outer corner; adjunct material, 8 ff. Editors confuse the pagination and the foliation in their citations, violating their own scheme for how they would deal with the two once the book was renumbered in 1928; see OC 16: 435 n.2. Codex is a workbook covering various topics for the period 1661 to 1664. Part of the original bequest.

 

In 2002 the binding was temporarily dismantled by loosening the pastedowns so that folios could be repaired and the book block could be reinforced. This also allowed a tear in the parchment cover to be strengthened with new parchment. In 2006 more repairs were carried out, including the repositioning, folding, and sometimes shaving of former inserts, now bound in, that formerly protruded beyond the cover. In some cases, for the later folios (f. 95 forward), it is difficult to tell whether a folio is original to the book or has been inserted.

 

HUG 5

Book K

 

Book bound in calf parchment, 320 × 210 × 10/ 326 × 220 × 19 mm, titled “K” on the cover by Huygens. Foliated in the upper right corner, 56 ff.; also twice paginated in the upper outer corner (now crossed out) and in lower outer corner. Many folios were removed from the book and many others have pieces cut from them. The only adjunct material is a library check-out sheet and an empty envelope that once held editors’ notes. Codex consists primarily of excerpts concerning astronomy, especially observations of Saturn, taken from his workbooks, including the early <i>parvus libellus</i>, and his readings of other authors for the period 1656 to 1683. If he copied over the date of the original, it has been repeated, even though the passage was obviously recorded here at a later period. Part of the original bequest.

 

Along with the usual repairs during the restoration project of 2003–6, broken parchment laces were repaired with new parchment.

 

HUG 6

Book H

Book bound in calfskin, 315 x 205 x 15/ 324 x 215 x 28 mm, titled "H" on the cover by Huygens. Pages have printed vertical margin lines. Foliated in the upper right corner, 97 ff.; adjunct material, 6 ff. Paginated by Huygens in the upper outer corner through f. 95v (H191), now crossed out in pencil; irregularities in his run are noted but otherwise his pagination is not indicated in the individual records. Codex is a workbook covering various topics for the period 1691 to 1693. Part of the original bequest.

 

During restoration in 2006 the boards of the book, which had separated from the spine, were reattached and the leather joints were repaired with modern leather and dyed Japanese paper.

 

HUG 7

Book G

 

Book bound in goat parchment, 315 x 205 x 25/ 323 x 212 x 32 mm, titled "G" on the cover by Huygens. Foliated in lower right corner, 132 + 1 ff.; adjunct material, 8 ff. Huygens paginated two sections in the upper outer corner, the second comprising ff. 51v-127v, which equals his H1-153 with an added H34.1-2 and f. 91 not numbered. Codex is a workbook covering various topics for the period 1688 to 1691. Part of the original bequest.

 

During restoration in 2006 the spine, which was already separating from the top of the book, was rebuilt. It had shrunk to such an extent that, once the book block had been restored, it no longer fit at all. In order to relieve the tension, its joint with the back cover was slit open, a new joint inserted, and then the binding reattached. Beyond the usual repairs, f. 94, which consisted of two folios pasted together, was unpasted to reveal the hidden text.

 

HUG 7 A

Relative and Absolute Motion (L)

 

Loose sheets of various sizes and dates, called "L" by the editors. Foliated in the upper left corner, 46 + 4 ff.; adjunct material, 22 ff. Codex contains papers pertaining to the question of relative versus absolute motion; see <i>Oeuvres Complètes</i> 21: 415 n.1 for a history of the creation of this codex by the editors. Manuscripts were part of the original bequest.

 

Edited by Gianfranco Mormino in <i>Penetralia Motus</i>. That edition supercedes the <i>Oeuvres Complètes</i> because it reproduces all the manuscripts of the codex, not selective portions.

 

HUG 8

Book I

 

Book bound in goat parchment, 315 x 200 x 25/ 324 x 210 x 40 mm, titled "I" on the cover by Huygens but called "J" by the editors. Foliated in the upper right corner, 135 +11 ff.; adjunct material, 7 ff. Paginated in the upper outer corner by Huygens, sometimes only on recto, to f. 66r [H133], including f. 14bis [H29-30]. Codex is a workbook covering various topics for the period 1693 to 1695. Part of the original bequest.

 

HUG 9

Book E

 

Book bound in goat parchment, 290 x 215 x 30/ 298 x 227 x 40 mm, titled "E" on the cover by Huygens. Foliated in the upper right corner, 130 + 1 ff.; also paginated in lower outer corner; adjunct material, 4 ff. Thirteen folios at the beginning removed. All text written sideways on ff. 41r-48r, excepting f. 42v. Codex is a workbook covering various topics for the period 1674 to 1680. Part of the original bequest.

 

HUG 10

Book A

 

Book bound in goat parchment, 290 x 180 x 25/ 300 x 200 x 33 mm, titled "A" on the cover by Huygens. Foliated in the upper right corner, 132 +1 ff.; also paginated in lower outer corner; adjunct material, 6 ff. Text on ff. 126r-129v upside down and dating indicates that he wrote them from back to front. Blue ink, from a spill by one of the editors, stains the upper inner corner of ff. 78-132, sometimes obscuring the text. Codex is a workbook covering various topics for the period 1658 to 1660 (with some astronomical data added at a later date). Part of the original bequest.

 

The earliest of his workbooks, the volume has undergone extensive reconstruction. So many folios were missing from the front that the spine collapsed and the book became skewed. Even now the book block is not squared on its edges; rather the spine tilts strongly toward the right so that the first folios overhang the last ones by 10 mm. This damage must have occurred very early, resulting in an undocumented attempt to straighten and rebind the book. In the process the edges were trimmed and, since the front folios still overhung, text along the edges of the beginning folios was cut off. This shaving took place before the edition was undertaken, because the editors had to guess the endings of some words. By 2004 the front cover had separated from the book block. During restoration two quires of blank folios were inserted at the front to replace those missing so as to make the book block fit the cover. The bottom of the spine was repaired with new material and the cover was reattached.

 

HUG 11

Geometry

 

Book bound in calfskin, 200 x 155 x 20/ 208 x 166 x 31 mm, not titled by Huygens. Foliated in the upper left corner up to the first (f. 25) of 123 blank folios; 148 ff. total in book; adjunct material, 2 ff. Paginated by Huygens in the upper outer corner; H1—42, —, —, with a repeat of H16 and H17 on two otherwise blank pages. Codex consists of two treatises, the first on Alhazen's problem and the second on constructing conics by means of two equations. The manuscript was written before 2 October 1687, the date given in a note that ends the text. Part of the original bequest.

 

HUG 12

Algebra

 

Book bound in calf parchment, 205 x 155 x 30/ 210 x 165 x 35 mm, titled by Huygens "ALGEBRA" on the cover and "[ÆN]ALYT[IK]" on the spine. Foliated in the upper right corner, 179 + 5 ff.; also paginated in the upper right corner by the editors (now crossed out); adjunct material, 2 ff. Codex consists of two sections of mathematics written by Huygens' teacher, Frans van Schooten Jr, with some work added by Huygens, and a middle portion of remaining blank folios used by Huygens as a workbook for geometric questions. The sections by van Schooten are not edited but only generally described. In particular, the editors conjecture that the second section was written from the back of the book to the front; cf. OC 11: 12. Their claim must be regarded as substantiated only by the logical order of the problems and the reverse order of the dates, because most problems occupy only one page and the few that spill over to another page follow the usual front-to-back order. In addition, the text is not upside down in relation to the rest of the book as is usually the case when someone, particularly Huygens, treats the rear of a notebook as a separate entity. Part of the original bequest.

 

HUG 13

Excerpts from the Workbooks

 

Book bound in sheep parchment, 200 x 155 x 10/ 208 x 170 x 12 mm, titled "Excerpta ex Adversarijs Christiani Hugenij" by Huygens. Ink drawing of a landscape sideways on the cover now nearly obliterated. Foliated in the upper left corner, 32 ff.; also paginated in the upper right corner; adjunct material, 2 ff. Codex consists of copies or restatements of material on a variety of topics which originated elsewhere in the manuscripts, hence corrections to the text and development of ideas are few. Variations in ink suggest that the pieces were not copied as a whole. The editors claim the pieces were entered at the time of the original investigations (OC 16: 312 n.1). Most were written before 5 May 1673, the date given in a marginal note on f. 24v. Part of the original bequest.

 

HUG 14

Sketchbook

 

Book bound in goat parchment, 200 x 155 x 20/ 207 x 166 x 21 mm, not titled by Huygens. Irregularly foliated in the upper right corner, including the skipping of blank pages, 25 + 3 ff. Codex consists of sketches of country scenes drawn in 1658 (foliated on verso), followed by texts that can be dated to around 1670; codex described by the editors in <i>Oeuvres Complètes</i> 20: 291 n.1. Part of the original bequest.

 

HUG 15

Almanac 1686

 

Book bound in calf parchment, 195 x 150 x 5/ 200 x 160 x 9 mm; title on the cover is now illegible. Book is a printed almanac for the year 1686 (<i>Comptoir Almanach Op't Jaar ons Heeren Jesu Christi M. DC. LXXXVI</i>, Amsterdam, G. J. Zaagman) with a folio for each month, followed by 2 blank folios on which Huygens entered notes; middle folios stained green from a ribbon tie. Foliated upper right corner, including the printed almanac pages, 35 + 1 ff.; adjunct material, 1 f. Codex contains notes on <i>La Vie de Monsieur Descartes</i> by Adrien Baillet and observations made with a microscope in 1692. Part of the original bequest.

 

HUG 16

Fortifications Textbook

 

Book bound in calf parchment with green ribbon ties, 155 x 205 x 20/ 160 x 210 x 20 mm, titled "Fortificatij Fr van Schot[enij]" on the spine and "Van Sterckten Bouwen" on the title page (f. 2r). The book consists of 43 folios of notes and exercises on the geometry of star fortresses, followed by 47 blank folios. It is written in an upright hand that does not resemble Huygens' adult style but does look similar to writing on some of his early manuscripts and letters. Three accompanying diagrams on f. 2bis r-v and f. 2ter r(310 x 200) were formerly folded and inserted into the book, now hinged in. Part of the original bequest, as evidenced by the 1716 catalogue.

 

Jan van Maanen has argued that the codex consists of student notes recorded by Huygens at lectures given by Frans van Schooten Jr, at Leiden's school of engineering; cf. van Maanen, <i>Facets of Seventeenth Century Mathematics in the Netherlands</i>, pp. 184-5.

 

HUG 17

Juvenilia

Book bound in calf parchment, 150 x 195 x 20/ 163 x 210 x 25 mm, titled "Juvenilia pleraque" by Huygens; called "boeckje" by the editors because Huygens once referred to it by that name in a letter (cf. OC 11: 4 and OC 14: 412). Foliated in the upper right corner, 82 ff; adjunct material, 2 ff. Huygens paginated those folios with text (and some that are blank) up to p. 34, upper outer corner; a different pagination in lower right corner runs to the end and is cited by the editors in the few cases where they give a page number. The book consists of regular white paper alternating with grey blotter paper; many folios have been torn out, so that the alternation is not consistent; for the most part, Huygens wrote on the white paper. Ff. 74-81 are brittle from having absorbed a liquid (ink, resin, or lacquer of some kind). The numerous missing folios, primarily grey and unlikely to have contained text, are not catalogued below. Variable handwriting, some very upright and not like his adult hand; adult hand begins on f. 66. The codex primarily contains early work in mathematics and mechanics; few corrections, as if transcribed. Part of the original bequest.

 

HUG 17 A

Lensgrinding Machine Design

 

A double folio containing designs for a lens grinding machine. Probably originally folded and interleaved behind HUG 17, f. 59, which contains a related figure. Formerly stored with HUG 17 in an envelope labelled "uit Hug. 17"; now in its own box. Adjunct material, 2 ff. Part of the original bequest.

 

HUG 18

Almanac 1687

 

Paper bound book, 195 x 150 x 5/ 199 x 154 x 6 mm; not titled by Huygens. Book is a printed almanac for 1687 similar to HUG 15. Foliated in the upper right corner, 20 ff.; no adjunct material. Many folios torn out (including the title page), so that the first almanac page is for April; missing folios not catalogued below. Because Huygens wrote on the recto of the almanac folios (ff. 2, 4, 5, 6, 9, 12, 15, 18), they are included in the listings below without being distinguished. Codex relates to two letters written in November 1691. Part of the original bequest.

 

HUG 19

Empty

 

Formerly Huygens' copy of <i>Theoremata de Quadratura, Hyperboles, Ellipsis et Circuli, ex dato Portionum Gravitatis Centro</i>. Leiden: Elsevier, 1651, 8 + 43 pp, 205 x 155 x 5 mm. Annotated by both Huygens and the editors. Reproduced with facing page French translation in <i>Oeuvres Complètes</i> 11: 281-337. Huygens' annotations are added to the main text in brackets or placed in footnotes. No longer housed with the Codices Hugeniani; now in the <i>libri annotati</i> collection (766 F 22).

HUG 20

Empty

 

Formerly Huygens' copy of <i>De Circuli Magnitudine Inventa. Accedunt eiusdem Problematum quorundam illustrium Constructiones</i>. Leiden: Elsevier, 1654; 8 + 71 + 1 pp, 220 x 175 x 8 mm. Annotated by Huygens and the editors. Reproduced with facing page French translation in <i>Oeuvres Complètes</i> 12: 113-215. Two corrections noted by Huygens but not in the errata list are inserted into the main text; cf. OC 12: 145 n.21 and 12: 173 n.50. No longer housed with the Codices Hugeniani; now in the <i>libri annotati</i> collection (766 F 21).

 

HUG 21

Empty

 

Formerly a copy of <i>Christiani Hugenii Const. F. ad C.V. Fran. Xaver. Ainscom, S.I. Epistola, qua diluuntur ea quibus Έξέτασις [Exetasis] Cyclometriae Gregorij à S^to. Vincentio impugnata fuit</i>. ‘s Gravenhage: Vlacq, 1656; 12 pp, 200 x 155 x 2 mm. No annotations or evidence of ownership. Reproduced with facing page French translation in <i>Oeuvres Complètes</i> 12: 263-77. No longer housed with the Codices Hugeniani; now in the rare book collection (536 F 4).

 

HUG 22

Empty

 

Formerly a copy of <i>Horologium</i>. ‘s Gravenhage: Vlacq, 1658; 2 + 15 pp, 205 x 155 x 8 mm. No annotations. Title page has the label "Ex Bibliotheca Viri Illust. Isaaci Vossii" affixed. Vossius did receive a copy from Huygens, cf. OC 2: 209 n.2; no dedication written into the book. Reproduced with facing page French translation in <i>Oeuvres Complètes</i> 17: 41-73. No longer housed with the Codices Hugeniani; now in the rare book collection (539 F 29).

 

HUG 23

Empty

 

Formerly Huygens' copy of the pair of treatises, <i>Eustachii De Divinis Septempedani Brevis Annotatio in Systema Saturnium Christiani Hugenii</i> and <i>Christiani Hugenii Zulichemii Brevis Assertio Systematis Satvrnii</i>. ‘s Gravenhage: Vlacq, 1660; 2 + 23 + 20 + 1, 190 x 145 x 8 mm. Annotated by Huygens. Reproduced with facing page French translation in <i>Oeuvres Complètes</i> 15: 403-67. Annotations consist of corrections to the text, which the editors incorporated without comment. No longer housed with the Codices Hugeniani; now in the rare book collection (1366 D 23).

 

HUG 24

Empty

 

Formerly Huygens' copy of <i>Horologium Oscillatorium sive de Motu Pendulorum ad Horologia aptato demonstrationes geometricae</i>. Paris: Muguet, 1673; 6 + 161 pp, 390 x 220 x 10 mm. "Exemplaire corrigè de ma main". Reproduced with facing page French translation in <i>Oeuvres Complètes</i> 18: 69-368. Minor corrections by Huygens incorporated into the text without comment (see OC 18: 92 n.3); larger ones in notes; figures taken from the 1724 edition. Behind the page of Corrigenda and now bound in is a drawing (110 x 180) of one defective figure; verso has astronomical data in pencil beginning with the date 2 Nov. No longer housed with the Codices Hugeniani; now in the <i>libri annotati</i> collection (755 A 5).

 

HUG 25

Mathematics

 

Loose sheets of various sizes and dates arranged by the editors under the title "Chartae Mathematicae". Foliated in the upper left corner, 219 + 1 ff.; adjunct material, 56 ff. Codex includes a book (sewn folios, no cover) partially used by Philips Huygens to collect words and phrases alphabetically and filled out with mathematical subjects by Christiaan in 1657 after his brother's death. Foliation continues from the main collection (ff. 179-209), but the book is also separately paginated in the upper right corner; editors cite the separate pagination when referring to the "livret de Philips". Codex includes work on a variety of mathematical problems from all periods of his career. Manuscripts were part of the original bequest.

 

HUG 26

Mechanics

 

Loose sheets of various sizes and dates arranged by the editors under the title "Mechanica Varia", also called "Chartae Mechanicae" in <i>Oeuvres Complètes</i>. Title page not foliated, others foliated upper left corner, 211 + 2 ff; adjunct material, 12 ff. Irregular alternative numbering in the upper right corner, particularly in the section devoted to <i>De Iis Quae Liquido Supernatant</i>; current foliation follows Huygens= own pagination, H1-75. Codex includes the draft of <i>De Vi Centrifuga</i>, the draft of <i>De Iis Quae Liquido Supernatant</i>, and manuscripts pertaining to his discovery of the isochronism of the cycloid.

 

The end of the codex (ff. 140-211) consists of Huygens' figures for <i>De Iis Quae Liquido Supernatant</i>, each of the 72 diagrams on its own small sheet. The treatise was never published in the seventeenth century; the figures were used by the editors to prepare the plates for <i>Oeuvres Complètes</i> (see OC 11:90 n.13) but were not reproduced in facsimile. The diagrams were formerly apportioned to 3 envelopes, one for each book of the treatise. During restoration in 2004 they were hinge mounted onto folio sized sheets, 6 per page. Before this treatment, the diagrams tended to wander both within and without the collection, including at one time having their own codex assigned, HUG 26 B. Moreover, twice they were returned to the library from the estates of deceased editors; cf. f. 138 for details. All were part of the original bequest.

 

 

HUG 26 A

Percussion

 

Loose sheets of various sizes and dates arranged by the editors under the title "De motu corporum ex percussione" after the major manuscript contained in it. Foliated in the upper left corner, 196 + 1 ff.; adjunct material, 110 ff. The first draft of <i>De Motu</i> was paginated by Huygens (H1-32); pages H3-6, which pertain to drafts of letters, are now in HUG 45. The last draft of <i>De Motu</i> was transcribed by his assistant Denis Papin from folios in the codex that are no longer in the copied order but bear instructions by Huygens concerning the sequencing, thus allowing for a reconstruction of the autograph. The copy was edited in <i>Opuscula Postuma</i>, from whence came the version in <i>Oeuvres Complètes</i>. Part of the autograph for the last draft is still together (ff. 58-62) and comprises the portion of <i>De Motu</i> communicated by Huygens to the Royal Society in 1666. Manuscripts were part of the original bequest.

 

HUG 27

Music

 

Loose sheets of various sizes and dates arranged by the editors under the title "Musica". Foliated in the upper right corner, 69 ff; adjunct material, 2 ff. Huygens paginated two large runs, ff. 26r-45v, 65r-67v [H1-46] and ff. 56r-61r [H1-11]. Codex includes his work on the division of the octave into 31 tones. Manuscripts were part of the original bequest.

 

In <i>Christiaan Huygens: Le cycle harmonique</i>, Rudolf Rasch gives a concordance of the codex with <i>Oeuvres Complètes</i>, discusses many of the folios, and reproduces some images not edited to <i>Oeuvres Complètes</i>.

 

HUG 28

Astronomy

 

Loose sheets of various sizes and dates arranged by the editors under the title "Chartae Astronomicae". Foliated in the upper left corner, 263+8 ff; adjunct material, 92 ff. Codex includes drafts of <i>Kort Onderwijs, Descriptio automati planetarii, Memorien aengaende het Slijpen</i> (cited with separate pagination by the editors), <i>De Saturni luna observatio nova</i>, and the beginning of a French version of <i>Cosmotheoros</i> (not presented as a whole by the editors). Manuscripts were part of the original bequest.

 

HUG 29

Dioptrics

 

Loose sheets of various sizes and dates arranged by the editors under the title "Dioptrica". Foliated in the upper left corner, 294 + 5 ff.; adjunct material, 78 ff. Codex is a complex set of drafts for a treatise on Dioptrics, collected together but never published by Huygens. He paginated the drafts twice, in ink for an early compilation and in red chalk for a later collection that encompassed the first; the two numberings are indicated by H and R in the physical description of the folios. Some additions and corrections are also in the red chalk, probably an indication that they are contemporary to his second numbering. Also in the codex, ff. 209r 252v, is a copy transcribed by Antoine de Niquet of the early draft (H sequence).

 

The later compilation (R sequence) was followed by the editors of <i>Opuscula Postuma</i> for their edition of <i>Dioptrica</i>. The editors of <i>Oeuvres Complètes</i> 13, wanting to present the work in semichronological order, followed the H sequence but added passages written after Niquet copied it as well as some passages Huygens had crossed out, including alternative phrasing. The added passages are italicized in this hybrid edition. In addition many sections of text are edited to the footnotes. Although the editors undoubtedly relied on Niquet's clean transcription for the main, non-italicized text, the edition seems to follow the original in Huygens' hand, with minor variants with Niquet's copy indicated in the footnotes. However, certain pages of the H sequence are missing, and the Niquet copy is definitely the source for those sections. The Niquet copy is paginated (N1-84) but many of the numbers deteriorated before the folios were stabilized during restoration. The editors made many smaller changes that are not acknowledged, such as incorporating marginal notes into the main text, reordering sections of the text, adding lettering to diagrams, and compressing derivations. The editors provided facing page French translations for most. Manuscripts were part of the original bequest.

 

HUG 29 A

Cartesiana

 

Loose sheets of various sizes and dates arranged by the editors under the title "Cartesiana". Foliated in the upper left corner, 81 ff.; adjunct material, 29 ff. Codex contains material concerning Descartes which was previously stored in other Codices Hugeniani (internal notes refer to HUG 27 and HUG 29). Also in the codex are printer's proofs of pages that did not appear in the published <i>Oeuvres Complètes</i> because the material was not directly by or for Huygens. Manuscripts were part of the original bequest.

 

HUG 30

Childhood Records

 

Two books, each in its own box, containing notes in Dutch on the Huygens children, particularly their educational progress. Provenance is very unclear (see the introduction for details). Presumably they were owned by Constantijn Huygens Lz, because he excerpted parts of both volumes (HUG 32, ff. 4r-5r). They were subsequently separated, then reunited (see letter in front of HUG 30: 1). J. A. Worp handled them in 1911 and claimed he had them on loan from Justine de Glinka. Apparently they entered Leiden University Library in 1915 but were never recorded properly, so that their existence in the collection went unnoticed.

 

The two books have been edited by A. R. E. de Heer and A. Eyffinger in <i>Huygens Herdacht</i>, pp. 75-165. Approximately 80% of the material in HUG 30: 2 and some paragraphs of HUG 30: 1 were previously edited by J. A. Worp in "De jeugd van Christiaan Huygens, volgens een handschrift van zijn vader".

 

HUG 30: 1

 

Book bound in calf parchment with leather ties, 310 x 205 x 15/ 317 x 210 x 25 mm, titled on its cover "Famile Aanteekeningen waarin de geboorte &^ca der kinderen van Christiaen Huijgens den Oude alsmede derchen aanteekingen met notatie ter zyne kinderen vervolgte daer Constatijn Huijgens van Zuilechems Secretaris &c d. s. prinsen Van Orange tot 1633". Foliated in the upper right corner, 32 + 1 ff.; blank folios, including those that come between text pages, not numbered. Pasted onto the front flyleaf is a letter relevant to the history of the volumes. Adjunct material, consisting of an editorial note, inserted in it.

 

HUG 30: 2

 

Book bound in calf parchment with green ribbon ties, 310 x 200 x 20/ 320 x 212 x 30 mm; titled on its cover "Familia aenteekeningen van Constantijn Huijgens raadkende desyne kinderen van Anno 1638". Foliated in the upper right corner, 17 + 4 ff.; three folios cut from behind the flyleaf; blank folios not numbered; no adjunct material.

 

HUG 31

Physics

 

Loose sheets of various sizes and dates arranged by the editors under the title "Physica Varia"; called by that title by the editors except in <i>Oeuvres Complètes</i> 17, where its manuscripts are erroneously attributed to "Chartae Astronomicae" (HUG 28). Foliated in the upper left corner, 312 + 8 ff.; adjunct material, 31 ff. It was the most severely damaged codex in the collection, with many folios flaking away at the edges and, hence, loss of text before being stabilized during restoration. The first section contains Huygens' work on parhelia and magnets, including a set of double folios (ff. 162-178) that appears to be a draft for a treatise on magnetism that would unite two previous studies (not edited as a whole). The second (ff. 188-252) and third (ff. 254-312) sections consist of two drafts of <i>Traité de la lumière</i>, neither of which is the printer's draft. Both are through-written copies made on uniformly sized pages by amanuenses with corrections added by Huygens, including the insertion of added pages. Copy 1 was made while Huygens still lived in Paris; remnants of thread indicate that the double folios were formerly sewn together. Copy 2 is a recopy of the first with Huygens' corrections to the first included and was done shortly before publication (1690); edges severely deteriorated with loss of text, particularly his pagination. See the editors' description, <i>Oeuvres Complètes</i> 19: 382-6, which includes samples of differences between Copy 2 and the finished treatise; the editors reproduce the text of the published treatise. Manuscripts were part of the original bequest.

 

HUG 32

Royer Collection

 

Loose sheets of various sizes and dates, all pertaining to the Huygens family; called "Portefeuille Varia [1]" by the editors. Foliated in the upper left corner, blank folios not numbered, 192 + 6 ff.; adjunct material, 25 ff. The only items in Christiaan Huygens’ hand are ff. 168-192. Most of the material was written or conserved by Christiaan's primary heir, Constantijn Huygens Lz, and later gathered together by A. J. Royer, who willed them to the library in 1809. Adjunct material includes editorial notes regarding Christiaan=s annotations to the <i>Acta Eruditorum</i>.

 

Many of the items concern the work that Christiaan and Constantijn Jr did grinding lenses, including catalogues of lenses for possible sale. A large set of lenses themselves came with the Royer donation; these are now housed in the Museum Boerhaave with others by the brothers. In tracing the history of <i>The Huygens Collection</i> at the museum, Anne C. van Helden and Rob H. van Gent discuss some of the items in HUG 32 and quote Royer’s will.

 

The first item in the codex is a list of what Royer donated. A comparison with the current state of HUG 32 shows that many pieces on the list have been removed from the codex, while others may have been added. Letters appear to have been moved into HUG 45. Christiaan’s diary of his trip to Paris and London in 1660-61 has definitely been moved to HUG 40, ff. 5-22. It is unclear what the phrase "Problema Mathematicum, manu Hugenii Scriptum" at the end of the list refers to, because no mathematics in Christiaan’s hand is now in the codex. Perhaps the phrase refers to the set of papers made by Huygens using his new printing method, the first of which is "Problema Alhaseni". Otherwise, ff. 18, 128-9, 144-51, 163-190 are not specified on the list. If an OC citation is not given, the manuscript was not edited in <i>Oeuvres Complètes</i>.

 

HUG 32 A

Dubrunfaut Collection

 

Loose sheets of various sizes and dates, all pertaining to the Huygens family; called "Portefeuille Varia [2]" by the editors. Foliated in the upper left corner, 212 ff.; adjunct material, 106 ff. The only items in Huygens' hand are ff. 2-16, which are title pages for his manuscripts that have migrated to this set from the original bequest. See the introduction and Yoder, "Archives", for a discussion of the title pages. Except for excerpts from these, none of the material was edited in <i>Oeuvres Complètes</i>.

 

Most of the material was bought from the "Collectie Dubrunfaut" sold by the Parisian auction house Charavay in 1884; f. 19 (in adjunct material) lists the items purchased. The list seems to include ff. 28-121 (excluding adjunct material), although there are some discrepancies with respect to date or sender. About a third of those items were listed in the 1825 Sypesteyn catalogue and were purchased at that time by the London dealer Thorpe. Presumably A. P. Dubrunfaut acquired them from Thorpe or some intermediate owner. Some items inventoried by f. 19 are no longer in the codex but are elsewhere in the collection; viz. HUG 41, HUG 42: 1, HUG 43, f. 10, and HUG 44, ff. 116-156. In contrast, extraneous papers, including editors' notes and transcriptions, have been added (most now in adjunct material).

 

The set includes letters written to Constantijn Huygens from his family while he was in London for the first time and annotated by him with the dates that he received them. Letters by his mother were misattributed as being by his sister and brother because of her use of the endearment "Lief breur". Stating in his notes that he did not know where the manuscripts were, J. A. Worp edited 10 of these letters in <i>De Briefwisseling van Constantijn Huygens</i> from copies made by J. H. W. Unger, who probably encountered them when he edited Constantijn’s diary of 1624 and other items formerly in the set.

 

HUG 33

Empty

 

In the standlijst and 1932 catalogue this codex was described as containing letters that passed between Christiaan and other members of the Huygens family and were part of the royal donation of 1823. It is presumed that all letters are now contained in HUG 45.

 

HUG 34

Family Correspondence

 

Letters to members of the Huygens family, from a variety of correspondents but primarily from Sébastien Chièze, member of the parliament in Orange and agent of the House of Orange in Madrid, and François van Aerssen van Sommelsdijk, Heer de la Platte, a close friend of Constantijn Huygens Jr. Also included are letters passing between members of the family, especially ones involving Philips Doublet and Lodewijk Huygens. Repackaged during the 2003–6 restoration project, the letters are arranged alphabetically by sender then recipient, with each correspondence set in its own folder(s); 456 letters total. Adjunct material, consisting primarily of old covers, is stored in a separate box. Letters were part

of the royal donation of 1823.

 

None edited in <i>Oeuvres Complètes</i>. Letters to Constantijn Huygens were edited by J.A.Worp in <i>De Briefwisseling van Constantijn Huygens</i>. Worp also cites the van Aerssen set in <i>BCH</i> 5: 314 n.6.

 

The metadata for HUG 34 is a modification of the listings for this codex in the national database of letters, Catalogus Epistularum Neerlandicarum (CEN). The letters in this codex have not been individually inspected for this online collection.

 

HUG 34 A

Cosmotheoros

 

Autograph of the posthumously published <i>Cosmotheoros</i>. Foliated in upper right corner, 37 + 4 ff. Originally a collection of loose sheets of various sizes, mostly 310 x 205 mm, paginated by Huygens in upper outer corner. At some stage the collection was bound; restored and rebound in 1980. During the 1980 restoration corrections that had been pasted over passages were loosened, then bound into the codex so as to cover their original positions; they are now indicated by the folio to which each was attached followed by a lower case letter, e.g. f. 8ra. Four pages were covered with full-page corrections; those now are separated and assigned bis numbers. Part of the royal donation of 1823.

 

In the margins someone has written the subheadings and corresponding page numbers of the 1698 edition. With the exception of a few punctuation changes, the printed text of 1698 is a faithful transcription of the Latin manuscript as corrected by Huygens. The marginal subheadings were added and figures were reproduced from drawings found elsewhere in the Huygens collection. Reprinted in <i>Oeuvres  Complètes</i> 21: 677-821 with facing page French translation.

 

HUG 34 B

Correspondence of Constantijn Huygens Jr

 

Letters from Constantijn Huygens Jr to Lodewijk Huygens; arranged chronologically, with 5 undated and a gap from 1654 to 1660; 103 letters total. The first six are in Latin; 17 May 1645 to 8 July 1645. The remaining 97 are in French; 4 Oct 1649 to 7 Aug 1684. Those dated 1645 to 1654 and two undated ones were damaged by water severely enough so that some passages were washed out. Some damaged letters were pasted onto heavy double folios, presumably for reinforcement, which only caused further deterioration; removed during restoration. As is usual with the family letters, the address is often casual ("a Louis mon frere") and the signature, when it appears at all, is C. Huygens, thus not avoiding ambiguity. Letters were part of the royal donation of 1823.

 

None of the letters are edited in <i>Oeuvres  Complètes</i>. Probably the letters from Constantijn Jr to Lodewijk that were edited were moved from here to HUG 45 by the editors.

HUG 35

Empty

 

In the standlijst and the 1932 catalogue this codex was described as holding the drafts of letters written by Christiaan Huygens that were part of the royal donation of 1823. It is presumed that all letters are now contained in HUG 45.

 

HUG 36

Copybooks

 

Two books bound in parchment (or bleached leather) with green ribbon ties, each 330 x 205 x 55/ 335 x 215 x 60 mm, containing copies made by Constantijn Huygens Lz, of letters to and from his uncle, Christiaan; called "Apographa" by the editors from a label pasted on their covers. Foliated in the upper right corner, 249 and 241 ff; HUG 36: 1 also paginated in lower outer corner on even pages. The copybooks, as well as the drafts and family letters upon which they are based, were part of the royal donation of 1823.

 

HUG 36: 1

 

The first volume contains copies of letters between the Huygens brothers, arranged by sender and recipient, with each section then chronologically ordered behind its own title-page. Pasted into the front (ff. 2-3) is Christiaan's diary from his trip to England in 1689. The copies, made from originals then in Constantijn Lz's possession, vary in completeness, primarily because he skipped or summarized non-scientific passages and sometimes melded multiple letters to the same brother (under the date of the last in the sequence) if the topic continued on in the next letter or two. In <i>Oeuvres Complètes</i> 22: 176, the editors cite an extreme case as example of his poor transcribing abilities. Nonetheless, the originals upon which the transcriptions are based are readily identifiable, and someone has even entered the corresponding letter numbers as given in <i>Oeuvres Complètes</i> into the margins. In addition to that numbering, each transcription is numbered sequentially through the book, 1-413. Of the 430 letters copied in whole or in part, 410 are now owned by UBL (3 not in HUG 45) and 17 are owned by other libraries. The copies are entered in the inventory of letters.

 

HUG 36: 2

 

The second volume, titled <i>Christiani Hugenii Zulichemii Viri Nobilissimi et Eruditissimi Zelhemi Toparchae, et Regiae Academiae quae Parisiis est, Membri Epistolae Ad permultos sui Saeculi Viros in quibuscumque studiis, Mathematicis Geometricis et Opticis praesertim celeberrimos</i>, contains copies of the drafts of letters to people outside the family. The copies, made from drafts and summaries then in Constantijn Lz's possession, are reasonably accurate and complete, with the exception that he would sometimes suppress the names of persons mentioned. The transcriptions are not numbered sequentially and have few letter numbers as given in <i>Oeuvres Complètes</i> in the margins. In his uncompleted catalogue C.B. Burch provided those numbers for almost all, and I have made use of his work. With the exception of one section of letters from 1686-87, which appears in the middle of those for the 1660s, the transcriptions are semi-chronological. Departures from strict chronology seem to reflect Christiaan's habit of writing more than one draft on the same sheet. It seems reasonable to presume that Constantijn Lz merely copied the pages in the order that he found them; that is, although they are now stored as much as possible alphabetically by recipient, they were probably originally kept chronologically. Of the 325 letters copied (including 6 originals), 319 are now owned by UBL and 3 are owned by other libraries. The copies are entered in the inventory of letters. A few non-letter items seem to have been interspersed with the drafts and thus copied. As readily noted from their listings below, in most cases they are no longer stored with the drafts.

 

HUG 37

Correspondence of Constantijn Huygens

 

Letters and some poems, primarily addressed to Constantijn Huygens; 2467 letters total. Repackaged during the 2003-6 restoration project, the letters are arranged alphabetically by sender then recipient, with each correspondence set in its own folder(s). Adjunct material, consisting primarily of old covers, is stored in separate boxes.

 

The codex is presumed to have been part of the royal donation of 1823, although T. Jorissen in "De Handschriften van Huygens", which is his accounting of the partitioning of the donation, does not record any transfer of Constantijn's letters to Leiden University Library. In the Geel catalogue of 1852, which assumes they are part of the royal donation, the letters are described as being arranged in two codices by volumes (three volumes for the first codex, five for the second) spanning various years (sometimes overlapping) and only then alphabetical within the volumes. An extensive sampling of Geel's list reveals that the two sets are intact in HUG 37 and that they were all edited by J.A. Worp in <i>De Briefwisseling van Constantijn Huygens</i>. True to contemporary editorial style, Worp only cited letters by their holding libraries and sometimes provided a synopsis in Dutch rather than a full transcription.

 

The following is a modified version of the listings for this codex in the national database of letters, Catalogus Epistularum Neerlandicarum (CEN), as provided by the staff of Leiden University Library. These listings parallel the order of the folders in which the letters are stored. The records of secondary letters that do not have their own folders but are stored with those of another correspondent are italicized. Note that for institutions the location precedes the title of the organization; e.g. for "Regering van Zutphen" see "Zutphen". The letters in this codex have not been individually inspected for this catalogue. Those edited in <i>Oeuvres Complètes</i> are detailed in the inventory of letters.

 

HUG 38

Empty

 

In the standlijst and 1932 catalogue this codex was described as having letters and poems written to Constantijn Huygens. It is presumed that all letters are now contained in HUG 37.

 

HUG 39

Correspondence of Laurens Back

 

Letters from Laurens Back (Bacx) to his nephew, Christiaan Huygens Sr; arranged chronologically, 28 Jan 1589 to 6 Feb 1614; in Dutch; 11 letters total. Numbered by item, not by folio; 13 items. Codex also includes a biography of Back (no. 13) and a notarized copy of an agreement between Back and Elizabeth Ghibault, 24 Sept 1605 (no. 8). Adjunct material consists of an old library cover detailing the provenance; loose in the box. Purchased at auction from the estate of J.W. Sypesteyn, the Hague, April 1869, lot #226, by F.C.L. Wynmalen, who donated them to the library.

 

The letter of 6 Feb 1614, sent from Bantam, was edited, no author given, in "Brief van Laurens Back aan Christiaan Huygens”. Letter of 4 Mar 1613 also quoted in the article.

 

HUG 40

Travel Diaries of Christiaan Huygens

 

Loose sheets, foliated in the upper left corner, 26 ff; also paginated in the upper right corner (crossed out). Adjunct material includes outlines by the editors of Huygens’ work in various fields of science; 4 ff. With the exception of the last two sheets, codex consists of a daily diary of his trip to France and England in 1660-61. The last sheets are a series of undated comments covering his visit to England in 1663. Part of the Royer bequest of 1809; cf. HUG 32.

 

HUG 41

Travel Diary of Constantijn Huygens

 

Loose sheets, 310 x 200 mm, foliated in the upper right corner, 4 ff.; adjunct material, 1 f. Codex consists of Constantijn Sr’s journal for his aborted voyage to England, 26 February to 5 March, 1624; in Dutch. Signed "Constanter". Part of the Dubrunfaut collection purchased in 1884; cf. the inventory of HUG 32 A, f. 19.

 

Edited by J.H.W. Unger in "Dagverhaal eener Reis naar Engeland door Constantyn Huygens".

 

HUG 42

Family Biographical Records

 

HUG 42: 1

 

Loose sheets, foliated in the upper right corner, 2 ff.; adjunct material, 1 f. Codex consists of Christiaan Huygens Sr’s notes regarding the upbringing of his children; written on pages cut from the end of <i>Les Paraphrases d’Erasme divisées en deux Tomes</i>, Basle, 1563. Similar to the material in HUG 30: 1. Part of the Dubrunfaut collection purchased in 1884; cf. the inventory of HUG 32 A, f. 19.

 

Edited by J.H.W. Unger as appendix A to "Dagboek van Constantijn Huygens".

 

HUG 42: 2

 

Loose sheets of various sizes, foliated in the upper right corner, 15 ff.; no adjunct material. Codex includes a variety of materials, such as drawings of coats of arms, that have to do with Constantijn Huygens. Provenance is unclear. The standlijst for HUG 42 only includes the item now occupying HUG 42: 1, followed by the erroneous annotation that it was purchased from the auction house Charavay, Paris, in 1886. Perhaps the other items now in HUG 42: 2 were purchased from Charavay in a separate sale in 1886, for which there is some limited documentation in Leiden University Library records. However, the lack of a complete inventory of those items at that point in the standlijst suggests that they were not yet in the collection and the date was a slip of the pen for the single item listed. (The entry is followed by an itemized list in the same hand for HUG 44, which is from 1886.)

 

HUG 43

Foreign Titles given Constantijn Huygens

 

Loose sheets of various sizes, foliated in the upper right corner, 10 ff.; no adjunct material. Most of the pieces pertain to titles Constantijn Huygens received in England and in France, including many drawings of potential coats of arms reflecting his new status. Some items, if not all, were previously in the possession of J.T. Royer, who annotated two (ff. 6 and 10). The subsequent history of the codex is unclear. The standlijst for HUG 43 only includes one item, f. 10, followed by the annotation that it was purchased from the auction house Charavay, Paris, in 1886. However, that particular item was part of the Dubrunfaut collection purchased in 1884; cf. the inventory of HUG 32 A, f. 19. Adding to the confusion, the second item annotated by J. T. Royer, f. 6, is not listed in that inventory, and presumably entered the collection along with the other items by a separate route, perhaps along with the equally undocumented HUG 42: 2.

 

HUG 44

Wills

 

Loose sheets of various sizes; numbered by the folder as well as foliated in the upper left corner, 156 ff in 14 folders; adjunct material, 13 ff. Codex consists of copies of wills of members of the Huygens family, including Christiaan, with some estate inventories included. All but one were purchased at auction, 12 April 1886, from the auction house W.P. van Stockum, ‘s Gravenhage, acting as agent for the printer H.H. Belinfante, A.D. Schinkel’s successor. Schinkel himself purchased them at auction, 29 Nov 1837, from W.P. van Stockum, acting as agent for the estate of Jacob Schonk, who probably inherited them from one of his aunts, who numbered among the heirs of Susanna Louise Huygens. The remaining item, namely the inventory of Constantijn's estate, was part of the Dubrunfaut collection purchased in 1884; cf. the inventory of HUG 32 A, f. 19.

 

HUG 45

Correspondence of Christiaan Huygens

 

Letters or drafts of letters to and from Christiaan Huygens; 2234 letters [2294 as edited] total. Repackaged during the 2003-6 restoration project, the letters are arranged alphabetically by sender then recipient, with each correspondence set in its own folder(s). There is no segregation of folders by whether the letters are originals, drafts, or copies. Usually the editors pencilled onto the letter the number that they assigned to it. Adjunct material, consisting primarily of old covers, is stored in separate boxes.

 

When this cataloguing project began, the letters had been arranged, most likely by the editors, into three major divisions: alphabetically by sender when Huygens or another person was the recipient, thus including third-party letters; alphabetically by recipient when he was the sender, therefore primarily drafts but also including originals that entered the collection from acquisitions; all family letters, excepting those with Philips Doublet, who remained in the first two sections. The family letters were further subdivided. Most of the letters in the first section were part of the original bequest. The drafts were part of the royal donation and were originally housed in a separate codex, HUG 35. Most of the family letters were also acquired as part of the royal donation, and were originally in HUG 33. Given that the tripartite arrangement led to confusion, the entire set was reorganized into the current arrangement. Because all letters involving Christiaan were merged into HUG 45, the provenance of individual letters cannot usually be determined.

 

The letters are described individually in the inventory of letters. The following is a modified version of the listings for this codex in the national database of letters, Catalogus Epistularum Neerlandicarum (CEN), as provided by the staff of Leiden University Library. The list includes the number of letters in each folder; in cases where the editors separated a letter into two entries, thereby changing the count, I have added the number "as edited" in brackets. For this codex, full names are given in the index of names accompanying the letters inventory. These listings parallel the order of the folders in which the letters are stored. The records of secondary letters that do not have their own folders but are stored with those of another correspondent are italicized. Note that for institutions, including journals, the location precedes the title of the organization; e.g. for "Regering van Zutphen" see "Zutphen". To maintain consistency with the CEN, I have not translated these entries here.

 

HUG 45 Kaarten

Maps

 

Two large maps that have been segregated from the documents to which they were originally attached in order to store them unfolded. During the restoration project a large genealogy chart from HUG 46 was added to the box so that it could likewise be stored unfolded; the folder of other materials housed with the chart as HUG 46 #7 (ff. 40-45) was also brought over; adjunct material not segregated.

 

HUG 46

Genealogical Records

 

Loose sheets of various sizes, numbered by the folder as well as foliated in the upper right corner, 77 ff. in 11 folders; adjunct material in a separate folder, 23 ff. The codex contains copies of wills of members of the Huygens family, including Constantijn and Christiaan (second copy), marriage contracts, family registers of titles and positions held, and genealogy charts that are in some cases mutually inconsistent. Items were purchased at auction, January 1899, from J.L. Beyers, Utrecht, agent for the estate of Rooyaards van den Ham, lot #3235.

 

HUG 47

Family Records

 

Loose sheets of various sizes. Each codex foliated separately in the upper right corner, 16 and 4 ff.; no adjunct material; stored in the same box.

 

HUG 47: 1

 

Codex consists of genealogical records, purchased at auction January 1899 from J.L. Beyers, Utrecht, agent for the estate of Rooyaards van den Ham, lot #3234.

 

HUG 47: 2

 

Codex consists of a list of the manuscripts of Constantijn Huygens, 4 ff.; f. 4 blank. Purchased from W.P. Stockum in 1886; cf. HUG 44. The list was edited by A.D. Schinkel in <i>Opgave der Handschriften van Constantijn en Christiaan Huygens</i>. Schinkel, who previously owned it, claims that the list was made by Jacob Schonk from whose estate he purchased it. With one transposition, the list is the same as that edited by T. Jorissen in "De Handschriften van Huygens". Both are essentially catalogues of the royal donation of 1823. Jorissen identifies the receiving libraries.

 

HUG 48:1 / HUG 48:2 / HUG 48:3

Papers of Constantijn Huygens

 

Loose sheets of various sizes. The first two codices are foliated separately in the upper right corner, 15 and 61 ff.; adjunct material, 7 and 28 ff.; stored in separate boxes. All items but one were purchased at auction, April 1906, from F. Muller & Co, Amsterdam, as agent for the estate of van Havre, lot #163; cf. the auction list, HUG 48: 1, f. 1 (in adjunct material folder). The other item, namely the will of Susanna Huygens-Hoefnagel, is not included in the auction list but is included with the other items in the Standlijst for HUG 48 (at that point not subdivided). It might have been designated HUG 48: 3 for that reason, but that codex is now empty.

 

HUG 48: 2 consists primarily of letters to Constantijn Huygens in his capacity as secretary to the Prince of Orange, but also includes two to Christiaan Sr and three to Christiaan.

 

HUG 48: 3 is empty.

 

HUG 49

Latin Grammar

 

Notebook with marble paper cover, 190 x 160 mm, in which Constantijn Huygens Sr summarized the rudiments of Latin grammar. Foliated in the upper right corner, 10 ff.; f. 10 blank, f. 9v ends with the date Idus April 1640. Adjunct material loose in the box, 1 f. Purchased from bookdealer B.N. Israel, April 1949.

 

In HUG 30: 2, Constantijn Huygens says that he wrote this <i>rudimenta partium orationis</i> for his sons in early 1650 by asking questions about basic Latin grammar in Dutch and answering them in Dutch. Each pairing is then followed by examples in Latin. He had the booklet copied so that Constantijn Jr could take one with him to Utrecht; this might be that version since it is not in the father’s hand.

 

HUG 50:1 / HUG 50:2 / HUG 50:3

Miscellaneous Manuscripts

 

Loose sheets of various sizes and dates, arranged by the editors under the title "Portfeuille anonyme". Each codex foliated separately, HUG 50: 1 in upper left corner and HUG 50: 2 and 3 in upper right corner, 6, 105, 1 ff.; adjunct material 5, 1, 1 ff.; stored in the same box. The group was removed from Leiden during the editing process, deposited in a safe at Haarlem, and remained unnoticed for over 50 years; cf. OC 21: 824 n.1. Hence, none of the material was available during the preparations of volumes 1-20. Many pieces are related to material in other codices, and many are not by Huygens. It is not clear why they were separated out, although some might have originally been inserts in the workbooks. Not all were part of the original bequest, however, because Constantijn Huygens Lz copied some pieces, which indicates those items were originally stored with the drafts or other papers available to him.

 

HUG 51

Editors' Notes

 

A collection of notebooks and packets of notes made by the editors of <i>Oeuvres Complètes</i> during the course of their work; numbered by the piece, 33 items. There are many lists of citations to pages in <i>Oeuvres Complètes</i>; however, they frequently refer to preliminary printings and not to the published work, so researchers who consult them should not expect agreement between those lists and the present catalogue.

 

HUG 52

Correspondence of Noel de Caron

 

Book bound in leather, 350 x 235 x 10/ 365 x 250 x 25 mm, with the title "Manuscript letters of Sir N. de Caron, 1588-1619" imprinted on the spine and the book plate of Henry B.H. Beaufoy on the inside front cover. Book consists of blank folios, gilt-edged, onto which have been pasted seven letters in French from Sir Noel de Caron to Christiaan Huygens Sr, all signed and all but the fourth addressed; 12 Mar 1588 to 21 Dec 1619. Each is followed by its transcription and an accompanying translation into English. Each set of the seven has been numbered in the upper right corner. Opposite the first letter is a hand-drawn map (after a printed survey of 1814) of South Lambeth.

 

Loose in front is a summary in English (3 ff.) of the book's contents by A.G.H. Bachrach, including the remark that the letters are at the dealer Sotheran, Sackville Street, London. Pasted into the book on the first page is a letter, 11 May 1950, from Bachrach giving thanks for being allowed to see the collection and noting that the letters are to Christiaan Sr and not to Constantijn. On the same page are two excerpts from sales catalogues, both with annotations identifying the dealer as Sotheran but with different prices. The catalogue descriptions include the transcriptions and translations as well as the letters. The descriptions also note that de Caron built Caron House, South Lambeth, and Beaufoy’s estate subsequently encompassed it. The catalogue for the Sypesteyn auction of 1825, lot #392, lists six letters, 1588 to 1619, from de Caron to "Secretary Huygens", which were bought by Harden. Their subsequent ownership is unknown. Presuming that these are the same set, they obviously came into Beaufoy’s possession other than through the acquisition of Caron House. Purchased from Sotheran by UBL, 25 Sept 1950.

 

The Codices Hugeniani Online (COHU) contains the fully digitized archive of Christiaan Huygens which is held at Leiden University Library. The archive is divided in some fifty plus codices (see the tab “ “Codex Description” for details of each of them), and these codices are used as the main entrance points for COHU.

 

Under the tab “Content” you will find the full list of codices ordered from 1 to 52. By clicking on a codex you will receive the list of individual records in that codex. The records are ordered by folio number. One record can describe one or more folios. The subdivision that Joella Yoder has made in her Catalogue of the Manuscripts of Christiaan Huygens is the basis for this.

 

Clicking on a record title, will take you to the document landing page. Here you’ll find the reader to view the digitized papers, and you will see all the available metadata for this record.

 

Description of the metadata fields

 

HUG – This indicates the number of the codex.  

Title – The title of one or several pages consists of the HUG number followed by the Folio number(s).     

Folio number - Folio numbers were assigned by the library to the adjunct material that was formerly interleaved with the manuscripts, hence they appears in the listings, although the actual material has been replaced by blue archival paper, as noted in the history of the restoration project. In order to leave no gaps in the accounting, blank folios that are numbered but hold no text or other matter are merged to the end of a folio span. Folios that were accidentally unnumbered are assigned a bis number.

Because the editors reproduced the manuscripts according to subject matter, a single folio might have been apportioned to more than one volume and also still contain unedited material. To account for this partitioning of the text by the editors, each portion of a manuscript that appears in non-contiguous sections of the edition is given its own record. Multiple partitions are listed in order of their appearance on the folio. On the other hand, partitions made by the editors (such as division into paragraphs) that are reproduced contiguously are subsumed in one record, except in the cases where the partitions have been treated as self-contained works (as indicated by the table of contents).

Ideally, the folio spans should make a continuous run, once the individual partitions are included. However, for a short item that the editors pulled out from a long span and edited elsewhere, the record is listed behind the span rather than divide the span into two records. Thus, for example, in HUG 1,

the record for f. 3r follows that for ff. 2r–4v. Footnotes that quote additional text from the same folio span as the main text, or are repeated as main text elsewhere in the edition, are not given a separate record; those from a different place in the collection are given their own records, which then appear in the concordance.        

Size – Size is height by width expressed in millimeters but only measured to half-centimeter accuracy. If the size for the next entry is the same, such as when the verso is catalogued separately, it is not repeated. If the folio span includes more than one size, the second value will be noted in the physical description behind the folio with that size. The size of the uniform folios in a workbook is given by the book block size in the general description of that codex; only the sizes of inserts to the book are given in its inventory.    

Concordance with OC - When the material is not described by the editors of the OC, this fields says ‘not edited’. If the piece has been edited by someone else, the particulars of its publication are briefly described.

Incipit - Incipit (Latin for “it begins”) should be the beginning phrase of the manuscript, or portion of manuscript. However, to facilitate _nding the corresponding section in the Oeuvres Complètes, the leading words of the edited section are quoted in cases where the editors placed another phrase first, which they often did if the manuscript began with a mathematical derivation. If there is a transcription error in their “incipit”, however, it is corrected without comment. Family manuscripts and other secondary material are described, but not detailed by their incipits or sizes.

Dates - Dates are presumed to be new style unless indicated otherwise by the author. No conjectured dates are included. This approach is in contrast to the inventory of letters where conjectures are more certain because of the back and forth nature of correspondence. If Huygens dated the page at the top and started writing with a new line, the date is not repeated in the incipit so that more text can appear. If Huygens included the date in the text of the first line, the date appears in the incipit. If it is clear that the date in the incipit is only part of the text and not the actual day of composition (such as his notes on astronomical records), the date is not listed separately.

Physical Condition - Physical condition, such as additional folio sizes and blank or empty folios, is

described first. If Huygens himself paginated the folios, that number appears as H___.    

Not edited - If the majority of a manuscript has been edited and has an OC citation, but substantial related material also appears on the page, that supplementary unedited material is described. If that unedited material is extensive, its scope is estimated by the number of pages it would occupy if it were continuous text. For the most part, following the practice of the editors, the passages that were crossed out are not described. Users should be aware that the manuscripts abound in cross outs and minor passages that are not detailed here.              

Content - Content is not described if the piece has been edited, because the user can make an independent judgment of content from the published text. The description of unedited material is brief.

Linking OC  - A hyperlink to the OC on the DBNL is provided. The link directs you to a chapter in the OC, were you might have to scroll down to the page you are looking for.

 

 

Metadata fields specifically for the letters

 

Title - The title of a letter consists of the HUG number followed by the Letter number.

Letter number - Letter numbers were assigned by the editors of the OC according to chronological order, with non-Gregorian dates translated to that calendar and conjectured dates included. Letters lacking day and month were placed at the end of the given year; those lacking only day were sequenced at the end of the given month. Originals, copies, and drafts of the same letter bear the same number. To account for a letter discovered after the initial numbering took place, the editors added an alphabetic character to the number of the letter that chronologically preceded the new one, e.g. #3a to 3f are additions that follow #3 which predates them. However, #3g comes chronologically before #3f, because it was discovered and assigned a number still later in the editorial process. Last minute discoveries were given roman numerals when they were edited in vol. 22, but because some of those letters are variants of previously numbered letters, numbers are assigned to all letters in vol. 22 in a manner similar to the earlier volumes. Likewise, unedited letters that were found are numbered according to the editors’ system.

A major anomaly of this system resulted when the editors continued their numbering to material that they appended to a letter. Hence a letter might be edited behind another that cites its results rather than in its proper chronological position; for example, a letter from Isaac Newton to Henry Oldenburg (#1956) appears behind one from Oldenburg to Huygens (#1955) that quotes it. As the example of #1956 and #1957 shows, the editors sometimes split a letter into parts, numbering each separately. Moreover, particularly in vols. 9 and 10, some appendices are not letters at all, but related manuscripts, also assigned letter numbers.

Dates – Dates are presumed to be new style unless conjectured to be old style by the addition of [o/s] or are dated as such by the correspondent. In brackets new style dates are provided to old roman versions according to de Morgan’s tables and these are translated without comment roman numerals to arabic when they were used in otherwise new style dates. Some letters from Florence are “ab Incarnazione” which means the year only is written old style and dates before March 25 should be upped by one year. Contrarily, some English correspondents gave the day and month old style but treated the year as starting in January; those hybrids are listed as o/s. If the content suggests that the letter has been misdated, the suggested correction is given in editorial brackets behind the month or year in question. For the most part, the editors’ conjectured dates have been accepted.          

Sender - Names could be spelled in a variety of ways during the seventeenth century and, hence, there is no standardized spelling for a given correspondent that is used by all of the holding libraries. Here, the spelling used in Oeuvres Complètes is used, but some names are adjusted to conform with Leiden University Library’s listings in the Catalogus Epistularum Neerlandicarum. In most cases, variants are self-evident, such as the latinized version of the name, but the researcher should be alert to possible alternative spellings. The sender and recipient of most letters can be identified from the text, even when not signed and addressed. To distinguish conjectured correspondents, the editors bracketed those names in their headers. However the editors were inconsistent. Here the brackets are left out and instead the positive indications of signature and address are recorded. In the few cases where the identity of one of the persons is truly conjectured, the name is bracketed.          

Recipient – see description above.          

Language – An abbreviation of the language is given.      

Signed - A letter is considered signed [s] if the original bears a signature, the original begins with a formal Latin greeting that includes the name of the sender, the draft is signed, or the copy includes a copy of the signature. For consistency, this rule applies to Huygens’ own drafts and letters, although they are recognizably by him. Letters are considered signed even when the signature is not unambiguous, as in the cases of the Perrault brothers, who only give their last name, and the ubiquitous “C. Huygens”, because the correspondents would have regarded them as signed.

Addressed - A letter is considered addressed [a] if the original bears the address, the original begins with a formal Latin greeting that includes the name of the recipient, the draft or summary names the recipient, or the copy includes a copy of the address. Usually a letter, especially one by Huygens, consists of a folio-sized sheet folded in half and treated as a double quarto. If the text did not continue onto the back page, the sender folded the letter in such a way that the blank page was the only part visible, sealed the bundle, and addressed it. In cases where the text covered the back page, the sender used a separate wrapper to enclose the bundle and bear the address (the equivalent of a modern envelope). Many wrappers do not survive and some could now be attached to the wrong letter, all of which influences the unambiguous identification of the recipient. Moreover, with regard to family letters, the addressee must be conjectured from circumstance. For example, Huygens de Zuylichem could be Constantijn Sr or Jr, while Huygens de Zeelem is Constantijn Jr until the death of their father

gives that title to Christiaan. And “Broer Huygens”, although considered by the sender as addressed, and listed as such below, is only identified by determining who was at home on that date.

Version – Several letter versions can be identified: Original (O)/ Draft (D)/ Summary (S)/ Copy of original (C)/ Copy of Draft (C(D))

-          Originals [O] are usually readily identifiable by their neatness, folds, seals, signatures, and/or addresses. Some problematical cases include letters written but not sent. Also, HUG 45 includes some originals written by Huygens that returned to the collection later, through purchases that were not always well documented. In the case of Frans van Schooten, Huygens himself retrieved the originals when his mentor died. Because I do not know the handwriting of each correspondent, by default this division includes copies made by amanuenses but signed and addressed to Huygens. For example, the letters of Robert Boyle and Leopoldo de’Medici are definitely written out by secretaries but are listed here as originals not copies. Also included in this division are manuscripts that the editors have reproduced as appendices to letters.

-          Drafts [D] by Huygens almost always have crossed out passages that have not been edited. Frequently they also hold unrelated material, such as calculations. The drafts by some correspondents, including Constantijn Huygens and Jean Chapelain, are in the hands of amanuenses. These are listed as drafts and not copies, because they were for the personal records of the sender. Essentially they are drafts dictated to secretaries who then copied them for sending. Also included in this division are manuscripts of poems, because they were usually rewritten neatly and sent to a recipient; for example, see #1235 where both the handwritten draft and the neat copy sent to Christiaan (the original) exist. If the language of the draft or summary differs from that of the original, it is noted in brackets.

-          Summaries by Huygens are usually a list of talking points made before composing the letter (as opposed to a synopsis made after). They are usually found either along the upper left margin of the draft or on the outside of the letter to which he is replying. Clusters of summaries can also be found on the last pages of many of the workbooks. Listed in this section are more extensive summaries that differ from drafts primarily because they refer to the recipient in the third person; for example, “that he has proved it wrong” versus “you err in presuming”. Recipients, including Huygens, sometimes underline passages as reminders for a reply or, as is probably the case with Oldenburg, a report to someone else. These are listed as summaries unless words are copied or added. Note that the editor’s categories of minute and copie are not followed.

-          Copies that were sent in lieu of handwritten originals or were saved for personal records are listed respectively as originals or drafts, as previously noted. For example, the copy of letter #200 is housed with drafts in Constantijn Huygens Sr’s hand and functions as a reminder of what was sent, hence it is called a draft. For consistency, a letter is called a draft even when the word “copie” is at the top. However, because the focus of this collection is on Christiaan Huygens, copies of his drafts and originals are listed as copies. Otherwise, letters in this division are usually intended for third parties or archives. Two primary sets of copies dominate this section: (1) those made by Constantijn Huygens Lz of the family letters (HUG 36: 1) and drafts (HUG 36: 2) then in his possession; (2) those officially recorded in the copybooks of the Royal Society of London. In the case of the Royal Society copybooks, it is sometimes difficult to determine whether the copy is of the original [C:] or of the draft [C(D):].