The record behind the sheet in your tube: the file we worked from, what we measured, what we chose and why, what we are allowed to sell, and the framing dimensions for this sheet.
Framing this sheet
- 40 × 50 cm sheet
- A 40 × 50 cm frame, no mat. Nearest standard 16 × 20 in. Margins 8.41 cm each side, 7.34 cm above, 8.44 cm below.
- 50 × 70 cm sheet
- A 50 × 70 cm frame. Nearest standard 20 × 28 in. Margins 10.51 cm each side, 12.66 cm above, 14.56 cm below.
- If you mat it
- Go one frame size up and cut the window three millimetres inside the printed image on every side: 22.59 × 33.62 cm for the small sheet, 28.39 × 42.18 cm for the large one. Off-white or warm white board, acid-free. Do not trim the sheet.
The sheet you have
- Work
- Franz Michael Regenfuss (German, Nuremberg 1712–1780 Copenhagen), Plate III from Auserlesne Schnecken, Muscheln und andre Schaalthiere / Choix de Coquillages et de Crustacés, 1758, after a drawing by Gabriel Müller
- Object
- Hand-coloured engraving. Printed area 27.34 × 41.13 cm, reproduced with its paper margin at 28.99 × 42.78 cm, in a folio printed at Copenhagen by Andreas Hartwig Godiche under royal privilege
- Held by
- Zentralbibliothek Zürich, from the library of the Naturforschende Gesellschaft in Zürich
- Inventory
- NF 87 | F · DOI 10.3931/e-rara-51596
- Rights
- Public Domain Mark. The library publishes the volume freely and asks, in the usual scholarly form, to be cited
- File
- Zentralbibliothek Zürich through e-rara, at high resolution, taken directly from the institution and not from an aggregator
- Crop
- [941, 932, 4565, 6737] in the page file — x, y, width, height — that is 4565 × 6737 px: the ink boundary of the printed area plus 130 px of paper on every side, confirmed by eye at roughly five times print size. Corrected on 17 September 2026: the first crop was set too tight and ran through TAB. III at the head. Print files, gallery images and the figures on this page were all rebuilt from the corrected one
The plate
A textile cone stands in the middle of the sheet, its shell covered edge to edge in a net of small white triangles on brown. Around it a ring of smaller shells: a rose-flushed cockle at the top, two yellow thorny oysters left and right, a deep red scallop at the foot, cones and top shells filling the field between.
It is the quietest of the twelve plates — far more paper than shell. Regenfuss was not arranging his shells by species but by symmetry, the way a cabinet keeper arranged a drawer, and on this sheet he left the arrangement more air than anywhere else in the book.
How the book was made
Regenfuss began planning an illustrated book on shells and crustaceans in Nuremberg as early as 1745 and could not finance it. He finally realised it in Copenhagen in 1758, under the patronage of Count Adam Gottlob von Moltke, who kept a famous shell cabinet of his own and had Regenfuss appointed engraver to the Danish king. The drawings are by Gabriel Müller, the engraving is Regenfuss's own, and the colour was applied by hand — most of it, contemporaries record, by his wife Margaretha Helena. The book was celebrated at once for the unusual size of its plates and for the almost three-dimensional effect of the colouring.
Why 400 dpi, and how we know
The library's scan carries no stated resolution, so we took it from the file itself. The JFIF density in the delivered JPEG reads 400 × 400 dpi at every derivative size we requested — which means the value is inherited from the master and does not describe the derivative. Cross-checked against the object: the page measures 6609 × 8778 px between its own edges, which at 400 dpi is 41.9 × 55.7 cm. A folio, exactly as catalogued.
At that density the plate carries 400 dpi when printed at original size, so the 50 × 70 cm sheet is a true 1:1 print with reserve above our 300 dpi floor. The 40 × 50 cm sheet prints it at 0.80×, where 500 dpi are available.
What we measured at the edges
The Zurich copy is bound, and that has one consequence we will not hide. The gutter side of the page curves away from the lens, so the left-hand edge of the plate is foreshortened. Measured against the flat, unbound Metropolitan Museum copy of the companion sheet — Plate IV, 2019.282.20, platemark catalogued 42 × 29.5 cm — our plate reads about 1.4 cm narrow, while the height agrees to within one per cent.
The picture itself is barely affected. On Plate IV the large scallop at the centre measures exactly square in both copies, 1.000 against 0.999, so the compression sits in the gutter margin and in the outermost left-hand shells, of the order of three per cent. We document that and leave it. Stretching the file to close the gap would be inventing a measurement, and it is not our business to correct a 268-year-old book for being bound.
A second check, run after the crop was corrected: every edge of the crop was scanned at a grey threshold of 175 for the first ink coming in from the paper. Over any run longer than five pixels the nearest ink lies at least 120 px — 0.76 cm — inside the edge. Nothing of the engraving or the lettering is touched. The single darker pixels closer to the edge are foxing and paper fibre, and they stay, like everything else on this paper.
What we are allowed to sell
Regenfuss died in 1780 and Müller in the same century; the engraving has been in the public domain everywhere we ship for two centuries by any term that has ever applied. At the reproduction level the Zentralbibliothek Zürich publishes the volume through e-rara under the Public Domain Mark and states that it is free to download, asking in the usual scholarly form for a citation naming author, holding institution and persistent identifier. That citation is carried here and on the product page. Markets checked: Switzerland, the EU, the United Kingdom, the United States. Clear in all four.
A note on choosing
The large sheet is the plate at the size Regenfuss printed it, and that size was the point — his contemporaries said so. The small one is the same picture for a narrower wall, at four fifths. This is the calmest of the three Regenfuss sheets in this catalogue; it hangs well beside the other two, and on its own it is the one that does not raise its voice.