During the very late 19th century and all through the 20th and 21st century -- up until quite recently-- almost all printing was done by photo mechanical means. During this era increasingly complex and high speed presses and film based cameras were developed to print books, newspapers, magazines and everything else in bigger, faster and cheaper press runs.
On the graphic side the half tone dominated the reproduction of images. Half tones are an ingenious way of simulating graduations of tone by means of dots. The dots are the giveaway that it’s printed by photo offset.
When you see the dots in an image you know right away the image is almost certainly 20th century and it’s made by a photo mechanical method.
Caveat
There are lots of quality small press run books printed by photo offset and there is some exceptionally high quality printing of photographs and art work done by this method using half tones. It doesn’t mean they’re not nice books, and it doesn’t mean they are not rare, scarce and valuable books, prints or maps. But if you see the dots it does mean that they may well be modern reproductions of older works.
Screen Printing
You’re not going to see much screen printing of books, but you may see some screen printing of posters and ephemera. Most especially you’ll see sought after screen printing during the mid-20th century when a lot of the posters, t-shirts and other items associated with popular culture were made by this process.
Some of these things have become expensive and hard-to-find. If you ripped a vivid poster for a Grateful Dead concert off a telephone pole in San Francisco or waved a printed banner during a Viet Nam era anti-war rally, chances are good it was a screen print. Screen printing in the mid-20th century was often short run. . It was the technique of choice for the underground because it was cheap, easy and most often done in the garage after hours. More recent screen printing is an entirely different animal. It can be done in vast quantities and on practically any surface.
Sotheby’s, Dec. 11: Darwin and Wallace. On the Tendency of Species to form Varieties..., [in:] Journal of the Proceedings of the Linnean Society, Vol. III, No. 9., 1858, Darwin announces the theory of natural selection. £100,000 to £150,000.
Sotheby’s, Dec. 11: J.K. Rowling. Harry Potter and the Philosopher's Stone, 1997, first edition, hardback issue, inscribed by the author pre-publication. £100,000 to £150,000.
Sotheby’s, Dec. 11: Wolfgang Amadeus Mozart. Autograph sketchleaf including a probable draft for the E flat Piano Quartet, K.493, 1786. £150,000 to £200,000.
Sotheby’s, Dec. 12: Hooke, Robert. Micrographia: or some Physiological Descriptions of Minute Bodies made by Magnifying Glasses. London: James Allestry for the Royal Society, 1667. $12,000 to $15,000.
Sotheby’s, Dec. 12: Chappuzeau, Samuel. The history of jewels, first edition in English. London: T.N. for Hobart Kemp, 1671. $12,000 to $18,000.
Sotheby’s, Dec. 12: Sowerby, James. Exotic Mineralogy, containing his most realistic mineral depictions, London: Benjamin Meredith, 1811, Arding and Merrett, 1817. $5,000 to $7,000.
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Swann Maps & Atlases, Natural History & Color Plate Books December 9, 2025
Swann, Dec. 9: Lot 156: Cornelis de Jode, Americae pars Borealis, double-page engraved map of North America, Antwerp, 1593.
Swann, Dec. 9: Lot 206: John and Alexander Walker, Map of the United States, London and Liverpool, 1827.
Swann, Dec. 9: Lot 223: Abraham Ortelius, Typus Orbis Terrarum, hand-colored double-page engraved world map, Antwerp, 1575.
Swann Maps & Atlases, Natural History & Color Plate Books December 9, 2025
Swann, Dec. 9: Lot 233: Aaron Arrowsmith, Chart of the World, oversize engraved map on 8 sheets, London, 1790 (circa 1800).
Swann, Dec. 9: Lot 239: Fielding Lucas, A General Atlas, 81 engraved maps and diagrams, Baltimore, 1823.
Swann, Dec. 9: Lot 240: Anthony Finley, A New American Atlas, 15 maps engraved by james hamilton young on 14 double-page sheets, Philadelphia, 1826.
Swann Maps & Atlases, Natural History & Color Plate Books December 9, 2025
Swann, Dec. 9: Lot 263: John Bachmann, Panorama of the Seat of War, portfolio of 4 double-page chromolithographed panoramic maps, New York, 1861.
Swann, Dec. 9: Lot 265: Sebastian Münster, Cosmographei, Basel: Sebastian Henricpetri, 1558.
Swann, Dec. 9: Lot 271: Abraham Ortelius, Epitome Theatri Orteliani, Antwerp: Johann Baptist Vrients, 1601.
Swann Maps & Atlases, Natural History & Color Plate Books December 9, 2025
Swann, Dec. 9: Lot 283: Joris van Spilbergen, Speculum Orientalis Occidentalisque Indiae, Leiden: Nicolaus van Geelkercken for Jodocus Hondius, 1619.
Swann, Dec. 9: Lot 285: Levinus Hulsius, Achtzehender Theil der Newen Welt, 14 engraved folding maps, Frankfurt: Johann Frederick Weiss, 1623.
Swann, Dec. 9: Lot 341: John James Audubon, Carolina Parrot, Plate 26, London, 1827.
![<b>Sotheby’s, Dec. 11:</b> Darwin and Wallace. On the Tendency of Species to form Varieties..., [in:] <i>Journal of the Proceedings of the Linnean Society,</i> Vol. III, No. 9., 1858, Darwin announces the theory of natural selection. £100,000 to £150,000.](https://ae-files.s3.amazonaws.com/AdvertisementPhotos/00d5fd41-2542-4a80-b119-4886d4b9925f.png "<b>Sotheby’s, Dec. 11:</b> Darwin and Wallace. On the Tendency of Species to form Varieties..., [in:] <i>Journal of the Proceedings of the Linnean Society,</i> Vol. III, No. 9., 1858, Darwin announces the theory of natural selection. £100,000 to £150,000.")
