Stephen J Jenkins
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jnknssj.bsky.social
Stephen J Jenkins
@jnknssj.bsky.social
1.1K followers 800 following 350 posts
Professor at Cambridge University, Fellow of St Edmund's College, Student of Everything Else. Posting in a personal capacity; opinions and photographs my own.

www.ch.cam.ac.uk/person/sjj24
orcid.org/0000-0001-9362-9665
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Bit of a cheat for #RomanFortThursday this time, with a section of wall from Isca Dumnoniorum (Exeter). Built around CE 200, the city wall shown here encloses a rather larger area than the original wooden-walled legionary fortress of CE 55. #Archaeology #RomanWall #RomanBritain #Exeter #Photography
Photograph of a stretch of wall, two or three metres in height, running from the right foreground to the left middle distance, with grass in front. A tree stands at the left of frame, on this side of the wall. In its closest section, the upper two thirds of the wall are of original roman construction, comprising rectangular purple stones of volcanic origin (Rougemont Trap) laid in regular courses. The lower section represents later underpinning (the ground level having been lowered) in a red coloured stone (Heavitree Stone) and is of a much rougher and more irregular construction. Further away, closer to the tree, the roman work has been replaced or patched with medieval masonry comprising a rather random assemblage of smaller stones.
November 27, 2025 at 1:24 PM
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"Remains of Eastern Defences, King's Castle, Wiveliscombe" from Ancient Earthworks & Camps of Somerset (Edward J. Burrow, 1924). #HillfortsWednesday #Archaeology #Prehistory #Watercolour #Monochrome #BlackAndWhite #Wiveliscombe #Somerset
Monochrome watercolour depicting a pathway leading away from the viewer between two earth ramparts. The ground slopes from left to right and is lightly wooded.
November 26, 2025 at 10:56 AM
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Oceanus, in the Alcazar de los Reyes Cristianos, Cordoba. #MosaicMonday #Archaeology #Mythology #Photography
Photograph of a mosaic depicting the head of the Titan Oceanus. He has a droopy moustache, a pointy beard, and appears to have an octopus and crab claws emerging from his long shaggy hair. He is surrounded by marine life, including fish and what may be shrimps.
November 17, 2025 at 11:13 AM
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Arms (possibly subtly erroneous) of William Keith, 2nd Earl Marischal of Scotland. Stained glass in the Great Hall of Stirling Castle. Argent a chief paly of six or and gules. #Heraldry #Stirling #Scotland #StainedGlassSunday #Photography
A photograph of heraldic stained glass. A central shield is surmounted by a golden coronet and surrounded by a circular golden halo decorated with stylised fronds and small saltire-bearing roundels. The shield is largely white, save for a band of six vertical stripes, alternating gold and red, occupying its upper third. Outside the halo is a regular diamond pattern of plain glass.
November 16, 2025 at 10:21 AM
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Doorways - Pueblo Bonita, Chaco Canyon, New Mexico. #ChacoCanyon #NewMexico #Archaeology #Architecture #Photography
Photograph showing a series of doorways receding into the distance, each within the frames of the closer ones. The doorways are rectangular and open into mortarless walls constructed from densely-stacked thin stones of a light honey colour.
November 15, 2025 at 11:27 AM
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Two views of a Common Darter. #Dragonfly #FlyDay #Insects #Bugs #Nature #Wildlife #MacroPhotography #Photography
A red dragonfly perches upon a rock in three-quarter profile, facing toward the viewer's left and illuminated by strong sunlight. Its wings are spread and its front legs are slightly raised. The rock is rough and mainly light brown with patches of white, hosting a small growth of lichen on its shady side. In the background can be seen assorted foliage in soft focus. Extreme close-up of a red dragonfly in left-facing three-quarter profile, perching upon a rock in strong sunlight. Its eyes and body dominate the image, while its wings extend beyond the frame on both sides. Its front legs are slightly raised and individual spines can be distinguished along their length. The surface of the rock is rough and its colour is light brown. Behind, foliage is defocussed to the point of abstraction, forming a light green backdrop to contrast dramatically with the insect's coluration.
November 14, 2025 at 12:25 PM
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Remains of a military bathhouse of the mid-Severan period, Vindolanda, Northumberland. #RomanFortThursday #Vindolanda #RomanBritain #Archaeology #Monochrome #BlackAndWhite #Photography
Black and white photograph showing the ruins of a roman military bathhouse. Walls stand several courses high, surrounding an open area that would once have formed part of the hypocaust system. A number of pillars still stand, but the floor they would have supported is missing. Beyond the building, in the distance, is a landscape of grass and occasional trees. The sky above is a featureless white expanse.
November 13, 2025 at 1:57 PM
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"The immense stone rampart of Dolebury Camp, at the North-East angle" from Ancient Earthworks & Camps of Somerset (Edward J. Burrow, 1924). #HillfortsWednesday #Watercolour #Dolebury #IronAge #Somerset
Monochrome watercolour showing a massive stone rampart at left, separated by a ditch from a lesser rampart toward the lower-right of frame. In the distance, fields lead down to the Bristol Channel, beyond which is glimpsed the coast of South Wales. The sky appears laden with cloud.
November 12, 2025 at 10:32 AM
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Rainbow over Loch Leven, Ballachulish. #Rainbow #LochLeven #Highlands #Scotland #Photography
Snatched photograph of a rainbow hovering low over a sea loch. In the foreground are trees, in the midground two sailboats on the loch, and in the distance grassed and wooded hills. The rainbow stands out brightly against the latter. Above, the sky is an ominous grey.
November 11, 2025 at 11:20 AM
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Eros & Psyche, in the Alcazar de los Cristianos Reyes, Cordoba. #MosaicMonday #Archaeology #Mythology #Photography
Photograph of a mosaic depicting two mythological figures embracing. The figure on the left (Psyche) is female and faces away from the viewer, wearing a rather diaphanous dress. She seems to have delicate butterfly-like wings emerging from her upper back. The figure on the right (Eros) is naked apart from a parted cloak and faces toward the viewer. He sports a pair of large bird-like wings on his back. The colour palette includes flesh tones, white, black, and various golden brown hues.
November 10, 2025 at 12:27 PM
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Arms of Patrick Hepburn, 1st Earl of Bothwell. Stained glass in the Great Hall of Stirling Castle. Quarterly, 1 & 4 Or a bend azure (Vaus); 2 & 3 Gules on a chevron argent two lions passant gules pulling at a rose of the same (Hepburn). #Heraldry #Stirling #Scotland #StainedGlassSunday #Photography
A photograph of heraldic stained glass. A central shield is surmounted by a golden coronet and surrounded by a circular golden halo decorated with intertwined studded belts and small roses. The shield is divided into quarters, the upper-left and lower-right of which each display a blue diagonal stripe, running from upper-left to lower-right, on a gold background. The upper-right and lower-left quarters each feature a red background with a white chevron, upon which two red lions in passant posture approach a single red rose from either side. Outside the halo is a regular diamond pattern of plain glass.
November 9, 2025 at 10:45 AM
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Cliff Palace, Mesa Verde National Park, Colorado. #MesaVerde #Colorado #Archaeology #Architecture #Photography
Photograph of semi-ruined dwellings nestling beneath an overhanging cliff. The buildings are constructed from honey-coloured stone, comprising houses, towers, and courtyards. They run from lower-left of frame toward the mid-right, where they are obscured by foreground foliage. The massive overhanging cliff is of similar colour to the buildings, looming over them in a manner that somehow seems both protective and threatening. At the top-right of frame, a patch of sky is largely filled by bright white clouds with small glimpses of blue between them.
November 8, 2025 at 12:54 PM
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Exactly a year since I stopped tweeting and fully committed to this place. So much nicer over here.
A seagull soars in a cloudless blue sky, its wings tipped with black but otherwise pure white. The gable end of my parents' roof encroaches into the bottom of frame.
November 7, 2025 at 9:16 PM
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Bluebottle. #FlyDay #Insects #Bugs #Nature #Wildlife #MacroPhotography #Photography
Photograph of a bluebottle fly sitting on a waxy green leaf. The fly has an iridescent greenish body and red eyes. Its wings are held back, slightly away from its body. The fly and its leaf are in sharp focus, occupying between them the lower right of frame. The background comprises foliage in very soft focus.
November 7, 2025 at 12:49 PM
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North Gate of Housesteads Fort, Northumberland. #RomanFortThursday #Housesteads #HadriansWall #RomanBritain #Archaeology #Monochrome #BlackAndWhite #Photography
Black and white photograph of a roman gateway at Housesteads Fort. The bases of two square towers remains, up to a height of four or five courses of squared-off stone. A stone cistern can be seen in front of the left-most tower. Between the towers, a wide opening is punctuated by a central stone pier of square cross-section. The double pathway that it creates is grassed over, as is the land both inside and outside the gate. The wall of the fort, again about four or five course in height, extends on either side of the gateway. In the distance, Hadrians Wall runs in a north-easterly direction toward the leftmost edge of a patch of woodland that occupies the mid-right of frame. Further away, there is another wooded area just above centre-frame, standing in expansive grassland. The sky is mainly clear, but decorated with light cloud.
November 6, 2025 at 12:58 PM
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Arms of Sir Malcolm MacGregor, 5th Baronet MacGregor, in St Conan's Kirk, Loch Awe. Argent an oak tree eradicated in bend sinister proper, upon which a sword bendwise azure supporting on its point a crown gules. For the crest, a lion's head proper crowned or. #Heraldry #Woodcarving #Photography
Wooden carving of a coat of arms belonging to Sir Malcolm MacGregor, 5th Baronet MacGregor. The shield bears an uprooted oak tree, tilted such that its roots are lower left and its branches upper right. Across this lies a sword, its pommel at lower right and its point at upper left. The point of the sword supports a crown with five visible spikes. The whole shield is tilted at 45 degrees clockwise from vertical, and carved drapery artfully crosses its lower portion. Above the shield is a jousting helm, surmounted by a crest comprising, in profile, a lion's head wearing a crown similar to that depicted on the shield. The background is adorned with pinecones and the name MacGregor of Glen Strae is displayed prominently at the bottom of the carving.
November 5, 2025 at 1:12 PM
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Brent Knoll, from Ancient Earthworks & Camps of Somerset (Edward J. Burrow, 1924). #HillfortsWednesday #Watercolour #BrentKnoll #Somerset #NorthSomerset
Black and white watercolour of a conical hill. The base of the hill is wooded, but the top is bare with hints of earthworks; a tall mast juts from the summit into a lightly clouded sky. In the foreground, a lane crosses the frame from lower-left toward mid-right. A few houses and a barn cluster near the foot of the hill, one cottage being particularly prominent toward the right of frame.
November 5, 2025 at 11:51 AM
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Autumn and Winter, from the Eros & Psyche Mosaic in the Alcazar de los Cristianos Reyes, Cordoba. #MosaicMonday #Autumn #Winter #Archaeology #Mythology #Photography
Photograph of a mosaic depicting Autumn in the form of the head and shoulders of a man, looking toward us and to the right. He wears a white tunic on his body and a brown-and-white garland on his head. His face and the background are largely brown and beige. Photograph of a mosaic depicting Winter in the form of the head and shoulders of a woman, looking toward us and to the left. She is wearing a white snood-like garment, adorned with a wreath picked out in blue. Her face and the background are largely brown and beige.
November 3, 2025 at 11:42 AM
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Arms of James Stewart, Duke of Ross. Stained glass in Stirling Castle. Quarterly, 1 & 4 Or a lion rampant gules within a double tressure flory-counterflory of the same (Scotland); 2 Gules three lions rampant argent (Ross); 3 Or three piles gules (Brechin). #Heraldry #StainedGlassSunday #Photography
A photograph of heraldic stained glass. A central shield is surmounted by a golden coronet and surrounded by a circular golden halo decorated with leaves. The shield is divided into quarters. The upper-left and lower-right of these each display a gold background upon which is found a red lion in rampant posture within a double-border pierced by fleurs-de-lys in the same colour. The upper-right quarter displays three white lions in rampant posture upon a red background. The lower-left quarter shows three red isosceles triangles, meeting at the top and pointing straight down, upon a gold background. Outside the halo is a regular diamond pattern of plain glass.
November 2, 2025 at 10:28 AM
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An Elegant Dismount. #Seagull #Bird #Wildlife #Nature #Seaside #Monochrome #BlackAndWhite #Photography
Black and white photograph of a seagull, wings extended but pulled back, legs outstretched, leaping from the top of a street rubbish bin, heading down toward the lower right of frame. The bird is white, apart from black markings at the very tips of its wings. In the background, in soft focus, is a whitewashed stone building with a black door and other less identifiable features.
November 1, 2025 at 1:38 PM
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Jackdaw and Buttercup. #Jackdaw #Corvid #Cawmmunity #Bird #FlyDay #Wildflower #Wildlife #Nature #Halloween #BirdPhotography #Photography
Photograph of a jackdaw, occupying the right-hand side of the frame and looking our-of-frame in that direction. Only the upper half of the bird is visible, presenting its back to us, with its head in profile. Its wings are black with brown highlights; its neck is streaked with a mass of narrow white feathers overlaid on black; and its head and beak are pure black. The bird's right eye is a piercing white with a small black pupil. In the left half of the frame, a single bright yellow buttercup is seen in soft focus at the top of a branched stem. The background of the photograph is a landscape, defocused to the point of abstraction and appearing as three hazy horizontal stripes - the lower being a light grass green, the middle a darker woodland blue-green, and the upper a white-grey sky.
October 31, 2025 at 11:33 AM
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Remnants of a Hypocaust. #RomanFortThursday #RomanBritain #Hypocaust #Architecture #Photography
Photograph showing the remains of a hypocaust at Chesters Roman Fort. In sharp focus in the foreground, two stone flagstones are supported by a set of pilae (stacks of reddish tiles) a few feet in height. Behind, in softer focus, is a partially intact wall comprising squared-off stone blocks, complete to several courses at right of frame, diminishing toward the left. Between and behind these structures, we see green grass on gently rising ground.
October 30, 2025 at 2:03 PM
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Anatomy of a Reaction. #ChemSky #CompChemSky #DFT #MolecularDynamics #Fluorine #Silicon
Rendering of a trajectory calculated, using first-principles density functional theory, for the reaction of fluorine with a hydrogen-passivated silicon surface, summarising in a single image the motion of atoms over a little more than a picosecond. The surface here is represented schematically as a simple grey plane at the bottom of frame. Two bright green traces approach it in parallel from the top of frame, representing a pair of fluorine atoms bound together as a diatomic fluorine molecule. Their paths initially wiggle in sync with each other, indicating that the molecule is vibrating. When they reach the surface, these traces diverge and become entangled with a white trace that represents just one of the many hydrogen atoms that cover the surface. Ultimately, one of the fluorine atoms replaces this particular hydrogen atom on the surface, while the other fluorine atom departs from the surface entirely, taking the hydrogen atom with it. The molecule of hydrogen fluoride thus created is revealed by a single green fluorine trace heading from the surface toward the upper-right of frame, while the white hydrogen trace spirals in the same overall direction. The molecule's rotation and vibration gives rise to an attractive five-pointed star pattern as the white trace dances around the green.
October 29, 2025 at 11:32 AM
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Durham Cathedral from the Weir on the Wear. #Durham #Cathedral #Mill #Architecture #River #Monochrome #BlackAndWhite #Photography
Black and white photograph of Durham Cathedral from the left bank of the River Wear. In the right foreground, a weir crosses the river diagonally, leading the eye to an old fulling mill that stands on the far bank. This is a handsome three-storey building with ptiched roof, set amongst thick woodland. The cathedral itself stands on the hill above and behind the mill, a pair of towers at its west end occupying the centre of frame and facing to the viewer's left. The cathedral's central tower is visible further to the right. The sky is lent interest by wispy clouds.
October 28, 2025 at 12:25 PM
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Interested in the symmetry of two-dimensional periodic patterns? There's a brief introduction to the topic in my book on the Foundations of Surface Science (OUP, 2023). #SurfaceScience #ChemSky
Photograph of a reasonably priced paperback textbook entitled Foundations of Surface Science, authored by Stephen J Jenkins and published by Oxford University Press. The cover is mainly white, with a bright orange and blue scanning tunnelling microscopy image of alanine molecules on a copper surface. The book rests at a jsunty angle on a black background.
October 27, 2025 at 11:38 AM