Coloured digital models of animals in strange shapes

Revealing Exceptional fossils, one layer at a time

Around 120 years ago, William Sollas, Professor of Geology at the University of Oxford, developed a special technique for grinding down and imaging certain kinds of fossils. Sollas was based at the Museum at the time, and the process he pioneered is still used here today, as our Palaeobiology Technician Carolyn Lewis explains to mark the anniversary of Sollas’ birthday on 30 May.

Rock face with geologists hammer
Site of the Herefordshire Lagerstätte, showing the nodules embedded in soft volcanic ash.

Here at the Museum, I work on a collection of exceptionally well-preserved fossils from the Silurian Herefordshire Lagerstätte. They were deposited on the seabed 430 million years ago when the animals were buried by a volcanic ash flow. The fossils range in size from less than a millimetre up to a few centimetres, and represent a diverse collection of marine invertebrates that includes sponges, echinoderms, brachiopods, worms, molluscs and a wide variety of arthropods.

These Herefordshire Lagerstätte fossils are unusual in that many of them have preserved soft tissues in remarkable detail, including eyes, legs, gill filaments, and even spines and antennae only a few microns in diameter. The key to this extraordinary preservation is that as the fossils developed, calcium carbonate nodules formed around them, protecting and preserving the fossils since the Silurian Period.

Usually, only the hard parts of fossil invertebrates are preserved – the carapace of trilobites or the shells of brachiopods, for example – so the Herefordshire material provides us with a great opportunity to work out the detailed anatomy of these early sea creatures.

Split rock nodule showing fossil of Offacolus kingi inside.
Close-up of the fossil of Offacolus kingi

But the problem we face is how to extract the specimen from the rock nodule without losing the information it contains. The fossils cannot be separated from the surrounding rock by dissolution, because both fossil and nodule are made mainly of calcium carbonate, so would dissolve together. And they are too delicate to be extracted mechanically by cutting and scraping away the surrounding nodule. Even high resolution CT scans cannot, at present, adequately distinguish between the fossils and the surrounding rock material.

To get round this problem we use a method of serial grinding and photography based on the technique developed by William Sollas in the late 19th century. We grind the fossils in increments of 20 microns then photograph each newly ground surface using a camera mounted on top of a light microscope. This generates hundreds of digital images of cross sections through the specimen.

Then, using specially developed software we convert the stack of two-dimensional images into a 3D digital model that can be viewed and manipulated on screen to reveal the detailed form of the animal. These 3D models are artificially coloured to highlight different anatomical structures and can be rotated through 360o, virtually dissected on screen, and viewed stereoscopically or in anaglyph 3D.

Although our method of serial grinding is still fairly labour intensive, it is far less laborious and time-consuming than the process used by William and his daughter Igerna Sollas. Compared to the photographic methods of the early 20th century, where each photographic plate required long exposure and development times, digital photography is almost instant, enabling us to grind several specimens simultaneously.

Grid of images show a fossil at different stages of grinding down
Sequential serial grinding images of an ostracod

Computer software also allows us to create 3D virtual models rather than building up physical models from layers of wax. Yet despite our modern adaptations, we are using essentially the same technique that William Sollas developed here at the Museum 120 years ago. And using this technique to study the fossils of the Silurian Herefordshire Lagerstätte has yielded a wealth of new information that opens up a unique window into the evolution and diversification of early life in our oceans.

The astounding story of the fake butterfly specimen Papilio ecclipsis – would you be fooled?

For April Fool’s Day, our Senior Collections Manager Darren Mann recounts the story of an elegantly fake butterfly – Papilio ecclipsis – asking whether it was a piece of scientific fraudulence or practical joke that went awry.

James Petiver, a 17th-century London apothecary, was renowned for having one of the largest natural history collections in the world. Petiver (1665-1718) published some of the first books on British insects and created common names for some of our butterflies.

Volume 3, Plate II of Jones Icones – the two lower images are of Papilio ecclipsis

On plate 10 of his Gazophylacium naturae et artis — an illustrated catalogue of British insects (1702) he figured a unique butterfly that “exactly resembles our English Brimstone Butterfly were it not for those black Spots, and apparent blue Moons in the lower wings”. It was given to him by his late friend and butterfly collector William Charlton (1642-1702). This butterfly was later named Papilio ecclipsis by the father of taxonomy himself, Carl Linnaeus, in his 1763 work Centuria Insectorum Rariorum, and it became known as the Charlton Brimstone or the blue-eyed brimstone.

Petiver’s collection was purchased by Sir Hans Sloane (1660–1753), who later donated his entire ‘cabinet of curiosity’ to the nation, becoming the foundation for the Natural History Museum, London, originally part of the British Museum. It was here that wine merchant and naturalist William Jones (1745-1818) examined and later figured Petiver’s specimen in his Icones, an unpublished masterpiece of some 1,500 watercolour images of butterflies.

Jones’ Icones, held in the Museum’s archive, is the subject of numerous articles and is still examined by butterfly specialists the world over. Many of the specimens figured by Jones are no longer in existence, being ravished by pests or lost over time, so all that remains of these butterflies are the painted images within.

A drawer of British butterflies from the cabinet of William Jones. The Common Brimstone butterfly is the fourth from the right on the top row

When visiting London, Danish entomologist Johann Christian Fabricius (1745-1808) studied the paintings that Jones made and described over 200 species of butterfly new to science. Fabricius also visited the British Museum where he examined Petiver’s specimen of ecclipsis. In Entomologia systematica (1793) Fabricius revealed the enigmatic ecclipsis to be no more than a painted and “artificially spotted” specimen of the Common Brimstone (Gonepteryx rhamni). So, the dark spots and blue eyes were merely artistic licence, but whose?

Iconotypes, published by Thames & Hudson, will be available from October 2021

Petiver’s specimen, seen by both Jones and Fabricus in the British Museum in the late 18th century, had mysteriously disappeared by the following century. It is said that when Dr. Gray (1748-1806), Keeper of National Curiosities at the Museum, heard of the deception he became so enraged that he “indignantly stamped the specimen to pieces.”

It is still unclear whether this was an example of scientific fraud by Charlton, or if it was intended as a practical joke that went awry.

There remain two specimens of ecclipsis in the collection of the Linnean Society. Although it is uncertain who created these, it is believed that these replicas were made by none other than our very own William Jones, as he was one of the few who had the artistic skills to undertake such work. The forthcoming publication of Iconotypes, showing Jones’ Icones in all its splendour, will hopefully demonstrate how he had both the knowledge and the skill to recreate these fascinating fakes.

Links and References
Salmon, M., Marren, P., Harley, B. (2001) The Aurelian legacy: British butterflies and their collectors. University of California Press.
The Linnean Society https://www.linnean.org/
Vane-Wright, R. I. (2010) William Jones of Chelsea (1745–1818), and the need for a digital online ‘Icones’. Antenna. 34(1), 16–21

Railway Geology part 2: Read all about it

By Nina Morgan – geologist, science writer and Honorary Associate of the Museum
Picture research by Danielle Czerkaszyn, Librarian and Archivist

The expansion of the railways in the 19th century offered more than just faster travel times. The growing rail network opened up the potential for introducing the wonders of geology, scenery and history to the travelling public at large. It also made it possible for geologists working in the field to import the comforts of home. And it spawned a new form of popular science and travel writing – describing geology and scenery from the train.

The geologist John Phillips, then based in York but later first Keeper of the Museum, was among the first to recognise these advantages. In 1841 he was on assignment mapping with the fledgling geological survey in southwest Wales. He expected the project to last several months, so rented a house in Tenby and – missing his home life – asked his sister Anne, along with Mary, her maid, and Cholo, their dog, to travel from York to Tenby join him.

Letter from John Phillips to his sister Anne, 28 April, 1841 (OUMNH Archive)

It was a marathon journey. In a long letter to Anne written on 28 April 1841, he provided her with detailed instructions about how to achieve it. Although it is clear that Phillips had become very familiar with the train timetables, he was not so sure about the rules for travelling with dogs. Two days later he wrote again to Anne to say:   

“How you will bring poor Cholo I do not even conjecture. Perhaps they will let him be with you in the carriage…. Pray have a good courage  then all will go right.”

 John Phillips’s popular railway guidebook, 2nd edition, 1855 (OUMNH collection)

Phillips’s book, Railway Excursions from York, Leeds and Hull, first published in 1853, was a popular success. It went through several editions and was republished several times under various titles.  Along with references to geology, the book included much historical background about the buildings, sights to be seen, and advice on the top ‘tourist destinations’ and how to reach them.

Phillips’s book inspired other geologists to jump onto the platform, and as new lines opened, so new railway geology guidebooks began to appear. Notable examples include the Geology of the Hull and Barnsley Railway by Edward Maule Cole, which appeared in 1886; and Yorkshire from a Railway Carriage Window, included as Part 2 in the massive Geology of Yorkshire by Percy Fry Kendall, Emeritus Professor of Geology at Leeds University, and Herbert Wroot, Honorary secretary of the Yorkshire Geological Society, which was published in 1924.

 Illustrations from Geology from a Railway Window, part 2 of The Geology of Yorkshire by Percy Fry Kendall and Herbert B. Wroot, 1924 (OUMNH collection)

Network rail

As the railway network expanded throughout Britain, so did the number of authors keen to describe the geology of their part of the country from the windows of a train. In 1878, the Geologists’ Association organised an excursion to examine the geology exposed in railway cuttings along the Banbury and Cheltenham District Railway from Chipping Norton to Hook Norton. Participants were advised to take the train from Paddington to Chipping Norton, with luggage directed to The White Hart, Chipping Norton.

In 1886, Sir Edward Poulton, later Hope Professor of Zoology at the University of Oxford, published an account of The Geology of the Great Western Railway journey from Oxford to Reading. Then in 1945, the Oxford geologist W.J. Arkell published his classic paper, Geology and Prehistory from the train, Oxford to Paddington; and in 2005 Philip Powell, a former curator and now Honorary Associate at the Museum, paid tribute to Arkell’s methods of observation by adding a final chapter outlining the geology that can be seen when travelling on part of the Cotswold Line from Moreton in Marsh to Reading, to his 2005 book, The Geology of Oxfordshire.

Meanwhile, the geologist Eric Robinson, now retired from University College London, prepared numerous handouts for his students and amateur guides describing the geology that can be seen from trains leaving from various London stations.

Times past

Along the way all of the ‘railway geologists’ painted vivid pictures both of the geology and the countryside as they saw it, and their descriptions – especially those from the earlier publications – provide a valuable insight into landscapes and railway lines now lost.

“A railway tour is life in a hurry,” Phillips proclaimed in his pioneering railway book. He clearly enjoyed the rush, and so did the many other geological authors and lovers of the countryside who followed in his tracks. Even today, with a railway geology book in hand, those delays along the line can turn into a real pleasure – depending where you’re held up, of course!

Railway Geology Part 1: The flying steed

By Nina Morgan – geologist, science writer and Honorary Associate of the Museum
Picture research by Danielle Czerkaszyn, Librarian and Archivist

The introduction and growth of the railway network in the first half of the 19th century not only revolutionised travel and transport of goods for many, but it also had a profound effect on the science of geology.  Not only did it make it easier for geologists to cover the ground quickly – but the railway cuttings for the new lines revealed rock outcrops that had never before been seen.

John Phillips as a young man

One of the first to take advantage of the new possibilities was John Phillips (1800–1874), the first Keeper of the Museum, and nephew of William Smith, often referred to as the Father of English Geology. Phillips was orphaned at the age of eight, along with his younger sister Anne, and their younger brother, Jenkin.

John was educated at Smith’s expense and learned about geology at his uncle’s knee. He was reunited with Anne in 1829.  Neither married and they lived together until her death, with Anne serving as John’s housekeeper, moral support, confidant and geological companion. John went on to become a skilled palaeontologist, field geologist and prolific author.  He also became a great train enthusiast.

Anne Phillips photographed in 1860
(© Royal Institution London)

On 23 July 1835, John wrote to Anne with this vivid description of his first train journey – travelling on a ‘flying steed of Iron,’ from Manchester to Liverpool on his way to Dublin.

“…My dear Annie, You must certainly come to feel the strange impression of this flying Steed of Iron. It does so hurry & flurry on, you shake & sleep & start & wonder at the gliding Houses, trees & Churches, — the trains which meet & pass you’ like the swiftest birds with a rushing sound & the Master power (Steam) & a confused picture of colours & forms not at all distinct as Men[,] Women, Carriages &c that it is all like magic & can not be understood by a mere description. Then you are dragged through a tunnel full of gas lamps, then laid hold of by ruffian porters & crammed into an Omnibus whether you will or no & whirled away the man who guides (only) knows whither. “

Phillips quickly became a convert to train travel. He was often travelling from his then base in York to earn money by giving lecture courses by subscription to members of the various newly formed Philosophical societies, so enjoyed the relative convenience and faster travel times railways offered – even though, as he wrote to Anne in March 1841, the trains were not always punctual. 

Black and white image of railway station  on postcard.
Liverpool and Manchester Railway commemorative postcard
(author’s collection)

“I found the Train of yesternight very good travelling till we entered on the Leeds & Manchester line at Normanton. Then began this singular amusement: to lose time so as to arrive in 4 hours from Leeds, the time really required being 2 1/2 hours.  We did this odd railway feat by stopping 5 minutes each at about 10 stations & using all possible precautions not to go too fast.  This is said to be on account of the recent embankments not allowing of rapid transit: but some of the trains are faster. We reached Manchester at 10:30, that is to say in 4 hours from York.”

Sound familiar?!

Scan of handwritten letter.
Letter from John Phillips to his sister Anne, 30 March 1841 (OUMNH Archive)

In the second part of Railway Geology, Nina will take a look at how the expansion of the railway network spawned a new form of popular science and travel writing.

Crunchy on the outside

By Susie Glover, HOPE Learning Officer

We have an ambitious project underway at the Museum, to preserve a unique and scientifically important collection of over one million British insects. It’s called HOPE for the Future, after the Hope Entomological Collections, and we are keen to shout about how these specimens can help us understand biodiversity, habitats and ecologies.

The learning team behind the project are today launching a new blog for young people interested in entomology. Intriguingly, it’s called Crunchy on the Outside, but please don’t confuse this with the similar, but fundamentally different, mid-’90s advertising campaign for the Dime bar.

A high magnification image of an insect, face-on, showing large proboscis and brown body.
One of many weird and wonderful specimens from our collection, the Acorn Weevil (Curculio glandium).
Here is a peek at some of the tools of the trade, used to move and mend specimens like this moth.

Crunchy will be crammed full of interesting insect info, fun things to make and do, a peek behind the scenes at the Museum, and news from people, past and present, who work in the field of entomology. The odd bad joke may also worm its way in (What do butterflies sleep on? Cater-pillows).

The blog will also be a platform for young people to have their say, about the topics covered on Crunchy itself, as well as on the activity of the Museum. It will give them first dibs on access to related events too. You can check it out, follow, and share at crunchyontheoutside.com.

HOPE for the Future is funded by the National Lottery Heritage Fund.

Wax models of magnified mites mounted on a black board

Of parasites, dinosaurs, and other model animals

Elaine Charwat has been on a journey into the attic storerooms behind the scenes of the Museum to discover 19th-century wax models of parasites. A strange occupation you might think, but it’s all part of her doctoral research programme with the Arts and Humanities Research Council to learn about the use of models and replicas in science, past and present. In the podcast above Elaine meets Mark Carnall, Zoology Collections Manager at the OUMNH, who talks about the differences between models and the thousands of specimens he looks after, and Dr Péter Molnár, Assistant Professor of Biological Sciences at the University of Toronto, who offers important insights into current research using mathematical models.

Different types of models and replicas are everywhere in the Museum, and they tell us much about the organisms they represent or reconstruct, but even more about processes in research and science. Made to communicate and produce data, these larger-than-life objects are as fascinating as their subjects…

Top image: Wax models of Sarcoptes scabiei (itch mite) produced by Rudolf Weisker, Leipzig (Germany), probably late 1870s or early 1880s. These models are listed as having been on public display at the Museum in 1911, labelled: “Sarcoptes scabiei: enlarged wax models, male & female + mouth parts”.