Swansea: Rainbows and Colour

Last week, Thursday 23rd and Friday 24th November, Ordered Universe members were made very welcome at the Centre for Medieval and Early Modern Research, and the Department of History at Swansea University.  Continue reading

Illuminating Colour: A Guided Tour

1P5B8805For those that haven’t yet managed to get to the National Glass Centre in Sunderland, we have here a guided tour to the exhibition by Cate Watkinson and Colin Rennie. Rosie Reed Gold took the photographs, adding another level of interpretation to the movement from 13th century Latin manuscripts, to editions and translations, to textual analysis (by Continue reading

Building Bridges, Connecting Arcs

A post by Joshua Harvey, D.Phil. student, Department of Engineering Science and Pembroke College, University of Oxford, funded by the Andrew W. Mellon Foundation as part of ‘The Mental and Material Laboratories of Medieval Science’ project, under the aegis of the Ordered Universe.

Parry Arc
Halos featuring a Parry arc – photograph by Martina Wisotzki

The latest research article from the Ordered Universe project: “Bow-shaped caustics from conical prisms: a 13th Century account of rainbow formation from Robert Grosseteste’s De iride” is available to read now, open access at the Optical Society of America’s journal Applied Optics. Grosseteste’s treatise De iride [On Rainbows], which may be familiar to long-term followers of the Ordered Universe project, explores theoretical optics, colour theory, and meteorology to give one of the most comprehensive pre-renaissance scientific writings on the rainbow. With this most recent article, we explore his pioneering model of rainbow formation – the first to use refraction (and not just reflection) in medieval Europe. Through an interdisciplinary combination of historical review, geometric optics, and both practical and simulated experiment, we give a thorough overview of the historical significance of the De iride, and look at what lessons we can learn from it today.

This fruitful exploration has not been done before. Although Grosseteste provides a detailed description of what he believes are the geometric underpinnings of a rainbow, he has previously been disregarded in this area. David Lindberg even went so far as to say that ‘his theory of the rainbow could not account for even the most basic phenomena and has remained largely unintelligible to the modern day.’ Well, we thought there might have been more to Grosseteste’s thought than that, being familiar with his mathematical mind and keen curiosity about the natural world. As a research team with a diverse expertise, we together arrived at an interpretation of Grosseteste’s optical mechanism that was intelligible, elegant and, most excitingly, perfectly testable. To our surprise, the caustics – patterns of gathered light – produced by a transparent cone are just as Grosseteste describes.

Remarkably, we have already been contacted by researchers investigating atmospheric optics, who have found some striking correspondences between their own work and our interpretation of Grosseteste’s De iride. Markus and Sarah Selmke’s recent paper, “Artificial circumzenithal and circumhorizontal arcs” published in American Journal of Physics, explores to great depths the kinds of refractive optical interactions between transparent cones, as modelled by glassware filled with water, and incident light. The authors have shown that Parry arcs, a type of halo, are analogous to the caustics produced by shining light through a wine glass of water. Although not as frequently observed as rainbows, Parry arcs are similarly beautiful displays of dispersive colour seen in the heavens, providing certain atmospheric conditions are met. The paper features a combination of practical and mathematical experimentation, similar to our own approach in the Applied Optics paper, and states that “light entering through the top air-water interface and leaving through the lateral cone surface results in an analogy to Parry’s halo”. This is identical to Grosseteste’s geometric scheme, as we interpreted it. Although, to his detractors, his likening of a rainbow to that of light going through a transparent cone might sound crude, or even ridiculous, it appears this simple model does indeed capture the optical principles behind a dispersive atmospheric phenomenon.

Grosseteste was wrong about rainbows. Not long after him, rainbows were correctly understood to be produced by light interacting with near-spherical raindrops, by both Kamal al-Din al-Farisi and Theodoric of Freiburg in the fourteenth century. But Grosseteste was not wrong about the optical qualities of transparent cones, and although the optical scene he describes in De iride does not relate to rainbows, it is analogous to another kind of dispersive optical event seen in the heavens.

Of course, it would be incorrect to claim that Grosseteste had solved the mystery of Parry’s arc back in the thirteenth century. He had probably never seen or heard of one, as they are rare outside the Arctic circles, and it wasn’t until 1820 that William Parry observed and drew one. Was this mere coincidence, could Grosseteste have happened upon an atmospheric optical mechanism by chance? Perhaps. But it is worth bearing in mind that his theory was likely grounded in observation, and formulated to be as parsimonious as possible. I think that rather than chance, it is instead even clearer we are reading the work of someone with a scientific mind, curiosity about nature, and a belief in a profoundly ordered universe.

Joshua Harvey

Cate Watkinson – VideoLog2: Embodying Light

Cate Watkinson talks through her ideas for the National Glass Centre, University of Sunderland’s, upcoming exhibition on Grosseteste, light and colour, in the autumn. This is the second film made by Claire Todd, exploring aspects of how the pieces and the exhibition come together. Colour, Light and the magic of glass….

We are very grateful for the support of the Durham University Institute of Advanced Study in making these films possible.

New Ordered Universe Publication

The Ordered Universe project is pleased to announce its latest publication, for the Applied Optics journal, Vol. 56 (2017), G197-G204, and fully open access. The experiments and writing of the paper were led and marshalled by expertly  Joshua Harvey (Mellon Foundation funded graduate student at Oxford University, Dept of Engineering Science and Pembroke college), with assistance from other members of the team, from the sciences and humanities. The paper focuses on the middle part of Grosseteste’s treatise On the Rainbow (De iride) and the shape that the rainbow forms in the sky. This precedes discussion of the colours of the rainbow, covered in other Ordered Universe papers. The current paper offers an historical context for the treatise before moving to the main discussion, testing Grosseteste’s optical thought with physical experiment and physics-based simulation. The results are available below, and show, again, the benefits of collaborative working to unlock problems posed by thinkers of the past.

Screen Shot 2017-06-30 at 18.06.45

Colin Rennie – Video-Log1: Making a Rainbow

The first in a short series of films by Claire Todd chronicling the development of the National Glass Centre exhibition drawing on Ordered Universe research and the scientific works of Robert Grosseteste. Here Colin Rennie talks about his rainbow sculpture.


We are very grateful to Durham’s Institute of Advanced Study for providing resource to enable the making of these films.

Colour is Light: Through a Glass Darkly

Another memorable day at the National Glass Centre. Giles, Brian and Alex Carr, together with David Lowther (Leverhulme Early Career Fellow at Durham, working on the history of zoology in the modern period, especially of collections and birds), went over to Sunderland to see the preparations for the Grosseteste-inspired exhibition opening in October.  We also went to complete the filming for the documentary element of Through a Glass Darkly with Alan Fentiman. We had a fantastic time – Colin Rennie made one of his rainbow strands for us. As you’ll see from the clip below, this was quite extraordinary, culminating in molten glass being stretched and spun, changing colour as it cooled.


The final products of rainbow sculpture, some 20 or so, will be mounted in an steel frame, each strand moving seamlessly from one colour to another.


Cate Watkinson took us through her installations, with models of the larger pieces of glass in sequences. We experimented with torchlight and one of the circular moulds of blue glass, creating internal and external shadows, reflection and patterns at the edge of diaphanous media (as Grosseteste might have observed). Cate is working too on embedding Grosseteste’s treatise De colore (or parts of it) into glass, as well as the larger colour pieces and the movement from black to white.

The exhibition opens on 20th October – we’ll have more updates on progress and activities around the exhibition. For now, we can safely reveal that it will be amazing.


Exhibition at the National Glass Centre, University of Sunderland

Absolutely thrilled to announce an upcoming exhibition at the National Glass Centre, University of Sunderland. Artists Cate Watkinson and Colin Rennie, with contributions from MA and PhD students from the Centre will be creating a fantastic array of installations, all based on Grosseteste’s treatises on light, colour and the rainbow. The exhibition will run from October 2017 to February 2018 at the Glass Centre.

Amongst the pieces to be created are pillars of colour casting shadow and reflection, and an exploded rainbow, with sequences of colour moving and blending into each other:

Other pieces will work with medieval imagery and text; all will be exploring Grosseteste’s idea that Colour is Light ‘Color est lux’. Or, as he put in his Commentary on the Genesis Creation story, a constant mediation and mingling of the elements:

Nor should anyone think that the earth could not have been coloured at the beginning, given that colour is light in a diaphanous medium and light was not yet created. In fact, if the creation of things was successive the fire was mixed with this solid earth since the beginning, as it is now; and the incorporation of its light (that is: the fire-light) in the moisture of the earth made the earth coloured. In fact, these elements that we perceive around us are not pure, but mixed with each other, and are named from the element that predominates.
[Hexaemeron 4.7.2: ed. Richard C. Dales and Servus Gieben (Oxford, 1982); translated by C.F.J. Martin as On the Six Days of Creation (Oxford, 1996)]

Flowing from the Through A Glass Darkly collaboration the exhibition also forms part of the City of Sunderland’s bid for UK City of Culture. It really is amazing to see the continued inspiration that Grosseteste’s thinking moves and shapes, and to see different levels of analysis, interpretation and explanation of these texts through glass.

We’ll be creating a Vlog to track the progress of the making – many thanks to Claire Todd – and to whet your appetites for the exhibition, in its various modes: meditative and explosive by turns.

Medieval and Modern Science at Ely

On 11th February, Hannah and Giles were given a very warm welcome at Ely, at an open seminar organised by the Bishop of Huntingdon, Rt Revd David Thomson. David is also an Ordered Universe stalwart, taking the lead particularly on the Middle English version of some of Grosseteste’s earliest treatises. It was an especial pleasure, therefore, to be invited to Ely to present the project and its current work, some of the most recent scientific elements, and to participate in a lively and instructive question and answer session. We explored the life and times of Grosseteste, the context for his scientific works, and research into his rainbow treatise with Hannah’s ongoing work on retinal imaging.

We then ran a collaborative reading session on Grosseteste’s treatise On Colour. This was very stimulating, and, no matter how many times we read the text, new thoughts and and new interpretations arise. In this case the ideas were generated by the excellent and thoughtful participants. The event was run in the Old Palace, and our thanks go to all of the organisers, those who attended and to Bishop David. Certainly we came away with fresh insights. We then enjoyed a guided tour of the Cathedral, taken especially to see the Prior’s Door, with it’s magnificent carvings, including the zodiac. A stunning way to round off our visit to Ely. Thanks to all who made it possible!

Colour, Light, Glass and Exploding Rainbows

Our Through a Glass Darkly meeting last week gave a considerable amount of food for thought. Catching up with the progress that the Ordered Universe team have made on Grosseteste’s treatises over the last three symposia On the Liberal Arts, On the Generation of SoundsOn the Six DifferencesOn the Sphere and the very first glimpses of On Comets was a reminder, again, of the range, complexity and beauty of his thought. The themes of body and of movement, of the influence of bodies on one another and the interplay of authoritative models and the natural world around him, emerge in these discussions in a powerful and prominent manner. We can see more clearly the three stages through which Grosseteste’s thought moves, from an alchemical, elemental and astrological view of the universe, to one dominated by light and embodied light at that, to the influence of light rays. These modes are not discreet, but overlapping, and are not presented by Grosseteste as contradictory to each other. His condemnation of judicial astrology in the Hexaemeron, for example, is orthodox and Augustinian, astrology cannot take the place of free will and must not be imagined to come to to doing so. At the same time Grosseteste reveals a frustration with technological inadequacies that render accurate measurement of time and space too difficult to make predictive judgment from star-gazing possible. Continue reading