In addition to the many historical and literary works in his library, Guilford also acquired a small number of scientific manuscripts, including this collection of mathematical, scientific and alchemical works by the philosopher and scientist Roger Bacon (1214-1294). This manuscript dates from the third quarter of the 14th century and the text shown here, on the properties of light, is from the second part of Bacon's Tractatus de Multiplicatione Specierum, which illustrates his innovative application of geometry to optics.
The British Library, Additional MS 8786, ff. 34v-35. Copyright © The British Library Board