…there when the wave has gone by.
Common knowledge: John Conduitt recorded a memo on the last day of August in 1726 that mentioned a common glass prism purchased from Stourbridge Fair (a short walk along the Cam from Trinity to a broad green summer meadow in 1665, presumably worn to tan earth from the passage of crowds). We can easily link this to the tremulous prism and eye on fol.122r of the Questiones quaedam Philosophiae, and proceed from there. Now, we also know that Robert Boyle used a glass prism less systematically in his Experiments and Considerations touching Colour, and that Isaac Vossius mentioned prisms in his De lucis natura et proprietate (Amsterdam, 1662) beginning on page 67. So did Jean-Baptiste du Hamel in his Astronomia Physica (Paris, 1650), p.55: Non enim ut dictum est, commodius alibi quam in Iride seriem colorem intueri licet, in qua lux sincera, puros itidem colores efficit; cumque in Iride, quae per trigonum crystallinum efformatur, flavus color supremum teneat locum, cui rubens succedit, ac caeruleus tandem infimo loco subsidit; manifestum est rubeum colorem essa flavo debiliorem, ac minus lucis obtinere: quemadmodum rubeus est caeruleo vegetior. And before this? The image from Descartes above (Leiden, 1637). We shall not imagine the arc of ideas that led from Hugo Sempilius, and his citations of Witelo, Giambattista della Porta, and the Jesuit Claudius Richardus, to the first publications on broken sunlight in 1672.
Instead, we will walk across ice and gray asphalt on cloudy winter days, while wind blown oak leaves gather in the vestibules of life, and cubic salt bleaches the hallways we will enter later, under the icy pallor of white fluorescent tubes. At five the clouds will darken, and the Brooklyn Bridge will stretch across the misty East River from the cold windows of the crowded Q, and the distant waters of the harbor will be dark. Home to silence and four identical burners on the stove, pyramidal bags of Earl Grey tea, a Le Creuset kettle, and the sudden impossible blue sunflower of fire reminds us that color once existed in the world, and these lines of woodcut ink were once linked to visible spectra, miniature rainbows that range from 390-700nm/430-790 THz, symbols of a broken covenant in a January world now flooded with gray.