Special Collections Visiting Scholars – Visiting Forbes’ coloured atmospheres
James David Forbes (1809–1868) was part of an early generation of natural philosophers interested in quantifying climate and weather in order to determine how the Earth’s atmosphere behaves. Before the nineteenth century, meteorology focused on atmospheric anomalies, mostly optical in nature, such as meteors, lunar rainbows, lightening and curious lighting effects. Considered as localized events, reports relied on qualitative observations based on eye-witness accounts or physical effects of severe weather. Daily atmospheric conditions were not part of a meteorologist’s study until the 1780s when ‘weather’ began to be considered in terms of causes and daily patterns. The Forbes manuscripts held in Special Collections at St Andrews University form an extensive and rich collection of scientific notebooks, travel diaries, correspondence and personal reflections among which this ‘new meteorology’ features largely. Like many late eighteenth- and nineteenth-century scientific figures, Forbes conducted research on a wide range of subjects and applied knowledge in surprising and usual ways. My research objective in using the archive was to examine Forbes’ studies of meteorology, colour and aesthetics, and I was delighted at the material I found.
Forbes is a key figure for my research because of his intense interest in physics. He wanted to apply physics to everything, including geology, the history of which I specialized in for my PhD dissertation. During the early nineteenth century in Britain, students of earth science can be divided generally into two sorts: individuals who claimed that fossils could be used to correlate strata (so in essence they used a history of biology to establish an earth history), and individuals motivated by a mineralogical understanding of how earth behaves under physical circumstances such as heat, pressure, as well as chemical changes. I’m primarily interested in the second group and was delighted to find Forbes such an excellent fit. In a letter to geologist and antiquarian Samuel Hibbert, Forbes criticises ‘descriptive geology’ that emphasizes plant and animal fossils and leads to speculation on the figure and revolution of the Earth. By contrast,
‘analytic geology, consists of causes … & requires more aid from the natural philosophy than nat. hist. The phenomena of volcanoes for instance are real objects of analysis & require the aid of chemistry, of pneumatics, hydrostatics & I know not how many of the [?] physical sciences. The mere niceties of superposition & slips & dislocations are of far less important in a grand & general point of view.’
(msdep7 – Letterbook I, p281)
Forbes’ early meteorological journal presents a wonderful history of instrumentation. He describes a barometer he made and includes all the literature consulted for its construction. A later entry details improvements Forbes made to the instrument. John Herschel (1792–1871) was a prominent figure in re-shaping traditional modes of visualizing weather and actively encouraged Forbes to pursue meteorology and his research on heat and solar radiation. Sources of heat, whether it originated from the Sun or from the Earth itself, and its effect on the atmosphere occupied Forbes for much of his scientific life.
Solar radiation, the reflection and absorption of light by objects, and the behaviour of the atmosphere all come together in Forbes’ work on vapour, colour and optics. His interest in optical meteorology is based on Newtonian systems of prismatic colour that focuses on a colour spectrum produced from a flint-glass prism. Focusing on the physical nature colour, Forbes attempted a system of colour mixing for pigments based largely on the work of the Swiss-German mathematician and natural philosopher Johann Lambert. Lambert published two works on light measurement, Photometria and Cosmologische Briefe, which also included a discussion on effect of light on the appearance of coloured materials. In 1772, he published an extended account of colour in his Description of a Colour Pyramid Painted in Calau’s Wax, a copy of which Forbes held in his personal library – the library is now also held at the University of St Andrews. Lambert’s fascinating treatise mediates tensions between prismatic colour and material colour systems that artists and artisans had long recognized as incommensurable, and effectively describes how coloured pigments behave according to atmospheric and object density.
I am very much looking forward to continuing this research on the histories of meteorology, colour and aesthetics. Forbes’s strong and (sometimes) controversial opinions make him an engaging figure of study, and while scholarship has largely eclipsed him in favour of his scientific peers, Forbes’ mss contain a wealth of information. I am delighted to have been given the opportunity to explore this very special collection.
Special Collections Visiting Scholar 2015 & Affiliated Scholar at the Department of History and Philosophy of Science in the University of Cambridge