Jeremiah Horrocks, astronomer and poet

Abstract

This paper will consider the work of Jeremiah Horrocks, the first astronomer to observe the transit of Venus, with reference to his book on the subject (Venus in sole visa). It also explores a New Zealand connection. The paper focuses on Horrocks's interest in writing poetry, the relationship between his poetry and his astronomical work, and what this can tell us about the development of scientific writing in the seventeenth century.

Keywords:

• transit of Venus
• Jeremiah Horrocks
• astronomy
• scientific writing (history)
• science and literature

The first person to observe the transit of Venus was Jeremiah Horrocks, who was living in Lancashire in 1639. Only 20 years of age, he was both an innovative astronomer and a poet. To consider why Horrocks wrote poems as part of his report and how they were related to his astronomy can cast light on the evolution of scientific writing.

Figure 1  Jeremiah Horrocks observing the 1639 transit of Venus, as imagined by painter JW Lavender in 1903.

Although he died in 1641, Horrocks had already done so much ground-breaking work that he was later described by Sir John Herschel as ‘the pride and boast of British astronomy’ (Aughton 2005:210), by Sir Isaac Newton as ‘the excellent astronomer’ (ibid.:198), and by WF Bushell as ‘The Keats of English Astronomy’ (Bushell 1959). The Royal Society, established in 1660, was deeply impressed by the fact that ‘many years before its [the Society's] foundation there had been in England a man who had fully appreciated their aims and raison d’être’ (Aughton 2005:8). One of the Society's first projects was to collect and publish a posthumous collection of Horrocks’ writings (Wallis 1672–73). His analysis of transit data represented a milestone in astronomy because it led to a better understanding of the nature and size of the solar system. Together with Horrocks’ work on other topics such as the elliptical nature of the moon's orbit, it provided a compelling model of how astronomy could advance by combining precise observation with theoretical extrapolation.

Because this scientist's life is highly relevant to the emphasis on young people that will form an important aspect of the ‘transit of Venus’ celebrations in New Zealand, I am going to start anecdotally by describing my own encounter with his story as a 15-year-old. In the 1950s my most prized possession was a 3½” reflecting telescope—it seemed small, but with 60× magnification it was actually a lot more powerful than Jeremiah's—and at first I planned to make astronomy my future career. I was fascinated to learn that a lunar crater in the vicinity of Hipparchus carried my surname. Of course, that name commemorated the first observer of the transit of Venus, and once I had done some reading about Jeremiah and the discoveries he had made as a teenager, he became a major role model for me. I was also excited to discover that there was an assumption (or myth) in my family that he was a relative, since my grandparents before their emigration to New Zealand in 1925 had lived in the same region of England.

Though I ended up making an academic career in the humanities, the arts have always seemed to me closely related to science in their awareness of the big picture. Practitioners in both fields admire work that is original and well formed, as illustrated by Paul Dirac's comments about the ‘beauty’ of a powerful equation or theory (Farmelo 2009:301, 435). Both fields require some creative, lateral thinking, and both undertake gruelling, ambitious projects in which care must be devoted to every detail.

The evolution of scientific prose

One of the aspects of Jeremiah Horrocks's book Venus in sole visa (‘Venus seen on the sun’) that fascinated me was the wide range of its style, from precise scientific description to lyrical poetry. It is appropriate to call him ‘the Keats of English astronomy’ not only because he did so much great work before his early death but also because he was an accomplished poet who expressed some of his ideas about astronomy in poetic form.

Horrocks and his contemporaries still spoke of ‘natural philosophy’ rather than ‘science’. Scientific writing in the impersonal, specialised forms that we know today was still at an early stage of development, and even within the Royal Society ‘significant methodological differences existed’ (Hunter 1989:208). Persuasion is part of any scientific argument, and at university Horrocks and his peers were taught the techniques of rhetoric as tools of persuasion. Those who championed empirical investigation as an alternative to Aristotelianism still made use of these literary methods. For example, Francis Bacon, a strong influence on Horrocks (Aughton 2005:46), expressed some of his ideas through aphorisms, fictional dialogues, and utopian fantasy.

Horrocks was quick to grasp the power of mathematics and exact observation. But there are also pages of Venus in sole visa where the author wanted to express his excitement about some aspect of nature, make fun of the mistakes of careless scientists, engage in philosophical speculation, relate his findings to religion, or be playful and amusing as a break from pages of calculation. Modern scientific journals would find it hard to take such a writer seriously or would assume that this was a piece of popular science, the secondary genre to which those activities are now relegated.

It is important to realise, however, that much history lay behind Horrocks's practices. Poetry developed earlier than prose, and Greek and Roman writers often used it for philosophical works, such as Lucretius’ De Rerum Natura. Patricia Fara points out that those writing seriously about nature in the sixteenth century attached importance to ‘emblems, symbolic pictures embellished with mottos, and explanatory verses’ (Fara 2010:119–120). Richard Holmes, in his book on the interaction between science and literature in the late eighteenth and early nineteenth centuries, quotes poems by Erasmus Darwin, Humphry Davy and Sir John Herschel among others (Holmes 2009).

Today we assume it is necessary for science to have shed poetic or figurative aspects, but metaphors remain embedded in all forms of verbal language (Lakoff & Johnson, 1980). Furthermore, there is much to be said for the colour and vitality of so-called ‘popular science writing’, at least the best of it. Some of the greatest modern scientists have contributed to this genre. Many share an interest in music or art; some have managed to add a playful touch to scientific papers (Baker 2010:85); and poems have been known to turn up from time to time on lab noticeboards (Farmelo 2009:171). The book which won the 2009 Royal Society of New Zealand Book Prize (Priestley 2009) includes poems on scientific themes.

A eulogy to the telescope

As a serious contribution to astronomy, Venus in sole visa was written in Latin since this was the language normally used in the seventeenth century by educated writers throughout Europe, though scientific discoveries were now putting strains on its vocabulary. The classics of Latin literature were still an important part of education, and they provided Horrocks with the basic (dactylic hexameter) form of his own poems.

A survey of the poetry in Venus in sole visa will help to clarify what Horrocks was doing with the genre, and at the same time highlight what was innovative about his approach to astronomy. I will use AB Whatton's 1859 English translation. Although Whatton changes the Latin metre into iambic pentameter, and at times his translation is too free, he does convey the basic spirit of the original.

The first of the four poems in the book is an ‘Encomium telescopii’, a eulogy to the invention of the telescope and the marvels it has revealed (Hevelius 1662:114–115; Whatton 1859:119–121). Having examined existing Ephemerides (astronomical tables), Horrocks had found them lacking in precision, so the immediate task was to ‘fix/Each orb in its own ordered place’. Horrocks's poem champions scientific methods of precise observation. In contrast, some other scientists of the time were yet to make a clean break with astrology, alchemy and other esoteric traditions (Hunter 1989:54–55).

Figure 2  The title page of Jeremiah Horrocks's book, as it was first published in 1662, edited by the astronomer Johannes Hevelius.

The poem allows Horrocks to express his deep admiration for ‘bold Copernicus’, whose discoveries will ‘soon surpass the utmost bounds of ancient lore’. It emphasises the way the telescope gives material reality to the bodies of the solar system—it reveals ‘spots upon the sun’, ‘rocks and ocean-depths’ (the plains we call maria on the moon), and ‘penetrates the veil’ that has obscured Mercury and Venus. It confirms that the planets shine by ‘borrowed light’ and ‘revolve’ around the sun. These are all departures from the traditional Ptolemaic view of the heavens.

The poem conveys Horrocks's excitement as a young man using new technology to extend human sight:

Where'er the seal of youth shall scan the heavens,

O may they cherish thee above the blind

Conceits of men, and the wild sea of error,

Learning the marvels of this mighty Tube!

Horrocks had a deep interest in equipment that could help him to determine time, size, and position with increased accuracy. His father is thought to have been a watch-maker, and his wife's brother Edward Aspinall was an innovator in the field (Bushell 1959:15). Astronomy had close links with the development of navigation, and Horrocks's study of the moon's orbit would assist in the calculation of longitude. Such developments helped to prepare for voyages of exploration such as those of James Cook, who made navigational use of the ‘lunar distance method’ when he sailed to Tahiti to observe the 1769 transit of Venus.

Figure 3  Horrocks's diagram of the transit of Venus (from his book).

Horrocks's second poem, addressed to the planet Venus, is a playful attack on countries such as North America that were well placed to observe the transit but did not yet understand the importance of astronomy (Hevelius 1662:118–119; Whatton 1859:135). Horrocks knew that the triangulation of observations from different parts of the world could refine the calculation of planetary distances. His poem ends by imagining the next transit of Venus:

 Thy return

Posterity shall witness; years must roll

Away, but then at length the splendid sight

Again shall greet our distant children's eyes.

A new world view

The third poem vividly contrasts the Ptolemaic with the Copernican system (Hevelius 1662:129–130; Whatton 1859:164–167). Horrocks grew to maturity in the midst of a great shift in epistemology and the understanding of nature, and he was quick to develop a clear understanding of its implications.

Ptolemy's conception of the solar system formed part of a larger world view that mixed physics with metaphysics. It assumed that God was not separate from the world and that He favoured equal distances and symmetrical forms such as spheres, circles and epicycles. The universe had a hierarchical organisation, with Earth at the centre and God (as Prime Mover) occupying the outermost sphere. The work of Copernicus, Galileo and Kepler helped to replace this ‘top down’ system by an experimental, observation-based model. This assumed that God created the world but then withdrew, leaving it to function by its own laws. The world became a material realm, free of the angels, ghosts and other spirits that had existed within the medieval model. The planets, including the Earth, revolved around the sun and their orbits were ellipses rather than perfect circles.

There were fierce clashes between the new model and the Christian establishment. Horrocks, whose religious views seem to have leaned towards Puritanism, had no difficulty in reconciling the new scientific model with Christian belief (Aughton 2005:28). Indeed he presented the Ptolemaic system in this poem as a less worthy conception of God, more relevant to the Classical world and its pagan gods. In this iconoclastic poem, Ptolemy's ‘narrow-bounded world’ and ‘poor machine’ is replaced by a large, complex, physical universe, accessible to everyone through careful observation:

The clouds which once obscured our mental sight

Are gone for ever; great Copernicus

… lays open to our view

The arduous secrets of wide heaven's domain.

Turn hither then your grateful steps, for here

Are wondrous mysteries that you may learn,

Open to all whom …

The love of truth impels …!

The final poem is a eulogy for Johannes Kepler, who had died in 1630 (Hevelius 1662:133–134; Whatton 1859:177–179). Horrocks praises him for having demolished the ‘fictitious circles’ by proving that the orbits of the planets were elliptical. He sees the precision of Kepler's analysis as exemplary:

[With] faithful hand [thy mind] traced the motions which …

Nature hath decreed. While yet the power

Was thine to guide their way, true to thy rules

Each planet in its ordered path revolved,

And all rejoiced to follow in thy train.

Poetic licence allows Horrocks to indulge occasionally in anthropomorphism (the planets ‘rejoiced’). We are never confused by such playful details because of the scientific observations that form the basis of the book. Also, he makes fun of the personification practised by astrology:

 The modern seers

Portend that heaven's disturbed by monsters which

Are unintelligible to mankind… .

Horrocks was generous in his praise of the individuals he regarded as genuine astronomers, but he understood that even their work needed to be questioned and refined. The fact that he devoted a number of pages of his book to pointing out errors made by Kepler did not diminish his deep respect (Applebaum 2004). In fact, the influence of his posthumous publications played an important role in reviving interest in Kepler in Britain. As HC Plummer remarks, the support which Horrocks gave to his predecessor ‘was exactly that which the astronomy of the age demanded. Kepler had placed the science in the firm position from which the next advance was to come’ (Plummer 1940–41:47).

Besides praising exemplars, Horrocks also poured scorn in his poems on bad scientists, naming those who tried to claim credit for the work of others (‘bold thefts’) or who were lazy and cut corners (‘the slothful retinue’). In those early days scientific writing could reach ‘extraordinary levels of bitterness and vituperation’ (Serjeantson 2008:171–173).

The legacy of an astronomer

In admiring these four poems by Horrocks, I am not trying to argue that they are important examples of poetry (in either their Latin or English version), but I enjoy their energy as examples of writing in a period when it was still permissible for a scientist to express his excitement, his sense of play, and his interest in philosophical and religious implications, elements that are today seldom articulated publicly until the biography or autobiography of a scientist is published.

Venus in sola visa contains a great deal more than the poems—not only a detailed record of Horrocks's observation of the transit but a brilliant analysis which yielded new information about sizes and distances.

After four centuries, Jeremiah remains a powerful role model as someone who educated himself in the rigours of scientific method, and who used that method (at the early age of 20) to make a major contribution to astronomy. In June 2012, we should remember him as the first observer of the transit of Venus. And his excited comments on that occasion are still memorable:

Contemplate, I repeat, this most extraordinary phenomenon, never in our time to be seen again! the planet Venus drawn from her seclusion, modestly delineating on the sun, without disguise, her real magnitude. (Hevelius 1662:112; Whatton 1859:116–117)

Acknowledgement

My thanks to Dr Bill Barnes of the Department of Classics and Ancient History at the University of Auckland for analysing some sample passages of Whatton's translation.