Herschel’s Grand Forty-Feet Telescope

Herschel's Telescope

Contributor: Elsa Cazeneuve

Location: National Maritime Museum, Greenwich, London

Description: This document is a hand-coloured illustration of Herschel’s Grand Forty-Feet Reflecting Telescope, engraved by J. Pass for the 1819 edition of the Encyclopedia Londinensis (or Universal Dictionary of Arts, Sciences, and Literature), and featured in the chapter related to “Optics”. At the time, Herschel’s Forty-Feet Telescope was the largest in the world and cost over 4000 pounds, paid for by King George III. Its construction began in 1786, and was completed in 1789; the telescope was erected at Herschel’s home, near Slough. It soon became a touristic attraction and a scientific curiosity: people would travel all the way from Paris to admire this new wonder and some even likened it to the Colossus of Rhodes. Later on, the telescope was marked on the 1830 Ordinance survey map of the area. Unfortunately, Herschel’s last telescope would take years to demonstrate its worth, as it had to rotate very slowly to show various aspects of the heavens. William Herschel and his sister Caroline, who worked together, found that the telescope was difficult to set up and maintain and William’s son eventually had it dismantled in 1840. Interestingly enough, the dates of construction and demise of the forty-footer cannot but recall those of the Romantic era: Herschel’s grand telescope came to serve as a symbol of the unbounded Romantic imagination.

Nevertheless, Herschel’s telescope also remains a staple of scientific progress: it was adopted as the official seal of the Royal Astronomical Society, and testifies to the ambitions of Herschel to plunge ever deeper into the sky and understand the language of the heavens. Indeed, Herschel made more than 400 telescopes during his life, and his fame and skill enabled him to establish a successful business. He worked on new designs to overcome the limitations of the technology of the period, and was the first astronomer to catalog more than 2400 nebulae, which in the 20th century would come to be recognized as galaxies beyond our own. Herschel was perhaps best known for his discovery of a new planet, Uranus, first observed on the 13th of March 1781. His accidental discovery of infrared light from the sun – which would lead to our understanding of the electromagnetic spectrum – was also to become a landmark of optics science, which in turn came to influence Romantic poets such as William Wordsworth and Samuel Taylor Coleridge.

Seeing is in some respects an art, which must be learnt”, writes Herschel to William Watson on the 7th of January 1782. Watson, secretary to the Royal Society of London, first met Herschel in 1781 and was very much impressed by his self-taught knowledge of astronomy and his hand-made telescopes. He therefore introduced the astronomer to the Royal Society of London. At the age of 43, William Herschel met George III at Windsor and became the King’s Personal Astronomer. Between 1782 and 1802, Herschel had over a hundred papers published by the Royal Society (focusing on the volcanos on the surface of the moon, the problem of double stars, the nebulae…). Many of these papers came to be studied by William Wordsworth and Samuel Taylor Coleridge, who both practiced astronomy as part of their daily activities in Nether Stowey. This collaborative star-gazing inspired some of their most famous poems: the narrator of Wordsworth’s poem “The Thorn” carries his telescope up the mountain; the crowd gathers around “A Telescope upon its frame, and pointed to the sky” in “Star-Gazers”; Coleridge’s Mariner uses his spy-glass to observe the moon and the stars high above the ocean. Both poets were also influenced by Erasmus Darwin’s poem The Botanic Garden (1791), the first canto of which celebrates the discovery of Uranus.

So, late descried by Herschel’s piercing sight,
Hang the bright squadrons of the twinkling night
Flowers of the sky ! Ye to age must yield,
Frail as your silver sisters of the field ! (ll.371-381)

Among the sources of inspiration of “The Thorn” was also a huge double-page illustration of Herschel’s forty-feet telescope, together with a lengthy description of its magnifying capacity. The narrator of the poem, an amateur astronomer climbing up a mountain, mirrors Wordsworth and Coleridge’s activities, as evidenced in the sixteenth stanza:

For one day with my telescope,
To view the ocean wide and bright,
When to this country first I came,
Ere I had heard of Martha’s name,
I climbed the mountain’s height:
A storm came on, and I could see
No object higher than my knee. (ll.170-176)

Ironically enough, the telescope becomes a metaphor for the narrator’s figurative blindness, as he overlooks the suffering of the young woman next to him. Because he is obsessed with his need to scrutinize the heavens, the narrator seems to observe life and his surroundings only distantly. In that respect, the telescope stands as a metapoetic device: it is turned back upon the self, and invites us to look inward as much as upward. The magnifying power of the telescope, which converts distant lights into planets and stars, is associated with that of imagination as defined by Wordsworth, in his Note to “The Thorn”: “imagination, by which word I mean the faculty which produces impressive effects out of simple elements”.

Likewise, Samuel Taylor Coleridge used the telescope as a metaphor for a renewed understanding of human faculties. In his Lectures, Coleridge conceived of an analogy in which Faith came to be associated with a telescope, allowing us to further the powers of Reason: “Now what the telescope is to the eye, (…) faith, that is the energies of our moral feelings, are to the reason. Reason is the eye, and faith (all the moral anticipation) the telescope”(1). “By the eye of Reason through the telescope of Faith, i.e. Revelation, we may see what without this telescope we could never have known to exist”(2) .

For Coleridge, the telescope symbolizes an enhanced visual perception, which will allow mankind to see through the illusionary fragmentation of the world. This “armed vision” epitomizes a new way of seeing, one that sets the poet free from “the despotism of the eye”(3) , enabling him to look both upward and inward. The very word “telescope”, which comes from the Greek tele skopos (meaning ‘far-seeing’) encapsulates in its etymology the prospects of a device related to teleos, meaning “end, goal”. Herschel’s telescope therefore paved the way for a Romantic redefinition of sight, which strove to reach both inner depths and new heights.

Creator: J. Pass

Date: 1819

Image Rights: National Maritime Museum, Greenwich, London

Object Type: Hand-coloured illustration

Format: Sheet 293 x 222 mm

Language: English


  1. S.T. Coleridge, Lecture 9, 22 Feb 1819, LHP, I, p. 377.
  2. T. Coleridge, ‘Aphorism XXII’, Aphorisms on Spiritual Religion B, in AR, p. 341.
  3. S.T. Coleridge, Biographia Literaria, Chapter VI.
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