Declining an offer from the
Duke of Sussex that they travel to
South Africa on a Navy ship, Herschel and his wife paid ₤500 for passage on the 'S.S. Mountstuart Elphinstone', a ship of 611 tons, which departed from Portsmouth on 13 November 1833.
The voyage to South Africa was made in order to catalogue the stars, nebulae, and other objects of the southern skies. This was to be a completion as well as extension of the survey of the northern heavens undertaken initially by his father
William Herschel. He arrived in
Cape Town on
15 January 1834 and set up a private 21ft telescope at
Feldhausen at
Wynberg. Amongst his other observations during this time was that of the return of
Comet Halley.
However, in addition to his astronomical work, this voyage to a far corner of the British empire also gave Herschel an escape from the pressures under which he found himself in London, where he was one of the most sought-after of all British men of science. While in southern Africa, he engaged in a broad variety of scientific pursuits free from a sense of strong obligations to a larger scientific community. It was, he later recalled, probably the happiest time in his life. In an extraordinary departure from astronomy, he combined his talents with those of his wife, Margaret, and between 1834 and 1838 they produced 131 botanical illustrations of fine quality, showing the Cape flora. John Herschel used a
camera lucida to obtain accurate outlines of the specimens and left the details to his wife. Even though their portfolio had been intended as a personal record, and despite the lack of floral dissections in the paintings, their accurate rendition makes them more valuable than contemporary collections. As their home during their stay in the Cape, they had selected 'Feldhausen', an old estate on the south-east side of Table Mountain. Here he set up his reflector to begin his survey of the southern skies.
Intrigued by the ideas of gradual formation of landscapes set out in
Charles Lyell's Principles of Geology, he wrote to Lyell commenting and urging a search for natural laws underlying the "mystery of mysteries" of how species formed, prefacing his words with the couplet:
:
He that on such quest would go must know not fear or failing
:
To coward soul or faithless heart the search were unavailing.
Taking a gradualist view of development, he commented
:"Time! Time! Time! — we must not impugn the Scripture Chronology, but we
must interpret it in accordance with
whatever shall appear on fair enquiry to be the
truth for there cannot be two truths. And really there is scope enough: for the lives of the Patriarchs may as reasonably be extended to 5000 or 50000 years apiece as the days of Creation to as many thousand millions of years."
The document was circulated, and
Charles Babbage incorporated extracts in his ninth and unofficial
Bridgewater Treatise, which postulated laws set up by a divine programmer. When
HMS Beagle called at
Cape Town, Captain
Robert FitzRoy and the young naturalist
Charles Darwin visited Herschel on
3 June 1836. Later on, Darwin would be influenced by Herschel's writings in developing his theory advanced in
The Origin of Species. In the opening lines of that work, Darwin writes that his intent is "to throw some light on the origin of species — that mystery of mysteries, as it has been called by one of our greatest philosophers", referring to Herschel.
Herschel returned to England in
1838, was created a
baronet and published
Results of Astronomical Observations made at the Cape of Good Hope in
1847. In this publication he proposed the names still used today for the seven then-known satellites of
Saturn: Mimas, Enceladus, Tethys, Dione, Rhea, Titan, and
Iapetus.
In the same year, Herschel received his second Copley Medal from the Royal Society for this work. A few years later, in
1852, he proposed the names still used today for the four then-known satellites of
Uranus: Ariel, Umbriel, Titania, and
Oberon.
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