John Franklin and John Herschel’s Telescope

When deciding whether I had anything to contribute to World Space Week, I realised with a bit of dismay, that I had missed an opportunity whilst on a recent holiday in Bath, to have visited the home of brother and sister, William, and Caroline Herschel. The pair had been famous for their endeavours in astronomy during the late eighteenth and early nineteenth centuries. William was famous for discovering Uranus in 1781, with Caroline being his dedicated assistant, who recorded and catalogued his discoveries, right up until his death in 1822. Caroline had also been the first woman to discover a comet, which quickly multiplied into a total of eight comets in total. Perhaps that visit to their house in Bath, where their interest in astronomy began, can be saved for another year.

Instead, I decided to see whether we had anything Herschel related in our online catalogue and was quite surprised to discover a couple of letters by Sir John Franklin, the famous explorer, mentioning William’s son, John. After doing a little bit of research into John Herschel, and why Franklin may have mentioned him in his letters, I was even more surprised to find that there may be more of a connection than the very brief mention made in the letters. The first reference made was in a letter Franklin wrote to his friend, John Richardson, whilst on military duties in Greece dated 30 Dec 1831. In it he makes mention of the possibility of John Herschel’s knighthood and missing out in the election to the role of Chair for the Royal Society.

Sir John Frederick William Herschel. Mezzotint by W. Ward, 1835, after H. W. Pickersgill, Wellcome Trust Collection, Public Domain

The second letter I came across was written by Franklin to his sister, Hannah Booth, who lived in Ingoldmells in Lincolnshire, dated 28 Nov 1836. In it, John updates her on his travels to Tasmania, to take up the Governorship there, which included a stop off in Cape Town in South Africa. At the time of writing the letter, Franklin states he had already been in the area for two weeks. He makes a particular reference to some of the astronomical observations he has made:

We were favoured last night with a view of the Magellanic Clouds through Sir John Herschel’s large telescope and truly magnificent was the sight- clouds came on & prevented our seeing Orion through it or the Southern Cross which we were to have seen.

D8760/F/FBO/1/1/10, Letter from Sir John Franklin to his sister Hannah Booth, on stop at Cape Town on the journey to Tasmania, 28 Nov 1836

It is obvious that Franklin admits to using John Herschel’s telescope to admire the stars. By saying he used the ‘large telescope’, it is quite probable that he meant the twenty-foot telescope that Herschel had taken set up near his home. Herschel spent four years, between 1834 and 1838, in Cape Town, with his family and a house full of servants, so he could do similar observations to those his father had done on northern skies for the south. He used the same type of giant telescope but reduced the size of it compared to his father’s forty-foot one he had constructed at their home in Datchet, near Windsor. The family had moved there from Bath after William Herschel had been made Royal Astronomer by George III in 1782, which also made it easier to use such a giant telescope.

Both William and John’s telescopes worked in a similar way. They both worked on the principle of reflection, which involved placing mirrors at either end of the tube that would form the telescope. At the ground end, there would be a larger curved mirror, with a smaller mirror being placed at the end pointing towards the sky. The bigger the mirrors used, the more light it would reflect, thus it could look deeper into space. The whole telescope was then placed onto a large frame, that was worked by ropes and pulleys. There was also a viewing platform attached to the frame. The image below, whilst it shows William Herschel’s forty-foot example, shows how both telescopes would have looked.

Astronomy: a 40-foot telescope constructed by William Herschel, in use outdoors. Coloured etching, 18–.Wellcome Collection.Public Domain Mark

If it is the case that Franklin visited Herschel to use the telescope, it certainly would have been an extraordinary meeting. Franklin himself was indeed keen on astronomy, as can be seen in the way he writes with such enthusiasm in the small passage he uses to mention his own observations. It would have certainly been a meeting of two great men of the age. Herschel certainly had pedigree as he had already made a name for himself through his talents in all manner of scientific and mathematic activities. Franklin would also have needed knowledge in astronomy during his many voyages to help navigate. The possibilities of such a possible meeting are indeed tantalising.

Sadly, I have little or no further information on this, so I have written this post in order to put the theory out there. If anyone has any further ideas on this, than please let us know. For the moment, I hope this has served as an interesting little snippet. If you would like to know any more about the Herschels and their amazing discoveries, I would suggest further researching them, as there appears to be a lot of information out there. A good place to start may include some of the items listed in the below bibliography.

Bibliography:

Brian Warner, Cape Landscapes: Sir John Herschel’s Sketches, 1834-1838 (Cape Town: University of Cape Town Press, 2006)

Gunther Buttman, The Shadow of the Telescope: A Biography of John Herschel, translated by B. E. J. Pagel (Guildford & London: Lutterworth Press, 1974)

Rachel Knowles, What Regency Women Did for Us (Barnsley: Pen & Sword, 2017)

D8760/F/FBO/1/1/10, Letter from Sir John Franklin to his sister Hannah Booth, on stop at Cape Town on the journey to Tasmania, 28 Nov 1836

D8760/F/FJR/1/1/61, Letter from John Franklin to his friend John Richardson, while serving on military duty in Greece, 30 Dec 1831