Posted by KeighleyAstro on Dec 1, 2021 in Main |

The guest speaker at the November meeting of Keighley Astronomical society was Mr Derek Barker from Bradford University of the 3rd Age. His talk was titled

Leviathan The telescope that Shipley and Heaton bought

(The 3rd Earl of Rosse and the Great telescope at Birr)

Mr barker commenced his presentation with a short history of the field family of Heaton.

The Field family of Heaton, Bradford.

Lords of the Manor of Heaton since early 17th Century.
Enclosures in Heaton (1780-81) & Shipley (1815) greatly increased their land wealth.
They owned coal, stone quarries, woods, cottages, farms and farmland, with easy access to the Leeds-Liverpool canal (John & Joshua Field).
In the next generation John Wilmer Field acquired the Lordship of the Manor of Shipley, by purchase, in 1829.

The daughters of John Wilmer Field and Ann Field, were Delia Field, and Mary Wilmer Field. In 1836 Ann Field married Arthur Duncombe, who was later to become Admiral Duncombe. He held big estates in East Yorkshire at Duncombe Park. Mary Wilmer Field (Born 1812 – died 1885) She marries Lord Oxmantown in 1836. She inherits the Heaton and Shipley estates, which by law become the propert of he husband.

The girls’ mother died shortly after Delia’s birth in 1813.
John Wilmer Field remarried, without further children.
Mary and Delia had happy childhoods, largely in Heaton, and stayed close to each other. Mary was described as serious, clever, and rich – rather than beautiful.

The Rosses 1

William Parsons, Lord Oxmantown was the eldest son of an Irish peer, Laurence 2nd Earl of Rosse.
The first names Laurence & William alternate in the family, and the family surname was Parsons.
After William’s marriage his parents moved to Brighton.
Within 5 years of his marriage his father (as well as his father in law) had died.

The Rosses 2

William succeeded to the title in 1841 becoming the 3rd Earl of Rosse, with large estates in Ireland, and he lived at Birr Castle, ‘Parsonstown’, Kings County (Now called county Offley).

Mary Field transformed the Rosse finances with the huge sums she brought as a marriage settlement and various legacies. The Heaton & Shipley rents, in modern money, have been estimated as £4.25M per year. Land sales occurred after William’s death.

The Rosses mostly held on to their Heaton & Shipley estates until the sale of most of their English property in 1911.

Life at Parsonstown (Birr), Eire

Both William and his father had seemed relatively liberal by the standards of the time, supporting:
Catholic emancipation
Parliamentary Reform Bill
But they would have opposed any property rights reforms
William had been educated Oxford and TCD.
He, like his father, was elected MP representing ‘Kings County’ but resigned before his marriage, in 1834.
Mary and William spent their married life renovating the castle: they had 11 children, of whom only 4 grew to adult life. The children were educated at home.

The Background to Leviathan

William was very interested in mathematics, engineering, chemistry, and……telescopes.
Elected FRS 1831, PRS 1848, and a member of RAS.
He knew that the largest telescope in the world had been built by near Slough by Sir William Herschel, who discovered Uranus, and realised that Polaris was a double star; Herschel had died in 1822.

His was a 49” (40 feet) reflecting telescope, not a refractor, but it was not considered a huge success.
It is difficult to produce large lenses without the various types of optical aberration, or to oppose the deformation by gravity of large masses of edge supported glass.

Herschel kept his techniques for casting and polishing large mirrors secret.

The Earl of Rosse, on the other hand, always provided accounts of his techniques to all who asked.
Grinding and polishing the metal mirror to the correct optical shape was the crucial technology.
Two discs simply rubbed round on each other, one concave and one convex.
The Earl of Rosse subsequently automated the process with a steam powered engine.

The development of Leviathan

The 3rd Earl developed all the construction techniques himself including a forge, and steam powered polisher
Classic bronze is a 10: 1 copper tin alloy.

He used a copper tin alloy (4: 1) for the speculum metal.
Why metal and not glass? Modern large reflectors use silvered glass.

Leviathan was just too early for this technique to have been adopted (silvering was developed 1856-57).
Getting perfect castings proved to be very difficult but by 1839 a 36” diameter mirror was cast and mounted.

It is possible that William created two mirrors of this size, one of which was unsatisfactory for some reason, but seemingly neither survive.

William was supported by his wife Mary, but wisely he also consulted experts:
Dr Thomas Romney Robinson (Armagh)
Sir James Smith who had worked with Herschel
Once the final 36” reflector was mounted, and in operation, he wanted something bigger.
His aim was to produce the largest telescope in the world.
He decided to construct a 72” diameter reflector, larger to collect more light.

He needed three crucibles to melt the required metal.
The first 4 ton mirror ‘broke’ during polishing.
The final 12 ton telescope was ready by 1845, with a reserve mirror prepared for use during cleaning the first.
The mounting was a huge problem.
The telescope was slung between two 50 feet high walls and the base of the telescope was sunk into a deep pit.

The iron telescope tube was so huge that a man could walk through it ‘wearing a top hat’.

The telescope was extremely cumbersome to manoeuvre, and was a transit instrument pointing due south.
It could only see the sky as it ‘passed’ the North /south meridian.
Stars remained visible for less than an hour.
Planetary bodies could not be followed.
The observer needed a whole team of assistants.
The telescope was not equipped with a ‘finder’.

Then the Potato Famine struck: it was a terrible time. The Earl could perhaps have given more relief than he did, but was by no means among the harshest of landlords.
Astronomical work was not resumed until 1848.

The climate of Ireland is not suited to visible light astronomy.
(Telescope site selection not really understood then).

The spiral morphology of the whirlpool galaxy was seen.

There were some better studies of the planets, especially Jupiter, but the telescope was not really suited for planetary observation.

He suggested that there were more galaxies than stars.
Sadly the telescope was never used together with photography or spectroscopy, probably because it could not track a faint object as the earth rotated.

He confirmed Herschel’s belief ‘that nebulae were collections of stars’
What objects were considered nebulae?
Gas & dust clouds
‘Planetary’ nebulae – stars surrounded by gas
Starry or ‘resolvable’ objects (galaxies in the modern sense) eg M31 in Andromeda
‘Irresolvable’ nebulae

Rosse did not have the tool to establish the distance of many of these objects, provided in 1908 & 1923 by the appreciation of the significance of Cepheid variable stars.

Was there any other Bradford connection?

Dr William Scoresby was once Vicar of Bradford.
He corresponded with Lord Oxmantown over the ownership of a Heaton schoolroom (said to have been occupied by Methodists).
The two men became friends.
Scoresby visited Birr several times and lectured on the telescope.
He expounded on its wonders in a USA lecture tour as early as 1847-48.

The Next Generation

William, 3rd Earl of Rosse, died in 1867 having received many academic honours. He and Mary had a wonderful life together: travelling, entertaining many important guests, and having their own yacht.

Mary long outlived William (by 18 years) living in Brighton and London (she was on poor terms with new countess).

She was a distinguished photographer herself.
She had been interested in casting iron gates, using the crucibles that once produced the mirror.
She also undertook relief work, and managed her Heaton & Shipley estates, as ‘the dowager countess’.

Their son, Laurence, the 4th Earl, was also an astronomer.
He gave the 36” reflector an equatorial mounting.
He measured the temperature of the moon’s surface using the 36” to focus radiation received onto a thermocouple – max. 197°F.
Laurence’s brother Charles developed the worlds first steam turbine powered ship. The ‘Turbinia’.

But who was Mary Ward?

Born Mary King in 1827.

She was a cousin of William, 3rd Earl of Rosse.

She frequently visited Birr (15 miles from her home).

She was a very well-known amateur astronomer and microscopist who met many astronomers and mathematicians herself.

Mary married Henry Ward, who lived off her income.
She also had eleven pregnancies.

Mary wrote many books on microscopy but died in a steam car road accident at Birr in her 40s.

The Birr telescope remained the worlds largest telescope until 1917.