1. Old Cooke; new perspectives
OLD COOKE;
NEW PERSPECTIVES
Can a make of refractor over 150 years old rival the quality of modern optics? Neil English looks at the
experience of a number of accomplished astronomers to discover the legacy of the Cooke refractors,
,,[To] our English Fraunhofer. .. whose science and skill We shall begin with the Reverend eight-inch (203mm) Cooke (that later
had restored to England the pre-eminent position she William Rutter Dawes (1799-1868), became known as the Thorrowgood),
held a century ago in the time of Dollond." revered among double star observers usually with a magnifYing power of
So wrote the mystery obituarist in 1868 concerning for bringing us his empirical formula 258x. His drawings, wrote Richard
the legacy of Thomas Cooke, master optician and used to work out the minimum Anthony Proctor, "are far better
founder ofT Cooke and Sons of York. It was a fitting aperture needed to resolve double stars than any others ... the views by Beer
accolade for a self-made Yorkshireman who had of a given angular separation. What is and Miidler are good, as are some of
re-established the prestige of Britain as great telescope less well known is that the Reverend Secchi's (though they appear badly
builders throughout the Victorian era and beyond. From was also a first rate planetary observer, drawn). Nasmyth's and Phillips', De
humble origins and with little formal training, Cooke apparently possessing extraordinary La Rue's two views are also admirable;
went on to build some of the frnest telescopes of his visual acuity. And he had an interesting and Lockyer has given a better set of
generation, including tlle giant 25-inch (635mm) Newall purchasing history, having used views than any of the others. But there
refractor, which briefly enjoyed the distinction of being refractors crafted by Dollond, Merz is an amount of detail in Mr Dawes'
the largest instrun1ent of its kind in the world. and MaJUer, Cooke and even the views which renders them superior to
Having had the pleasure of looking through a few shining light of An1erican optics, any yet taken." Camille Flammarion
Cooke refractors ranging in size from four inches (102mm) tile portrait painter turned telescope concurred: "The drawings by ...
up to ten inches (254mm), the images they served up never maker, Alvan Clark. Dawes brought a new precision to
failed to impress me. But were my views of the Cooke Yet, in the autumn of his life, old studies of Mars."
refractors 'coloured' or even 'representative' of what other 'Eagle Eyes' returned to a Cooke
observers have found? Curious to find out, I first explored refractor. Dawes had already made Red star delight
some of the comments of historical observers who had used some drawings of Mars in 1862 and at Across the Irish Sea, at a beautiful,
Cooke refractors during the course of their careers. earlier oppositions. In 1864, he used an windswept rural estate near Milltown,
341 Astronomy Now I July 2011

2. Old Cooke; new perspectives
six-inch telescope, and for many eight inches seems to be
the smallest aperture they'd be happy with. The Encke
division (marking) is typically regarded today as a good
target for a ten-inch instrument (for the record, I've
personally not seen it). So, was it the fme optics Raman
had in his five-inch Cooke, or exceptional eyes, or both?
I guess we'll never know for sure!
We return, once again, to England and to the
fondly remembered British actor and comedian WIll
Hay (1888-1949). Though playing the consun1mate
idiot on stage, behind the scenes Hay was a gentleman
of encyclopaedic knowledge, with a predilection for
astronomical adventure. He set up a fine six-inch Cooke
refractor in a private observatory established at his home
in Norbury, London, to study the planets. On the faithful
night of 3 August 1933, Hay used this instrument and an
eyepiece delivering a power of 175 x to detect a prominent
white spot on Saturn. The spot, located in the planet's
equatorial zone, remained prominent for a few days before
mysteriously fading away. Although similar phenomena
were recorded by earlier observers (Asaph Hall in 1877
and E E Barnard in 1903), Hay is credited with the official
discovery. Curiously, Hay's beloved six-inch Cooke, like
the spot he discovered, inexplicably disappeared after his
death and, despite diligent attempts to locate .it, we are still 11'I[i.
none the wiser concerning its current whereabouts! ~:
Modern perceptions
How did these refractors of old settle with folk who have
had the pleasure of using them over years and decades? First,
I contacted Douglas Daniels, President of the Hampstead
Scientific Society, England, who has had the iinmense good
fortune of using the observatory's six-inch £'l5 Cooke since
1967. Doug spoke to me about his background and how he
became acquainted with Cooke refractors.
"I have always been a keen lunar and planetary
observer and telescope maker since I first became seduced
by astronomy at the age of 13 in 1953," he says. "I joined
County Galway, John Birmingham (1814-1884) made ... A portable four- the British Astronomical Association [BAA] in 1956,
use of a 4.5 -inch (114mm) Cooke refractor to embark inch (102mm) fl15 which was the year of a very close opposition of Mars.
on a special study of red stars, in which he wished to Cooke refractor.
circa 1860, fixed At that time, I had built a six-inch Newtonian reflector
undertake a revision and extension of the best resource onto an original using a mirror made by the late Henry Wildey. I was q.,uite
of its day on such objects, Hans Schjellerup's Catalogue Cooke mount. impressed by the performance of this instrument, both on
of Red Stars. In all, he included 658 such objects. This Image: Richard Day.
Mars and Jupiter, but I was soon to meet another young
work was presented to the Royal Irish Academy in 1876 BAA member - Terry Pearce. Terry and I became good
and its merit was acknowledged by the award of the friends (and still are!). Terry had managed to borrow a
Cunningham MedaL In 1881 Birmingham discovered 4.5-inch Cooke from the BAA and had set it up in his
a deep red star in Cygnus, which is named after him. garden at Chingford in Essex. I was amazed at the sheer
He published articles on the transit of Venus and size of it. It was on the usual Cooke, two-part cast iron
sunspot morphology made with the same telescope, column and the equatorial mOlUlt was massive for an
corresponding regularly with the leading astronomers of instrument of that size. But I was even more amazed when
his day. A lunar crater is named in his honour too. I looked through it. The detail on both Mars and Jupiter
Moving next to the Far East, to Bankura in India, was astounding - far more contrast than with my six-inch
Chandrasekhar Venkata Raman (subsequently knighted), reflector. That was my first taste of a Cooke."
the recipient of the 1930 Nobel Prize in Physics for his
contributions to optical science, was fond of using a five-inch
(l27mm) Cooke refractor. I came across one curious account "AMATEURS HAVE BECOME SOMEWHAT
Raman made whilst using this telescope to observe Saturn: OBSESSED WITH OPTICAL QUALITY AND
" ... not only was the Crepe ring an easy object," he
BENCH TESTING, YET THESE ANTIQUATED
says, "But for nearly one hour while tl1e definition was
perfect, I made out Encke's marking in the A-ring and TELESCOPES CLEARLY HAVE THE POWER TO
held it steadily for practically the whole period." DELIVER THE READIES"
Now the Crepe ring is quite a difficult target for a

3. --- _- _- _- .._-- _- _-- _- _- _- _- - _-- -
I asked Doug how and when he first became
acquainted with the Hampstead six-inch Cooke.
"In 1967 I joined the Hampstead Scientific
Society and was able to use the six-inch Cooke at the
Hampstead Observatory," he says. "Again, 1967 was
a year with a good opposition of Mars, and the detail
observed with the Cooke was so good that I began
to attempt photography. I built a special planetary
camera with a flip mirror system to keep the planet
under close surveillance waiting for clear moments to
make exposures - it was a sort of single lens reflex job
but without the lens! [remember, this was 1967!]. My
photographs came to the attention of an American
student called Ron Wells, who was doing a PhD on
Martian topography at University College London. Ron
was working at the University of London Observatory
at Mill Hill - just 15 minutes from my-home. I was
introduced to the Director, Professor Allen, and was
allowed to use the 18-inch (457mm) Grubb - I had the
key to the big dome for six months. On the same site,
there were two smaller domes. One contained the Fry
Telescope - an eight-inch Cooke. Once again the Cooke
was the instrument that impressed most. On most nights
of average seeing, it could easily outperform the 18-inch
• Some of Doug Daniel's Grubb. Only when the seeing was excellent could the
recorded detail of the Martian Grubb show slightly more detail."
opposition of 1967. Image: Doug was more than happy to recount the
Doug Daniels.
telescope's long history.
"The Cooke was once owned by a member
called George Avenell," Doug says. "We know that
it was in use at the observatory in 1923. It was finally
presented to the society in 1928. Prior to this we have
no information. The optical tube appears to have
been manufactured around 1900, but we have no hard
evidence for this date. When I began using it in 1967,
it was mounted on an old Cooke equatorial from a
4.5-inch instrument that was too small. It had the old
Cooke falling weight drive and a worm sector, not a
complete wheel that was always getting jammed. In
the end we built our own heavy-duty mount in 1976,
driven by a stepper motor. A couple of years ago, I was
in correspondence with Martin Mobberley, who was
researching the six-inch Cooke once owned by Will
!l./.ool..,
Hay. I was able to confirm that the Hampstead Cooke
'-;,.J.. O·Q ,.,._ ~ )( 3
was not Hay's instrument."
F.P. 3 e~E.t Sec..
What about the telescope's maintenance? Is it, in
"'.."..J~ ~o "";"'s ....Q f'I>du",.
any sense, fastidious in its requirements? "Not at all,"
says Doug. "The objective is best left well alone. It gets
an annual wipe over with meths and a lint free cloth and
every few years is checked for squaring on, which hardly
'lS/4/Q needs any adjustment for long time periods. That's
t>1I."'''''"<j .. pl,()fO<j"fh another nice aspect of refractors - they are virtually
t4..... S<......... Q'4Si.", maintenance free, unlike reflectors which are constantly
~h."
0 ....
~1.1<:l going out of square and need re-coating every few years."
~~ "l.J. IS· "~I() b...J.O.q..
Ph"'" t 10<. ." fP· -S f'.I'~l A new eye on an old telescope
~cN"'" 'l5-~~
De ... f'l!Q
Next I canvassed the opinion of Dr Richard McKim,
Director of the Mars Section of the BAA, who has
used Cooke refractors in his extensive studies of the
red planet over the last few decades. "I have used many
refractors on a regular basis since the 1970s," explains
McKim. "The problem is, I have no basis of comparison
with other makes. Until 1988, the Northumberland
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