John Wall biography.
John Wall was born in Crayford Kent on the 26th
of June 1932.
At the age of one his parents moved to the
adjacent town of Dartford Kent, two miles away, where John lived
for the next 60 years.
His father was educated working class having won
a scholarship for the local prestigious Grammar school , where he
majored in chemistry and French, however the elitist system of the time
precluded him from going on to university, and he went into
industry training as a universal miller in the engineering shops of
Vickers Armstrong Crayford. John, s mother had trained as a
nurse and worked at a large hospital outside Dartford.
His father was an enlightened man and bought the
house where john lived in an era where working class people only
rented. John's early life was turbulent as at the age of seven the
second world war broke out, and at that tender age he was
evacuated to Launceston in Devonshire for nearly two years, his life on a
farm there became a formidable education experience, as he was
curious about everything he saw on the farm and in the
open countryside about.
However his formal education was indifferent as
the school system for evacuees in the country was very
poor.
In 1942 he returned to Dartford after the worst
of the "Blitz" was over, but experienced many air raids, the flying
bombs, and the fall of V2 rockets near the end of the war, to him a very
exciting childhood.
He went on to secondary school and during this
time his interest in engineering blossomed, he read all of his father's
engineering books and expressed his interest in designing aero engines
and making models of them.
He also discovered Astronomy which
became a lifelong interest , also he became an avid reader of science
fiction; much of his mind was influenced by the scientific romances of
HG Wells.
At this time John's skill as a constructor
became evident and he became an avid model builder.
He could have sat the eleven plus for the
Grammar school, but at that time places were only awarded to those
on a rota system. John left school at the age of
fifteen and joined Vickers as a shop boy working on milling
machines as a minder, at sixteen he sat and passed the apprenticeship
exam and finally went to college on the day release system during his
training.
John broke into his apprenticeship to do his
national service and served in what was then Malaya in the fight
against Communist terrorists.
During John's early training with the army, he
went to the Festival of Britain , and in the Dome of discovery saw
the 72 inch Grubb Parsons reflector due to be sent to Siding springs in
Australia, this surprisingly evoked nothing more than intelligent
interest, but on one of the terraces inside the dome he saw a
twelve inch Newtonian on display, and 'caught fire' : this was what he
wanted to do with his life, build a similar telescope and more.
He had had a casual interest in telescopes as an
amateur astronomer, and built a refractor from spectacle lenses, but
not the sudden burning interest he experience at the exhibition.
During his army career he obtained books on
optics and telescope making.( Ingalls ATM books 1 and two ), and
digested them whole, also working up some designs for his first
telescope, a six inch Newtonian.
John left the army and resumed the final year of
his apprenticeship.
During his period he built his first six inch
scope; grinding and figuring the mirror, and building the scope
out of recycled materials; in 1953 there were no materials to be
obtained and John haunted rubbish dumps around Dartford to
scrounge suitable metal.
After the six inch he became really ambitious,
and purchased the crown and flint blanks for a six inch refractor from
Chance Pilkington.
This proved to be a baptism of fire, and it took
him a year to bring to figure the lens to his satisfaction.
When he built the scope he observed the sky at
nights to familiar himself with the heavens, taking in nebulae planets
moon, double stars and everything else, he accidently found Uranus
after pointing the scope roughly in the direction the planet should be,
and there it was, dead centre in the field, so he shifted the scope in
order to find his way to the planet, and it took him half an hour to get
it again.
He observed comet Arend Rowland, and
did a detailed drawing.
Around this time he joined an
Astronomy evening course at the Crayford Manor house adult
education centre, here he met Dr. Wilkins the noted selenographer, who
was conducting the course, John told him about the refractor and he was
impressed, and he arranged a meeting with the principle with a view that
John should construct a six inch Newtonian for the centre teaching
course.
John said he would build twelve inch, and the
project snowballed, and expanded; there was an
old boiler house on the grounds that could be demolished and a roll off
observatory built from the recycled material.
A grant was obtained to do the work and
John built the twelve inch Newtonian.
Now this was considered to be a huge telescope
in those days and it got the notice of Sky And Telescope, who featured
it in one of the magazine issues.
Thus started John's long career with the
Crayford Manor House.
Meanwhlle, John languished in the
workshops at Vickers doing boring repetitious work, when he wanted
to be creative, then the management launched a scheme to recruit
droughtsmen from " the ranks", and as John had finished his apprenticed
ship and done the National Certificate course at college he applied and
was accepted into the drawing office as a junior draughtsman.
He was immediately put on a team that was
redesigning a machine from a parent company in America, for
production at Vickers. At this stage he started to show flair for
solving problems and considerable design capability, and within two
years in the drawing office he was made a designer.
John had many years in the drawing office until
the firm went on the wane, he was transferred to the office of the Works
engineer and had his own little drawing office, where architectural and
services plans for the factory were kept.
The work was light and he had time on his
hands.
He had already finished a twenty inch alt
azimuth reflector and was currently making a thirteen
and a half inch F:4 sky sweeper, the mirror was once a tool for a
sixteen inch singlet objective lens for his dialyte
experiments.
The scope lacked a rack and pinion focuser, and
those available were very bad.
One sunny September afternoon in 1969, he sat in
his office and pondered how he could make a rack and pinion mount, then
inspiration came out of the blue; why not mount the
eyepiece tube on four rollers and press a smooth focusing pinion onto
the top of the tube midway between the rollers, he was familiar with the
principles of kinematics and knew that the focusing tube would have
only two degrees of motion, with no side wobble or sticking, in fact the
tube would be located precisely, and would not depend on the clearance
of the tube and the bush that it would have to slide in.
The next inspiration then came, why
not make the support bracket for the pinion swing up on a hinge in order
to allow the release of the focusing tube so that it could be
exchanged for another containing an eyepiece of a higher or lower
power, which could be done in the dark quickly and easily.
Sketches and a construction drawing were made
and John started right away to construct a prototype in his own
engineering workshop.
In two days it was finished, and it was a
winner.
He demonstrated the focuser to the Crayford
Manor House astronomical society, and the secretary suggested that
he write it up for the Journal of the British Astronomical
Association, John had newly joined the association, and this was to be
his maiden paper.
It caused a sensation, and everybody jumped
onto the band wagon, and made varying versions and named them
after their own particular society, however John had named the device
for his place of birth and his society, and the name has stuck as the
Crayford focuser, although he had originally named it the Crayford
Eyepiece mount, or CEM.
About this time John had started research into
dialyte refractors, using optical bench cum telescope devices and a math
he had developed to compute the degree of chromatic aberration in the
system and how to suppress it In 1970 he had developed a classical
ten inch dialyte where the flint was placed half way down the
focal length, this needed a doublet achro lens of five
inches aperture in order to recover the virtual achromatic the
system formed, the scope was a success and John used it for many years
for lunar observations , later he found out that he had reinvented the
Petzval telescope.
A couple of years later the firm folded and John
was made redundant.
He decided at the age of 39 to give up
engineering and do something different, he obtained a job as a lab
technician at the very Grammar school that his dad went to and he
didn't.
He spent seven very happy years there, during
which he built the 24 inch Cassegrain equatorial telescope for the Manor
house, which replaced the old twelve inch, this telescope is now the
flagship telescope of the Crayford society. At this time John
was accepted as a fellow of the Royal Astronomical
Society.
John left the grammar school and joined the
National Maritime museum at Greenwich to work in the education
department and as an optical engineer to the Old Royal
Observatory.
John was also one of the night assistants for
the 28 inch refractor, and got to use the telescope many times during
his tenure there.
He remained with the NMM for about seven years
and was made redundant during massive cut backs in
Government funding, he was offered early retirement at 55, and took it
with a pension. John was now free from the need to work for a
living, and settled down to telescope making full time.
John also joined the Open University and read
for his Bachelor of Science degree , and graduated in
2004.
During the next few years John made a thirty two
inch compound reflector of his own design, which was mounted on an alt
az mounting, but this was unsatisfactory, and he rebuilt the scope as a
fork mounted equatorial, the scope was a light bucket and was designed
to feed flux into a photoelectric photometer array for the
Crayford society who were doing this research at the time, the scope
was to go to Crayford's dark site, but this project fell
through and the scope was eventually dismantled.
John worked on an even more ambitious 42 inch,
and the completed scope was a mechanical engineering
success; the whole one tonne scope could be moved with one finger,
however, the thin mirror failed, and it too was dismantled, all but the
alt az mounting, this was kept for the most ambitious project John was
to undertake in his whole career.
During the nineties John started investigating
retrofocally corrected dialytes, he had immediate success with this new
system, and developed a ten inch scope for testing, the results from
this encouraged John to realize a life's ambition, to make a very large
refracting telescope.
Now a 'retro dialyte' is one stage beyond
the Schupmann Medial, which is a catadioptric system, John's system is
all pure refracting optics.
The new system can be described as a terrestrial
telescope with a singlet objective lens, and the erecting lenses are
overcorrected to compensate for the chromatic aberration of the
singlet OG.
It bears absolutely no resemblance to a
Schupmann!
John started on the thirty inch refractor
project in the late nineties, he ground the thirty inch objective lens
on a special machine built for the job.
He then made two folding flats, one 22 inches
diameter and the other 12 inches.
He set up the optical system upstairs in the
house, looking through a bedroom window at objects ten miles
away.
John then spent several weeks perfecting the
correction lenses for this system, using a special optical bench
in the optical train of the telescope
Over the next eighteen months he built the
refractor in the back garden.
He offered the refractor to the Hanwell
Community Observatory near Oxford, where it remains to this
day.
John moved up to Coventry, and there met
and befriended Peter Wise, a professional
telescope maker, and John took him along to Hanwell to see the 30 inch
refractor, Peter was immediately enthusiastic about the concept,
and said he wanted to build the telescope commercially.
John then coached Peter through the first stages
of the optical design concept and then left Peter to develop the
first commercial product, thus the "Zerochromat" was born, and
John suggested the name for the scope.
So culminated the telescope career of John Wall,
he has built many telescopes in his time and other optical
instruments.
He now investigates and experiments with exotic
refractors concepts, and has discovered the very controversial
Hypochromatic refractor.
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