James Gregory

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James Gregory
Scotland's Isaac Newton?

• A new view of the Universe V
• Fred Watson, AAO
• April 2005

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Gregory's Travels
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Born Nov. 1638, Drumoak Manse (near Aberdeen)
Fit like the day?
Aberdeen
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Education
Around 1653, James entered Marischal College,
Aberdeen Founded 1593, rebuilt c.1750
United with Kings College in 1860
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While at Aberdeen
James studied the science of optics and new
ways of making telescopes Moved by a certain
youthful ardour I have girded myself with these
optical speculations,chief among which is the
demonstration of the telescope. (preface to
Optica Promota, 1663)
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London, c. Nov 1662Feb 1663
James travelled to London to oversee the
publication of Optica Promota. He made a brave
attempt to build the first reflecting (mirror)
telescopeof which more later. But he was anxious
to be off to Paris to meet the great Dutch
mathematician, Christiaan Huygens, and left it
unfinished.
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Italy, c. May 1663May 1668
James missed Huygens in Paris and had to be
content to leave a copy of Optica Promota for
him. He then went on to his main destination, the
University of Padua.
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Padua
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While in Padua
James studied under the Professor of
Mathematics,Stefano degli Angeli (himself a
former pupil of Torricelli and Cavalieri) until
May 1667. His own mathematical studies took on a
new and original dimension, and he independently
laid the foundations of the calculus (which is
usually attributed to Newton and Leibniz). He
published two books of great brilliance
Veracirculi (1667) and Geometriae pars
universalis (1668).
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Back to London
Gregory returned to London in May 1668 to find
that Vera circuli had been well-received. He was
fêted by the scientific community because of his
up-to-date knowledge of Italian science. James
was elected a Fellow of the Royal Society on 11
June 1668.
Gosh, it was nothing, really
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Royal intervention?
King Charles II seems to have been persuaded
byJames fellow countryman (and fellow member of
the Royal Society), Sir Robert Moray, to found
the Regius Chair of Mathematics at the
University of St. Andrews.
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Off to St Andrews
James arrived at St. Andrews late in 1668.
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Gregory at St. Andrews
James in the Upper Library with his clock (by
Joseph Knibb, 1673.)
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Observing the stars
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Gregory and the diffraction grating
James was intrigued by the behaviour of light as
it passed through the feather of a sea-bird. He
had demonstrated the first diffraction grating.
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BUT
In this, as in all his work, James deferred to
his younger contemporary, Isaac Newton
(1642--1727). I would gladly hear Mr Newtons
thoughts of it. And that was his main problem.
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Attitudes at St. Andrews
James was disappointed with the support
hereceived at St. Andrews I am often troubled
with great impertinences I was ashamed to
answer, the affairs of the Observatory of St.
Andrews were in such a bad condition, the reason
of which was, a prejudicethe masters of the
University did take at the mathematics So he
left.
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And, in 1674, went to Edinburgh
In October 1675, James was observing the moons of
Jupiter with his students. He suffered a stroke,
and went blind. A few days later, he died. He was
36.
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A modern assessment of Gregory
He was the only one of Newtons contemporaries
who could match him in mathematical breadth and
profundity. But For all his talent and
promise of future achievement, Gregory did not
live long enough to make the major discovery that
would have gained him popular fame. (D.T.
Whiteside, 1969.)
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Gregory and the Telescope
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The origins of the telescope
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Lens telescopes in the 1660s
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There had to be a better way
In contrast, mirror telescopes developed entirely
in the heads of the mathematicians of the day.
Most notable were Réné Descartes (1596--1650)
and Marin Mersenne (1588--1648)
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Gregory suggested combining mirrors and lenses
The problem was that no-one could make a mirror
good enough for a telescope.
The reason why is due to basic optics
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Niccoló Zucchi had attempted to make a reflecting
telescope back in 1616
It didnt work.
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Why not?
Its 6 times harder to make an accurate mirror
surface than a lens surface. (Prove it with the
bathtub test)
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In 1668, Newton won the day
Despite Gregorys efforts in 1662 with the
optician Richard Reeve, he didnt quite make his
telescope work.
Gregory had thought it not worth the pains to
trouble myself anie further with it, and headed
off to Paris.
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But eventually, Gregory prevailed
Appropriately, it was the Edinburgh optician,
James Short (1710--1768) who eventually perfected
the Gregorian telescope.
And, in passing, made his fortune.
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And, of course, the rest is history
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James Gregory
Scotland's Isaac Newton?
The End