Edmund Halley
1656-1742
His life
Halley was born in a
soap-maker family in
Haggerston, England,
in 1656 (four years
before the Restoration
of Charles II).
Since he was a child he
showed his interest in
Maths.
Education
Halley attended St. Paul’s School in London,
then he went to Queen’s College (Oxford), and
in that period he was introduced into the
Royal Greenwich Observatory.
After some travels around the world with the
East India Company, in 1678 he was elected a
fellow of the Royal Society and, with the
intercession of the King, was granted the M.A.
degree from Oxford University.
First works
In 1684 he helped Newton in the development of the
theory of gravitation; he therefore tried to solve the
problem of the planetary motion with Robert Hook
and Sir Christopher Wren.
Mathematics
Edmond greatly improved the
theory of equations in algebra,
the doctrine of logarithms and
the property of sections of a
cone.
While a professor at Oxford Edmond
published important editions of the work
of Apollonius of Pega and of other ancient
geometricians.
Mathematics helped him also in his
astronomical studies.
Travelling abroad
After some sea voyages
undertaken for purely scientific
purposes (first in History!!), it
was Halley who published the
first meteorological chart in 1686
using an isometrically
representation. He also
introduced a rudimentary
working model of a magnetic
compass.
After his voyages…
When he returned he published some
studies about winds and monsoons, and
he also identified the cause of
atmospheric motions: the solar heating
Some strange studies!
In 1691, Halley built a
diving bell, a device in
which the atmosphere was
replenished by way of
weighted barrels of air sent
down from the surface.
And with it he and 5
companions dived to 60feet
in the Thames for one and a
half hour.
Statistics
Edmund Halley, in 1693, was the first to
employ correct mathematical methods to
calculate a life table (invented by John
Graunt), but he first became interested in
the vital statistics in Paris around 1680.
He used vital statistics collected by
Caspar Neumann of Breslau
(“Reflexionen über Leben und Tod bey
denen in Breslau Geborenen und
Gestorbenen”).
How can we calculate a life table???
A life table is easy to calculate if
the mortality rates are known for
each year of age. Starting with an
arbitrary large number, say 1,000,
of newborn, the number surviving
to age one year can be estimated
from the mortality rate in the first
year of life. Then the number
surviving to the age two years can
be estimated using the mortality
rate in the second year of life, and
so on.
Halley’s work in statistics was the first step towards the
theory of annuities, life insurance and the actuarial
profession, in fact he was the first to mathematically
and statistically rigorously calculate premiums for a life
insurance policy.
But what’s an actuary???
Actuaries mathematically evaluate the likelihood of
events and quantify the contingent outcomes in order to
minimize losses, both emotional and financial,
associated with uncertain undesirable events.
Voyages and magnetism
Between 1698-1700 Halley was
commissioned as a naval captain and he
actually commanded a Royal Navy manof-war, the Paramour, making two
prolonged and eventful ocean voyages.
After that he pubblished the first magnetic
charts of the Atlantic and Pacific Ocean
The Halley’s Astronomy
Continuing his pioneering work in
observational astronomy, Halley published
in 1705 A Synopsis of the Astronomy of
Comets, in which he described the parabolic
orbits of 24 comets that had been observed
from 1337 to 1698. He showed that the three
historic comets of 1531, 1607, and 1682 were
so similar in characteristics that they must
have been successive returns of the same
visitant—now known as Halley’s Comet—
and accurately predicted its return in 1758.
The Halley’s Comet!
Other studies of Astronomy
Halley predicted with considerable accuracy
the path of totality of the solar eclipse visible
over England in 1715. After a long and careful
study he was the first to realise in 1693 that the
Moon's mean motion had a secular
acceleration. An apparent gradual acceleration
of the Moon's motion in its orbit, as measured
relative to mean solar time. He was the first to
predict extraterrestrial nature of the precursors
of meteors.
He was the first to
suggest that
observations of
transits of Venus
could be used to
measure the distance
of the Sun.
Against Greek’s astronomy
In 1718 he discovered
the Proper motion
of the "fixed" stars by
comparing his
astrometric
measurements with those
given in Ptolemy's
Almagest, so he offered
the first proof of motions
of starsby showing that
they had moved since
Ptolemy’s time
Relation between proper motion and velocity components of an object. At
emission, the object was at distance d from the Sun, and moved at angular rate
μ radians/s, that is, μ = vt / d with vt = velocity transverse to line of sight from
the Sun. (The diagram illustrates an angle μ swept out in unit time at
tangential velocity vt.)
The last years
Halley succeeded John
Flamsteed in 1720 as
Astronomer Royal, a
position Halley held until
his death in 1742 at the age
of 85. Halley was buried in
the graveyard of the old
church of St. Margaret (now
ruined).
THE END