Who was John Harrison?
Horologist who solved the measurement of the
Longitude or East - West reckoning problem by the invention of a
marine chronometer. Inventor of the Grasshopper mechanism
which would be stable at sea.
Date and Place of Birth:
31st March 1693, Foulby near Wakefield, Yorkshire,
England.
Family Background:
Son of Henry Harrison a Carpenter and mechanic
and eldest of five children.
Education:
Little formal education.
Chronology/Biography of John Harrison:
1700: The Harrison
family moved to the Lincolnshire village of Barrow on the Humber
where John becomes involved in carpentry. He had a fascination for
music and eventually became the local choirmaster.
1713:
John and his brother James decide to confine themselves to the repair
and refinement of clocks although they have been taught all sorts
of carpentry skills by their father. He built his first long case
clock entirely made out of wood.
1714: The English
Admiralty set up an award of £20,000 for anyone who could
provide seafarers with a reliable clock that, when used alongside
celestial sightings, could show their longitude at sea. At this
point mariners had to use dead reckoning whose unreliability often
lead to deaths. Clocks of this period where wholly dependent upon
weights and the earth's gravity for their operation. They could
not be used at sea due to the motions of the waves.
1725: Harrison
made the first of three precision pendulum clocks. He developed
the grid-iron pendulum which was made of
a grid of iron and brass that compensated for changes in temperature.
Their different rates of expansion cancelled each other out.
1728: The Harrison
brothers set to work on developing a marine chronometer to try and
win the prize. Harrison was introduced to George Graham another
clockmaker by the Astronomer Royal Edmond Halley
who was a great champion of his work. Graham lent him a large sum
of money so that he could continue his work once he saw the original
drawings for the marine clock.
1736: He demonstrated
the finished chronometer to members of the Royal Society who in
turn represented him to the Board of Longitude. This was the first
clock sent to them that they deemed worthy of a sea trial. Harrison
sailed to Lisbon on HMS Centurion and came back on HMS Orford. The
Captain of the Orford was particular praising of the design and
said that the H1 clock had placed them more accurately than traditional
calculations. The board refused to give the prize as it was not
the transatlantic voyage called for in the rules. Harrison set about
building H2.
1741: H2 was now
ready, but Britain had entered into the War of Austrian Succession
with Spain and it was not thought worth the risk of it being captured
by the Spanish. By now Harrison had discovered a design fault in
the bar balances. He was given a sum of £500 to tide him over
to the end of the war and with this he built H3.
1752: John
Jefferys built a precision watch from Harrison's own designs for
him.
1759: This
watch became his first marine watch or "Sea watch".
It is a 5.2" in diameter in silver cases and was known as Number
One or sometimes H4.
1761: The H4 model
proved to be the most accurate chronometer. The Harrison plan was
to not only design an internally accurate watch but one that was
also externally stable. On a testing voyage to Jamaica on HMS Deptford
the watch only showed a five-second error corresponding to an error
in longitude of 1.25 minutes, or one nautical mile. Again the Board
of Longitude refused to give up the £20,000 prize as they
believed the accuracy to be just luck. Outraged the Harrison's complained
and parliament then offered them £5,000 for the design which
they refused. Another trial, this time to Barbados was arranged.
The Reverend Nevil Maskelyne was also asked sail on HMS Tartar and
test the Lunar Distances system against the H4 watch. Again Harrison's
work was accurate to within ten miles.
1765: The results
were presented to the Board of Longitude and once again the Board
put it down to just luck. Once again complaints reached the ears
of Parliament. which offered an advance of £10,000 if the
Harrison's turned the design over to other watchmakers to duplicate.
H4 was given to the care of the Astronomer Royal to test on the
ground. Nevil Maskelyne had been appointed Astronomer Royal on his
return from the Barbados trip and therefore a member of the Board
of Longitude. His report of H4 was in the negative saying that as
it lost and gained some time each day it was inaccurate and refused
to certify it for the longitude problem.
1772:
The Harrison's complaints by now had reached King George the Third
who tested the new version H5 himself at the palace for ten weeks
of daily observations between May and July. He found it to be accurate
to within one third of one second per day. King George advised Harrison
to petition Parliament for the full prize after threatening to appear
himself to admonish them. Harrison finally received a reward of
£8,750 for his work but never received the full prize. (No
one else ever got the award either). Harrison's chronometers had
been used by Captain Cook on his charting of the southern Pacific
Ocean and one version was even carried on HMS Bounty to Pitcairn
Island with William Bligh.
1774: Harrison wrote
about his researches into the tuning of musical instruments and
the manufacture of bells.
Written Works:
- "Concerning such Mechanism".
- "A true and full Account of the Foundation
of Musick, or, as principally therein, of the Existence of the
Natural Notes of Melody"
Marriage:
1. 1718 to Elizabeth (died 1726).
2. 1726 To another Elizabeth.
Date and Place of Death:
24th March 1776, Red Lion Square, Holborn, London,
England.
Age at Death:
83.
Site of Grave:
St. John at Hampstead Churchyard, Hampstead
London.
Places of Interest:
LINCOLNSHIRE:
Turret clock at Brocklesby Park.
LONDON:
The National Maritime Museum, Greenwich has a
copy of K2 watch from HMS Bounty.
Royal Observatory, Greenwich has restored versions of H1, H2, H3
and H4 clocks.
Clock Museum, The Guildhall, Worshipfull Company of Clockmakers.
Science Museum
YORKSHIRE:
Clock in the billiards room of Nostell Priory
Leeds Museum and Art Gallery.
