Chronography of Metrology
Page last
modified 25 September 2023
There is one kind of robber whom the law does not
strike at, and who steals what is most precious to men: time.
Napoleon Bonaparte
See
also Science and Technology for other related timelines.
See also Price-Currencies for historic weights
and measures
See below for Measuring
Time and Dates
21 January 1962� The Meteorological Office
started using Centigrade as well as Fahrenheit.
1960, The 11th
General Conference on Weights and Measures replaced the physical metre with a
definition based on radiation from Krypton-86. In 1983 this was changed again
to the distance light travels in a specified time.
1954, The 10th
General Conference on Weights and Measures added a fourth basic unit, the Kelvin as unit of temperature (see
1889).
1889, The first General
Conference on Weights and Measures established international prototypes for the
metre and kilogramme. Together with the second as unit of time, these became
the three base units of measurement. See 1954.
1875, The USA signed the Treaty of the Meter, along
with 16 other nations. However efforts to institute the metric system in the
US, between 1896 and 1907, ran into major opposition and were cabandoned. By
the 1930s, economic issues took precedence and metrication was forgotten in the
USA. The advent of the Space Age in the 1950s revived the issue, but it has
still made no progress.
1850, The metric system began to
spread worldwide. It was now in use in Greece, parts of Italy, The Netherlands
and Spain. By 1880 17 more countries had adopted it, including Austro-Hungary,
Germany, Norawy and most of South America. 18 more countries took it up by
1900l.
1848, William Thompson, Lord Kelvin,
established absolute
zero as -273 C.
1 January 1840, The metric system became compulsory in
France, following an 1837 law to this effect.
7 April 1795, France officially adopted the metric system of
measuerement. However in 1812 Napoleon Bonaparte brought some pre-metric units
back into use.
30 March 1791, The metric system of measurements was proposed in France.
1785, Watt devised the �horsepower� as a unit of work.
30 April 1772, The first
dial weighing machine was patented by John Clais in London.
1761, The first marine
chronometer that was accurate to within half a minute per year was made by Paul
Harrison, England.
25 April 1744, Anders Celsius, Swedish astronomer who devised the Centigrade
temperature scale in 1742, died.
16 September 1736, The German scientist Gabriel Fahrenheit, who devised
a scale of
temperature, died.
1720, Fahrenheit invented the mercury thermometer.
27 November 1701, Anders Celsius, Swedish astronomer who devised
the Centigrade
scale of temperature in 1742, was born in Uppsala.
1700, Fahrenheit invented the alcohol thermometer.
24 May 1686. Gabriel Daniel Fahrenheit,
the German
physicist who invented the mercury
thermometer, was born in Danzig.
Pierre
Vernier. 1580 - 1638
14 September 1638, Pierre Vernier,
French engineer, died in Ornans.
1631, Pierre Vernier invented the Vernier Measure, in which a slider is
used to increase the accuract of the distance measured by a factior of ten.
19 August 1580, Pierre Vernier was born in Ornans, France. In
1631 he described his invention for precision measurement, known as the
Verniuer Scale.
14 July 1610, Ferdinand II, Grand Duke of Tuscany, was born
in Italy. In 1641 he invented an improved thermometer.
1305, The English acre was
defined by statute as 4,840 square yards.
1101, In England, King Henry VIII
introduced the yard as a measure of
length, the length of his arm.
789, Charlemagne introduced the Royal
Foot as unit of length and the �Karlspfund� as unit of weight, equivalent to
365g or about 13 oz.
2000 BCE. Mesopotamia possessed a standard system
of weights and measures. The Shekel
consisted of 129 grains (8.36 g), and the Mina,
60x as large, were in use by 2400 BCE. By 2000 BCE the Mesopotamians also used
the log (0.541 litres, or 33 cubic
inches), the homer (720 logs), and
the cubit and foot. The cubit was
about 18 inches, the distance from the elbow to the tip of the middle finger.
3100 BCE, Cunieform writing
developed in Mesopotamia; temple records and accounts kept.
Measuring
Time and Dates
1 March 1983, Swatch watches went on
sale. Made in Switzerland, they were an attempt to recapture some of the market
lost to Japanese watch makers. The name meant �second watch�, a fun accessory
rather than an upmarket watch.
1969, The first quartz
wristwatches went on sale, in Japan.
1968, The picosecond, or one ,millionth of a
millionth of a second, was first measured by Bell Laboratories, USA, using a
single laser pulse.
25 October 1960, The Bulova Accutron tuning fork watch,
introduced this day, had a tuning fork that vibrated 360 times per second, 144x
as fast as the balance oscillators in other hand wound conventional and
electrical watches. It was the most accurate watch to date, keeping time to
within 1 minute pre month.
2 January 1957, The Hamilton Watch Company
introduced the first battery powered
watch.
Atomic clocks
1967, The 13th
General Conference on Weights and Measures changed the definition of a second
from 1/86,400 of an average solar day to a number of radiation cycles produced
by a Caesium-133 atom.
22 January 1965, The US Army announced it
had developed an atomic clock capable of measuring 1,000 millionth of a second,
1962, An atomic clock was made
that was accurate to 1 second in 100,000 years.
24 August 1955, The first microwave
atomic clock was unveiled at the National Physical Laboratory, Teddington, UK.
It was accurate to one second every 300 years. By 2020
atomic clocks were accurate to in second every 300 million years.
1948, The first atomic
clock was made. This nwas the ammonia
clock, and kept time by the speed at which nitrogen atoms in an ammonia
molecule vibrated.� It was superseded by
the caesium clock, accurate to one
part in ten billion. In turn this was superseded by the hydrogen maser clock, accurate to one second in 1.7 million years.
1935, Dendrochronology, counting
tree rings to estimate dates, was developed by AE Douglass,
1928, The first quartz crystal
clock was made.
14 February 1918, The Soviet Union adopted the Gregorian
Calendar.
7 July 1923, John Harwood patented the first self-winding
wristwatch. Self-winding watches already existed but they were bulky
fob-watches. The concept was to use a small swinging weight to wind the
timepiece.
21 March 1915, Frederick Winslow Taylor, the inventor of modern scientific
time-management, died.
13 October 1884. Greenwich was adopted as the universal time
meridian from which world longitude is calculated.
13 March 1884, Standard time zones were established in the USA.
20 March 1856, Frederick Winslow Taylor, the inventor of modern scientific
time-management, was born.
1820, The British Royal Navy
ceased to use half-hour sandglasses to keep the time.
24 March 1776, John Harrison, watchmaker and inventor of the chronometer, died in London.
3 September 1752. The date changed this day to 14
September 1752 with the introduction of the Gregorian Calendar. See 5 April
1753. See also 5 October 1582, start of Gregorian calendar. Crowds of people
protested, believing their lives had been �shortened� by 11 days (days 3-13
September 1752 inclusive did not exist).�
The old calendar had a leap year
every 4th year, and therefore was 365.25 days long.� However the calendar had now got out of step
with the real year.� The new calendar
omitted leap years every century, unless the year was divisible by 400. See 1
January 45 BCE.
1 January 1752, Officially the first �new year� to fall on 1st
January; previously the new year had begun on 25th March.
8 July 1695, Christiaan Huygens, the Dutch scientist who
invented the pendulum clock, died
(born 1629).
24 March 1693, John Harrison, English horologist, was born in
Foulby. In 1715 he constructed an 8-day clock.
1680, Clocks began
to have minute hands. By the mid 1700s second hands were also in use.
December 1656, The pendulum
clock was invented by Huygens.
1 January 1622, In the Gregorian Calendar, January 1 was
declared the first day of the year, instead of March 25.
17 June 1584, The Catholic States of the Holy Roman Empire, also
the Catholic cantons of Switzerland, adopted the Gregorian Calendar.
5 August 1540,� Joseph Justus
Scaligier was born in Lot et Garonne, France. In 1583 he devised the
Julian Day Count, which set 1
january 4713 BCE as day 1. This makes, for example, 1 January 1990 as Day
2,447,527.
1509, The earliest watches were
invented by Peter Henlein of Germany; they were named �Nuremberg Eggs�.
Clocks with
dials and hands, that strike the hours, appear
1386, The first public clock in
England was installed, at Salisbury Cathedral.
1353, The first known public clock was erected, in Milan,
Italy.
April
1352, A
weight-driven mechanical clock that struck the hours was in use in Windsor, England.
1350, The oldest known alarm
clock was made in Wurzburg, Germany.
1335, The first clock to strike
the hours was made in Milan, Italy.
1325, The first clock with a
dial was installed at Norwich Cathedral, England.
890, Marked candles were used
in England to measure time.
725, Chinese Buddhist monk I-Hsing
developed the escapement mechanism
crucial to modern watches, some 600 tears before similar devices were used in
Europe.
159 BCE, The first water clock (clepsydra),
in Rome.
The Roman
Calendar
1 January 45 BCE, The Julian
Calendar, introduced by Julius Caeasar (reigned 63-46 BCE), began. In
46 BCE Caesar
reformed the Roman Calendar. Advised by the Alexandrian astronomer Sosigenes,
he first added 67 days to the current year, to compensate for the missed
intercalary months (see 700 BCE). This year was therefore 445 days
long. The Roman year now contained 365 days, with an extra day added every 4
years to make up then then-known solar year of 365.25 days (see 3 September 1752).
The month lengths were rearranged to consist of 7 31 days, 4 30 days, and one
of 28 or 29 days. Quintilis month was now renamed Julius in Caesar�s honour.
However the Roman priests erroneously added the ;eap year every three years, so
that in 8 CE Emperor
Augustus reformed the calendar again by skipping several leap years
to restore the months to their proper place in the solar year. The month
Sextilis was then renamed Augustus in his honour. This basically set the calendar as we know it today, with
the exception of the Gregorian reforms
from 1582 necessary because the solar year in fact fell just short of 365.25 days,
making ther true date of Easter hard to calculate.
Julius
Caesar
introduced the Julian Calendar. The Julian 365-day calendar was based upon the
Egyptian calendar, and replaced an earlier 355-day calendar used by the Romans.
The Roman year began in March, and the 5th month, Qunitilis, was renamed July
after Julius
Caesar himself. Augustus then named the 6th month after
himself, too. The Calends was the first day of the month, and in longer months
of 312 days the Nones were on the 7th and the Ides on the 15th. In shorter
months the Ides and Nones fell on the 5th and 13th days. The Romans also used
an 8-day week with the days lettered A to H. For a while this co-existed with
the 7-day week, based on the Sun, Moon and 5 visible planets. In 321 AD Emperor Constantine
ruled that the 7-day week alone was to be used.
700 BCE, The original Roman
calendar had ten months, plus around 60 days not included in any month. This
calendar began on the Spring Equinox, known as Martius I. The nxt nine months
were called Aprilis, Maius, Junius (these first 4 months after Roman gods),
then Quintilis, Sextilis, September, October, November and December, after the
words for numerals 5 to 10. Then came the days of winter which had no month
name or set number of days and could vary in legth to make the entire year come
to 360 days. This
variation arose because the High Priest in charge of the calendar could add or
subtract days from the ten months as he saw fit, for political gain.
In 700 BCE Numa
Pompilius, 2nd King of Rome, attempted to introduce some
consistency by instituting the two months of February and January (Januarius,
named afte the god of doors, the start of the year). In 150 BCE the order of
these two� months was reversed.
Pompilius knew that the year was
about 365 days long, and that the liunar cycle was 29.5 days; 12 liunar cycles
came to 354 days. He decided on 12 months, 4 of 31 days, 7 of 29 days, and one
of 28 days, so as to stay as close as possible to the lunar cycles. The Roman
calendar now consisted of Martius (31), Aprilis (29), Maius (31), Junius (29),
Quintilis (31), Sextilis (29), September (29), October (31), November (29),
December (29), February (28) and January (29), totalling 355 days. This fell
short of the solar year by 10 days, so every other year a thirteenth month., Mercedinus,
22 or 23 days long, was added coming after Febriary 23 or 24, so years were now
355, 377, or 378 days long. However the High Priest was still in charge of deciding
the insertion and length of the extra month, and could still manipulate the
calendar for political advantage. The intercalary month could be
omitted completely, and in the reign of Julius Caesar, 63-46 BCE, just 5 such months
had been added instead of the expected 8. Hence Ceasar�s reforms, see 1 January
44 BCE.
3500 BCE, Earliest sundials
(obelisks) in use, in Egypt.
4241 BCE, The Egyptians developed a
calendar with 12 months of 30 days plus 5 extra days. This was their Year One.