Time Tellers

The following are some landmarks in the history of telling the time :

• 1500-1300 BC Sundials are used in Egypt : as the Earth rotates, the gnomon - the upright part the sundials - casts a shadow which moves to indicate the time.
  
  
• c 400 BC Water clocks are used in Greece : as water drains from a container, each level it reaches represents a period of time.
• c 890 In England, people used candles marked with time intervals.
• 12th century The hourglass, familiar to us as an eggtimer, is used by monks to show times of prayer.
• 1325 The first clock with a dial is installed in Norwich Cathredal, England.
• 1335 The first clock to strike the hours is made in Milan, Italy.
• 1350 The oldest known surviving alarm clock is made in Wurzburg, German.
• 1364 Clocks are first used in people's homes.
• 1386 Salisbury Cathredal's clock is insdtalled. This is the world's oldest clock in working order.
• 1462 The earliest description of a watch is written in Italy.
• 1641 The idea of the pendulum clocl is proposed by Vincenzio Galilei, son of the famous astronomer, Galileo.
• 1657 The first pendulum clocks are made in Holland.
• c 1665 The first watches with minute and second hands are made.
• 1759 John Harrison's marine chronometer is made. Accurate timekeeping at sea is important for calculting position, but previously the rollin gof a ship had made it impossible.
• 1880 Greenwich Mean Time becomes the standard from which time around the world is set.
• 1880 The first practical wristwatches are made for the German navy.
• 1928 The first quartz crystal clock is made.
• 1949 The first atomic clock is built.
• 1947 The first battery watches are marketed in the USA.
• 1969 Quartz wristwatches are first sold in Japan.
• 197o Digital watches and displays become widely used and can be made and sold cheaply.
• 2006 40 radio clocks around the world transmit signals that enable people to set their clocks and watches accurately.

Taken from : Whitaker's World of Facts, page 12.

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The Universe in a year!

The American astronomer Carl Sagan (1932-96) first suggested a "cosmic calendar" as a way of helping people understand the history of the Universe. He put everything into the scale of a calendar year: the galaxies are formed over nine months and the Earth appears in September. All human history is crowded into the last five minutes of the last day of the year. Recent time has to be divided into seconds and fractions of a second. So everything that happened over the last 475 years takes place in less than the last second of the last minute of the year.

DATE / TIME and EVENT
1 Jan (midnight) : Big Bang - Universe forms

15 Mar : First stars and galaxies form
1 May : Milky Way galaxy forms
8 Sep : Sun forms
9 Sep : Solar system forms
12 Sep : Earth forms
13 Sep : Moon forms
20 Sep : Earth's atmosphere forms
1 Oct : Earliest known life on Earth
7 Oct : Earliest known fossils
18 Dec : First many-celled life forms
19 Dec : First fish
21 Dec : First land plants; first insects
23 Dec : First reptiles
24 Dec : First dinosaurs
26 Dec : First mammals
27 Dec : First birds
28 Dec : First flowering plants
28 Dec : Dinosaurs extinct
31 Dec (11:55 pm) : Homo sapiens (modern human) appears

HOUR:MINUTE:SECOND / Fractions of second

11:59.50.487 pm -- Great Pyramid is built (2520 BC)

11:59.55.333 pm -- Great Wall of China is built (215 BC)

11:59.56.785 pm -- Roman Empire falls (AD 476)
11:59.58.026 pm -- Battle of Hastings ( 1066)
11:59.58.921 pm -- Columbus lands in America (1492)
11:59.59.128 pm -- Shakespearewrites his first plays (1588-90)
11:59.59.874 pm -- World War II ends (1945)
11:59.59.891 pm -- Mount Everest is climbed (1953)
11:59.59.924 pm -- Man lands on the Moon (1969)
Midnight -- Today

THE WORLD IN A SINGLE DAY
In one day (24 hours or 3,600 minutes or 216,ooo seconds) the world turns once on its axis. During that time, on average :

• 358,522 people are born
• 155,012 people die
• 203,510 are added to the world's population

Taken from : Whitaker's World of Facts page 12

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