1.
The History of
Timekeeping
Karen Isabelle Soares
Karla Natalia Queiroz

2.
The History of Timekeeping - 2/13
Using the Sun
noon
sunsetsunrise

3.
The History of Timekeeping - 3/13
Sundial Clocks
 Oldest type of clock
 Also called sun clocks
 The shadow points to a number
 Depend on the sun

4.
The History of Timekeeping - 4/13
Water Clocks
 Around 4,000 B.C.
 Babylon, Egypt, India or China
 Water traveled through a tube
 Tell time during the night

5.
The History of Timekeeping - 5/13
Dividing the Year into Months
 12 Moon cycles in a year
 Greeks divided the year in 12 months

6.
The History of Timekeeping - 6/13
Dividing the Year into Days
 They divided the month in 30 days
 360 Days in a year
 360 Degrees in a circle
90°
180°
270°
360°

7.
The History of Timekeeping - 7/13
Dividing the Day into Hours
 Egyptians and Babylonians
 Sunrise to sunset in 12 hours, sunset to sunrise also in 12 hours
 Whole day in 24 hours
+

8.
The History of Timekeeping - 8/13
Minutes and Seconds
 Sumerian Sexagenary Sistem

9.
The History of Timekeeping - 9/13
Mechanical Clocks
 Invented in medieval
Europe
 Common in churches
and monasteries
 “Clock” is from the
Latin word “clocca”
 One time-keeping
hand

10.
The History of Timekeeping - 10/13
Spring-powered Clocks
 Around 1500
 Became very popular among the rich
 Was the precursor to accurate timekeeping

11.
The History of Timekeeping - 11/13
Pendulum Clocks
 Developed by Christian Huygens around 1656
 Pendulum clock had a minute hand
 Used to swing a lot (about 50 degrees)
 They stopped running after a while and had to be restarted

12.
The History of Timekeeping - 12/13
Quartz Crystal Clocks
 Based on an electric property of the quartz crystal
 When you apply voltage, or electricity, and pressure, the
quartz crystal vibrates or oscillates at a very constant
frequency.
 Very precise

13.
The History of Timekeeping - 13/13
Time Zones
 In 1884, delegates from 25 countries divided the world into
time zones.
 The delegates divided the 360 degrees of the Earth into 24
zones of 15 degrees each.
 In the United States, there are four time zones: Eastern,
Central, Mountain, and Pacific.