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Transcript of Clock Presentation
How the measurement of time has evolved over the years.
By Hannah and Malia
The measurement of time dates back millenniums ago. It is not known who first invented a device to measure time, but we do know what it was. The sundial started it all; and now the atomic clock. Clocks are similar to calendars, but also very different. They measure time while calendars on the other hand measure the days, months, etc. These instruments have changed dramatically over the years; what caused them to evolve and what was needed to make these improvements?
Who Invented These Clocks and When
Sundial (3500 BC): Theodosius of Bithynia (modified)
Candle Clock (1400 BC): not known
Hourglass (300 BC): Liutprand
Astrolabe (225 BC): Hipparchus
Clepsydras (Water Clock) (1092 AD) the Greeks
Mechanical/Pendulum Clock (1656): Christian Huygens
Quartz Clock (1927): Warren Marrison and J.W. Horton
Atomic Clock (1949): US NIST (National Institution of
Standards and Technology)
It is not known who invented the first sundial, however it is known that Theodosius of Bithynia modified the sundial so it could be used anywhere on Earth. A basic sundial works by casting a shadow onto the dial face. It's position is determined by the sun's location in the sky; this changes with the time of the day. Marks on the dial face are used to tell what time it is, based on the shadow casted by the gnomon (the rod in the center of the sundial).
Sundials were used around the whole world at one point in time. More precise sundials were built in Egypt. It consisted of a straight base with a raised crosspiece at one end. Only 64 years after obtaining it's first sundial, The Tower of the Winds was constructed in Athens. It is octagonal in shape and contained eight sundials. Sundials facing various cardinal compass points were in use at least since then. This improvement helped make sundials more accurate, leading to other clocks down the road more accurate as well.
The first hourglasses are credited to the Greeks and date back to 300 BC. However, it wasn't until eighth century that these timekeeping devices first appeared in Europe. The first one in this continent may have been made by Luitprand, a monk from France. During the Renaissance, many households and buildings had an hourglass to be used for everyday things such as cooking, regulating working hours, and other activities.
Hourglasses have three main parts: the glass, the frame, and the sand. The glass is simply blown glass, and the frame can be made out of wood, various metals, bamboo, and other materials that allow the craftsman to carve the frame to whatever shape he desires. The sand, however, is the trickiest part, since it has to flow smoothly and not get caught in the small crevice between the two glass spheres. Round sand grains, and rock dust and rock flour, are the best kinds of sand for hourglasses. Miniscule glass beads are actually the most functional 'sand' because their round edges flow smoothly through the glass. In addition, they can be made in different colors so the sand in the hourglass can be chosen to match color preference.
~Cummings, Floyd Ernie. "History of Clocks." Clock a History - Timekeepers. Floyd Ernie Cummings, 1997. Web. 15 May 2013.
~Dwyer, Douglas. "How Stuff Works-Clocks." HowStuffWorks.com. HowStuffWorks, Inc, n.d. Web. 21 May 2013.
~Miller, Howard. "History of Clocks Timeline." History of Clocks Timeline. Howard Miller, 2004. Web. 15 May 2013.
~Invention Ware. "Inventions and Inventors." Inventions and Inventors. Inventionware.com, 2013. Web. 06 June 2013.
~Master, Web. "Early Clocks." NIST: A Walk Through Time. The National Institute of Standards and Technology, 5 Oct. 2010. Web. 14 May 2013.
~Types of Clocks." Time for Time. N.p., 2003. Web. 27 May 2013. *
~KryssTal. "Inventions: Years 1000-1500." www.krysstal.com. N.p., 2013. Web. 14 May 5. *
A clepsydra was an ancient time keeping device that measured time by marking the regulated flow of water through a small opening. It was simalar to a hourglass in the way that it functioned. One form, used by the North American Indians and some Africans, consisted of a small boat that directed water through a hole until it sank. In another form, the boat was filled with water that escaped through a hole, and the time was read from lines on the inside, measuring the level of the remaining water.
It may have been an invention of the Chaldeans of ancient Babylonia; specimens from Egypt date from the 14th century BC. The Romans invented a clepsydra consisting of a cylinder into which water dripped from a holding area; a floating figurine showed readings on a scale on the cylinder's wall. Clepsydras were used for many purposes, including timing the speeches of public speakers. As late as the 16th century, Galileo used a mercury clepsydra to time his experimental falling bodies.
A candle clock is a thin candle with evenly spaced markings, that when burned, indicate the passage of periods of time. While no longer used today, candle clocks provided an effective way to tell time indoors, at night, or on a cloudy day. A candle clock could be easily transformed into a timer by sticking a heavy nail into the candle at the mark indicating the desired interval. When the wax surrounding the nail melts, the nail falls onto a plate below creating a loud noise.
This type of clock was first used in the 13th Century. Not much more is known about who invented it, and where.
An astrolabe is like an elaborate inclinometer, and was normally used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time. It was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and Renaissance for all these purposes. In the Islamic world, it was also used to calculate the Qibla and to find the times for prayers.
There is often confusion between the astrolabe and the mariner's astrolabe. While the astrolabe could be useful for determining latitude on land, it would not have worked to heave on the deck of a ship or in wind. The mariner's astrolabe was developed to address these issues.
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping component. The advantage of a pendulum for timekeeping is that it is a harmonic oscillator; meaning it swings back and forth in a constant and precise time interval dependent on its length. Gears on the inside help count the seconds, minutes, and hours.
From its invention in 1656 by Christiaan Huygens until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. Pendulum clocks must be stationary to operate; any motion or accelerations will affect the motion of the pendulum, causing inaccuracies, so other types of clocks have to be used on the go. They are now kept mostly for their decorative and antique value.
Inside a quartz clock or watch, the battery sends electricity to the quartz crystal through an electronic circuit. The quartz crystal vibrates back and forth at a precise frequency: exactly 32768 times each second. The circuit "counts" the number of vibrations and uses them to generate accurate electric pulses, one per second. These pulses can either power an LCD display (showing the time numerically) or they can drive a small electric motor turning gear wheels that spin the clock's second, minute, and hour hands.
Quartz clocks are the most commonly used clock around the world. They are very accurate and never lose more than a second a day due to pressure or heat changes.
An atomic clock is a clock device that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element. Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, to control the wave frequency of television broadcasts, and in global navigation satellite systems such as GPS.
The principle of operation of an atomic clock is not based on nuclear physics, but rather on atomic physics and using the microwave signal that electrons in atoms emit when they change energy levels. Early atomic clocks were based on masers at room temperature. Currently, the most accurate atomic clocks first cool the atoms to near absolute zero temperature by slowing them with lasers and probing them in atomic fountains in a microwave-filled cavity. An example of this is the NIST-F1 atomic clock, the U.S. national primary time and frequency standard.
*not all information needed to create proper citation was given.
Over the 3 time periods (before, during, and after the renaissance) they way time was measured has changed dramatically.
-Before the Renaissance: Everything was estimated and used water, sand, or the sun to measure time amounts or the time of day. Wood was used as a main frame for hourglasses. Nothing was accurate or consistent.
-During the Renaissance: The pendulum, or mechanical clock was invented. It was the most accurate clock of it's time and still used wood as a frame. Metal, small screws and gears were introduced.
-After the Renaissance: Clocks are exceptionally accurate and time measurement is the same all around the world. Clocks can be worn on your wrist!!! Portable time measurement...
These changes to clocks of all sorts were made by scientists, mathematicians and inventors because the need for a more accurate way to keep time was crucial. More knowledge, tools, and resources were needed to make these improvements to clocks.