Rahul Khadse
Exclusive from (1001 Inventions That Changed the World) Book
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RHN
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Rahul
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Preface
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Trevor
Baylis
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General
editor
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Jack Challoner
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Patent processed at
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U.S.
Patent Office in Washington, DC
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Published
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By
Hachette India in 2013©
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Blog
No
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6
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Contain Type
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From
Rome To Revolution
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Invention
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Odometer
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Year
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(c.27
B.C.E.)
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Vitruvius makes measuring distances simpler
Measuring the distance between two
places is a basic task in cartography. The
earliest method was to walk and count the number of times a specific foot hit
the ground – a thousand right steps, for example, mode a mile ( from the Latin
mille, “meaning on thousand”).
The Roman architect and engineer, Vitruvius (C.75
B.C.E.), mechanized the process. Around 27 B.C.E he devised a wheelbarrow- row-
type device that dropped a pebble into a
container every time its large wheel of known circumference rotated once. At
first this was pushed along by hand, but it was soon incorporated into a chariot, the standard chariot
wheel being 4 feet (1.2M) in diameter. This wheel turned 400times in a Roman
mile. Needless to say, the smoothness of the road was important. The device was
described by Hero of Alexander in chapter thirty – four of his book
Dioptra.
Around 300 C.E the Chinese- Some sources suggest chang heng – devised a
similar, but more musical, instrument. Every time the road wheel of a special
coach rotated once, a pin moved a tooth on an internal cog
wheel. Every complete rotation of the cog wheel
activated a tick that banged a drum. Every tenth drum beat was replaced by a
sounding gong. Distance between towns could be easily measured in this way to accuracy
of tenth of a mile.
Early motor cars had odometers (or milometers) fitted to one of the road
wheels, these having separate gears that registered distance of 1,10,100,1000
miles, so on. Measured distance was a function of the tire pressure. Since
1980, cars have had odometers that indicate the number of miles traveled up to
999,999.
Simple hand – pushed odometers are still used today
by city surveyors, & these are sometimes called waywisers or perambulator.
Word Meanings-
- Cartography – The science or practice of drawing maps.
- Pebble – A small stone made smooth & round by the action of water or sand.
- Chariot – A two – wheeled vehicle drawn by horse, used in ancient warfare & racing.
- Cog – A wheel or bar with a series of projections on its edge, which transfers motion by engaging with projections on another wheel or bar.
Posted in: From Rome To Revolution
