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Puzzle
5 Answer
The first traffic light was installed
in London,
England in 1868, long before the invention of cars. It was used
to
prevent pedestrians from being trampled by the horses. The device
looked like railway signals. Semaphore arms were used in the
days,
but green and red lamps were used at night to represent "caution" and
"stop".
A policeman had to turn a lever to change the light. The first
automatic
traffic lights like those we are using were installed in the 1920's in
Detroit, Michigan, USA.
Source of information: Extraordinary
Stories
Behind the Invention of Ordinary Things* by
Don L. Wulffson
*This book is out of print. You
may look
for it in your local library. However, our bookstore is offering
a wide selection of interesting stories about inventions. Click
here to enter.
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