Page 125 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Transport

How do parking

meters work?

Find out how these dreaded machines police our parking 24 hours a day

ince the first parking meter was
installed in Oklahoma in 1935, they have
Sspread throughout the world, as cars
became the dominant mode of transport. In
the UK alone, parking meters provide revenue
in the region of £500 million ($762 million)
each year, just from on-street parking.
For cash payments, the meter identifies
each inserted coin by conducting a set of
pre-programmed tests, which include
weighing the coin and testing its physical
properties using electrical currents or lasers.
This helps to distinguish between the
different types of metal that are used to
create the coins.
In America, the process is often simplified
by accepting only one type of coin, most
commonly the quarter. Parking meters in the
US commonly only monitor one space;
modern versions do this with the help of
special sensors that use lasers to determine
when the space has been vacated. Once it is
vacated the clock is automatically reset to
zero, so that another car can’t use someone
else’s parking time for free. Individual
More and more parking
parking meters are largely being replaced by meters are now accepting
modern pay-and-display meters, as they take electronic payments, and © Science Photo Library
up less space and can be powered by solar some even use pre-loaded
smart cards
energy.

How is crop dusting

conducted?

Million-dollar planes keep our farms pest- and weed-free

uzzing over farmland between 30 and 100 landing strip, so pilots are required to have at least
times a day, crop dusting or ‘aerial 250 hours of flight experience before taking to the
Bapplication’ has been an effective way to skies in one of these planes. © Mikael Buck/Rex Features; LuckyBusiness/Dreamstime; Thinkstock
tend to crops since the early-20th century. The practice eliminates the risk of damage by
Originally balloons and biplanes were used, but in heavy tractor wheels and does not cause soil
2015, planes have intricate GPS systems and compaction, which can affect the yield. There is a
application methods designed to spread pesticides growing fear that insects are getting wise to the
Crop dusting is now a specialised evenly. The aircraft can also be used as water chemicals and are hiding further down the plants,
profession that requires a
commercial pilot’s licence bombers to put out forest fires and are particularly so crop dusting is now done at night to catch the
effective against locust hordes. Often there is no little critters off-guard.

How It Works 125