196. The automobile (or car)
People have been able to travel much more freely,
and across much greater distances, than was possible in the past.
The automobile, which most people refer to as the "car"
has also had some harmful consequences, such as pollution and accidents.
However, it is clear that life has changed profoundly as a result of the car.
Modern cars are very complicated, but the basic idea of how a car works can be described briefly.
When the keys are turned in the ignition of the car,
this creates a spark that ignites some gasoline vapor inside a cylinder.
Then, the rapid expansion of this vapor pushes against a part called a piston.
The movement of the piston then causes a turning motion in a shaft that is connected to the wheels.
The wheels turn, and the car moves.
The invention of the car, and the engines used by cars,
happened gradually in the late nineteenth century, mainly in France and Germany.
In the early twentieth century, an American engineer named Henry Ford developed a new way of making cars.
Instead of having one worker produce an entire car,
he had each worker perform one part of the production of many different cars.
This system was very efficient and allowed the mass production of cars.
The first car to be produced in large numbers was called the "Model T".
The Model T Ford and other cars that were soon produced in large numbers
were cheap enough that many people could afford to buy them.
Many new roads were built and paved throughout North America to allow cars to be driven from town to town.
People were able to travel much more easily and to visit places that had previously been difficult to reach.
Some problems also came with the widespread use of cars.
One of these problems was air pollution, because car engines burn gasoline,
which produces poisonous exhaust fumes.
Gradually, new laws and new technology have led to reductions in the air pollution that is caused by cars.
Moreover, cars today are much more "fuel efficient" than they were in the past,
requiring less gasoline to travel a given distance.
However, this pollution is still a problem because of the many millions of cars that are used each day.
Another problem has been car accidents, which have caused many thousands of deaths each year.
During the 1960s, some journalists brought attention to the unsafe features of many cars.
As a result, the safety of cars has been greatly improved.
In addition, the use of seat belts is now required by law.
However, car accidents continue to be a serious problem.
The future is likely to bring many interesting new changes to the car.
Improvements in the safety of cars, in fuel efficiency,
and in the cleanliness of car emissions are continuing to be made.
Also, the increasing use of the car in economically developing countries will probably have important effects upon people's lives around the world.