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- [Narrator] Behold, the internal combustion engine.

But where did it come from?

Meet Nikolaus Otto, born in Germany in 1832.

Nikolaus wasn't the star of his high school.

In fact, he dropped out at the age of 16

and worked in a series of different industries.

When he was a traveling salesman,

Nikolaus caught wind of a coal-gas engine

invented by the French Étienne Lenoir.

Although it was was the first working

internal combustion engine,

Lenoir's design had a lot of problems.

First of all, gas was expensive at the time.

Second, the engine was relatively inefficient

and required a lot of water for cooling purposes.

Yet, Nikolaus saw potential in the concept.

First, Nikolaus built a two-stroke engine

that ran on liquid gas and used a carburetor.

In 1876, Nikolaus went on to build a four-stroke engine.

Here's how it works:

First, the engine mixes fuel with air in the intake phase.

Second, it compresses the mixture

and then combusts it with a spark.

The engine expels exhaust in the last stage.

Through this four-stage cycle,

the engine uses a series of small explosions

to convert fuel into energy.

These designs have become the basis

for most other internal combustion engines,

and within 10 years of its invention,

over 30,000 of the engines were sold.

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