Stephen Ptacek

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Gutzon Borglum. Presidents. Sculpture. National park. George Washington. Thomas Jefferson. Theodore Roosevelt. Abraham Lincoln. Mount Rushmore National Memorial, South Dakota.

9 Memorials and Monuments in the United States

Drinking water is poured into a glass.

Water Fluoridation: Just the Facts

Aurochs. Bos primigenius. Skeleton. Extinct animal. Skeleton of an Aurochs, an extinct wild ox.

6 Animals We Ate Into Extinction

Figure 13: A Maxim machine gun, belt-fed and water-cooled, operated by German infantrymen, World War I.

7 Deadliest Weapons in History

Berries and leaves of the bittersweet nightshade (Solanum dulcamara) plant. Poisonous plant

7 of the World’s Deadliest Plants

Internet http://www blue screen. Hompepage blog 2009, history and society, media news television, crowd opinion protest, In the News 2009, breaking news

Who Invented the Internet?

Illustration for Demystified "How Dangerous is Quicksand"

How Deadly Is Quicksand?

Stephen Ptacek

American pilot

Learn about this topic in these articles:

association with MacCready

In Paul Beattie MacCready
The pilot was Stephen Ptacek, weighing 122 pounds (55 kg). The plane, powered by 16,128 solar cells connected to two electric motors, weighed 210 pounds (95 kg) and had a wingspan of 47 feet (14.3 m).
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