This is really two write-ups for the price of one. While researching "The Magdeburg Experiment", I happened upon references to "The Magdeburg Experiment" which, as evidenced by the name, is completely different and totally unrelated (although both involve hollow spheres... coincidence?). Since I found both experiments to be most interesting, I've written them both up, delimited by a horizontal line. Sorry.

The Magdeburg Experiment.

This was a 17th century experiment conducted by Otto Von Guericke (1602-1686) in Magdeburg, Germany. In 1654 Von Guericke had designed a vacuum pump to withdraw air from vessels, and in 1657, based on his belief that air presses down upon us in an unseen force, he demonstrated in front of Ferdinand III and others, the tremendous weight of air.

In 1656, Von Guericke was intrigued by a question. If one placed two hemispheres together, and removed all the air from them, what force would be needed to pull them apart? Could one person do it with a hand on each side? Two people? Two strong people?

Otto calculated that it would take several horses, pulling with all their might, to break apart a 62cm diameter globe, with a force of 32940 Newtons. His contemporaries did some calculations of their own, and found his conclusions a little hard to swallow. So he decided to prove it.

Von Guericke used his pump to evacuate two very large, heavy hemispheres, after having placed them together with a leather seal, made airtight with grease or wax. The hemispheres were sucked together under the pressure of air outside, and using an increasing number of horses, Von Guericke then proceeded to try and pull them apart. It took more than 16 horses to split the spheres again. It was experiments such as these that encouraged early scientists to study air pressure changes.

The Magdeburg Experiment.

The Magdeburg Experiment marked the first ever commercial rocket venture. In the 1930s the City Council of Magdeburg, Germany believed that the Earth extended to infinity in all directions, and that it's inner surface was a hollow sphere with the sun at the centre, rather like a Dyson Sphere. This was based on the Hohlweltlehr or "Hollow World Doctrine" of one Peter Bender. Bender was an anti-intellectual Nazi Party member, who taught that Copernican heliocentric cosmology was a lie. He convinced the council of Magdeburg that they could prove their theory, if only they could launch a rocket high enough to pass the sun and land in Australia, on the opposite side of the sphere. To this end, they offered funds to the German Society for Space Research, who quietly thought the theory quite ludicrous, but were delighted to have financial backing to build really big rockets. A series of sub-scale test shots was completed successfully, but only after a spate of disasters that shook the confidence of the prospective pilots. A prototype man-carrying rocket was completed in 1934, but it promptly crashed and exploded, leaving the theory unproven.

In fact, what Bender and the council failed to realise was that no rocket flies "straight." Any sufficiently powerful rocket would be able to reach the antipodes after a curving, sub-orbital, ballistic flight, so the demonstration would prove nothing.

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