Everything about The Magdeburg Hemispheres totally explained
The
Magdeburg hemispheres were a pair of large copper hemispheres with mating rims. When the rims were sealed with grease and the air was pumped out, the sphere contained a
vacuum and couldn't be pulled apart by teams of horses. The Magdeburg hemispheres were designed by German scientist
Otto von Guericke in 1650 to demonstrate the air pump he'd invented and the concept of air pressure. The first artificial vacuum had been produced a few years earlier by
Evangelista Torricelli, and had inspired von Guericke to design the world's first
vacuum pump, which consisted of a piston and cylinder with one-way flap valves. To power the machine, several people would turn a crank arm connected to the vacuum pump.
Overview
The Magdeburg hemispheres, a little over a foot (30 cm) in diameter, were designed to demonstrate the
vacuum pump that von Guericke had invented. When the air was sucked out from inside them, they were held firmly together by the
air pressure of the surrounding
atmosphere.
Demonstrations
Guericke's demonstration was presented on
8 May 1654 to the
Reichstag and the
Emperor Ferdinand III in
1654 in
Regensburg, where 30 horses, in two teams of 15, couldn't separate the hemispheres until the vacuum was released. In
1656 he repeated the demonstration with 16 horses (2 teams of 8) in his hometown of
Magdeburg, where he was mayor. In
1657,
Gaspar Schott was the first to describe the experiment in print in his
Mechanica Hydraulico-Pneumatica. In
1663 (or according to some sources in
1661) the demonstration was given in
Berlin before
Frederick William, Elector of Brandenburg) with 24 horses.
The original hemispheres are maintained by the
Deutsches Museum in
Munich. Many copies of them (usually smaller) have been made to illustrate the principle of
air pressure to students. Re-enactments of von Guerike's 1654 experiment are performed in locations around the world by the
Otto von Guericke Society. The experiment has been commemorated on at least two German stamps.
Related
After learning about Guericke's pump through Schott's book,
Robert Boyle worked with
Robert Hooke to design and build an improved air pump. From this, through various experiments, they formulated what is called
Boyle's law, which states that the volume of a body of an ideal gas is inversely proportional to its pressure. Soon the
ideal gas law was formulated.
Based on these concepts, in
1679, an associate of Boyle's named
Denis Papin built a
bone digester, which is a closed vessel with a tightly fitting lid that confines steam until a high pressure is generated. Later designs implemented a steam release valve to keep the machine from exploding. By watching the valve rhythmically move up and down, Papin conceived of the idea of a piston and cylinder engine. He did not, however, follow through with his design. Nevertheless, in
1697, based on Papin's designs, engineer
Thomas Savery built the first commercial
steam engine.
Trivia
A variation of Schott's sketch featuring a single pair of horses trying to separate a pair of
jeans appears on the tag of
Levi Strauss & Co. jeans.
Further Information
Get more info on 'Magdeburg Hemispheres'.
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