A pair of copper or brass hemispheres joined to form a hollow globe from which the air can be extracted to demonstrate the pressure of the atmosphere, which then prevents them from being pulled apart.Magdeburg hemispheres from the latter part of the nineteenth century and the early part of the twentieth century were rarely marked with the name of the maker....
n this demonstration 16 horses could not pull apart the two halves of an evacuated sphere, which became known as Magdeburg hemispheres.
Origin
Early 19th century: named after the city of Magdeburg, home of the inventor, Otto von Guericke (1602–86).