Magdeburg hemispheres
Date1800-1820
Inventory Number1998-1-1223a,b
ClassificationMagdeburg Hemispheres
Subject
Attributed to
W. & S. Jones
fl. 1791 - 1859
Cultural Region
Place of Origin
Dimensions30.5 x 11.5 x 11.5 cm (12 x 4 1/2 x 4 1/2 in.)
hemispheres diam.: 11.5 cm (4 1/2 in.)
hemispheres diam.: 11.5 cm (4 1/2 in.)
Material
DescriptionThis pair of Magdeburg hemispheres is made in brass, with molded rims mounted on a hollow shaft fitted with a stopcock. The handle below the stopcock is removable so this hemisphere can be fixed to an air pump.
In Collection(s)
Signedunsigned
Curatorial RemarksThis set of Magdeburg hemispheres fit the W. & S. Jones air pump (#0021) in the collection. Though it could only be a coincidence, it is fair to assume that it probably came with this instrument, whether at the same time or a later period.
FunctionMagdeburg hemispheres are used to demonstrate the strength of the atmosphere's air pressure. Once air has been removed from inside the two hemispheres, it become extremely difficult to separate them (handles were provided on the hemispheres to try this experiment). Otto von Guericke illustrated this point with a horse carriage on each side of the tiny hemispheres. When there is no air pressure from inside, the normal air pressure from the surrounding atmosphere pushes on the hemispheres, forcing them together.
A video demonstration of a set of Magdeburg spheres by the Fondazione Scienza e Tecnica in Florence is available on Youtube here.
A video demonstration of a set of Magdeburg spheres by the Fondazione Scienza e Tecnica in Florence is available on Youtube here.
James Ferguson
Date: circa 1760
Accessories: case
Object number: 1998-1-1416
See also/See also
