Apparatus, known as a guinea and feather apparatus

This apparatus, known as the 'guinea and feather apparatus', was made in England in the late 19th century. It was used to demonstrate the effects of a vacuum. It is unsigned.

The glass cylinder was placed on an air pump (not shown) and evacuated. The brass cap at the top contains a release mechanism for a guinea (a gold coin worth one pound and one shilling) and a feather which would drop simultaneously and, because of the lack of air resistance, hit the bottom together.

The existence of a vacuum had been controversial since ancient times, until the invention of the barometer in Italy in the 17th century conclusively proved it. This led to great interest in how material (and living creatures) reacted in conditions of increased or decreased atmospheric pressure. This experiment is as old as the air pump itself, dating from the late 17th century.

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