OBJECT OF THE MONTH
Campbell-Stokes Recorder
This object is described as an "Equinoctial" in the museum register and the cards that come with it have "equinoctial cards" printed on them. When I did a little online research to find out what it's function was, the word equinoctial is defined as
"relating to an equinox or to a state or the time of equal day and night" - this was not very helpful and didn't tell me what it did. After a bit more research I found out it is called the Campbell–Stokes recorder (sometimes called a Stokes sphere) and is a type of sunshine recorder. It was invented by the Scottish author and scholar John Francis Campbell in 1853 and modified in 1879 by Sir George Gabriel Stokes. The original design by Campbell consisted of a glass sphere set into a wooden bowl with the sun burning a trace on the bowl. Stokes's refinement was to make the housing out of metal and to have a card holder set behind the sphere. The unit is designed to record the hours of bright sunshine by burning a hole through the card.
It is still used today throughout the world, its advantage being that it has no moving parts, does not require a power source to operate and needs minimal maintenance.
Read more -
"relating to an equinox or to a state or the time of equal day and night" - this was not very helpful and didn't tell me what it did. After a bit more research I found out it is called the Campbell–Stokes recorder (sometimes called a Stokes sphere) and is a type of sunshine recorder. It was invented by the Scottish author and scholar John Francis Campbell in 1853 and modified in 1879 by Sir George Gabriel Stokes. The original design by Campbell consisted of a glass sphere set into a wooden bowl with the sun burning a trace on the bowl. Stokes's refinement was to make the housing out of metal and to have a card holder set behind the sphere. The unit is designed to record the hours of bright sunshine by burning a hole through the card.
It is still used today throughout the world, its advantage being that it has no moving parts, does not require a power source to operate and needs minimal maintenance.
Read more -