Joseph Wright sketch on show at Tate Britain

http://www.bbc.co.uk/news/uk-england-derbyshire-35923483

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The only known sketch of a seminal painting by Joseph Wright is on display alongside the finished version for the first time.

The rarely-seen sketch is a precursor to An Experiment on a Bird in the Air Pump, and is on the reverse of a self-portrait of the artist.

It has been loaned to Tate Britain as part of a display of Wright's work.

The paintings show a white cockatoo being deprived of oxygen as the formation of a vacuum is demonstrated.

Tate Britain curator Greg Sullivan said: "Having an opportunity to compare the early sketch with the final version will give us some insight into his original ideas about the work and what decisions he made to get to the final painting."

In the finished work, Wright depicts the demonstrator with his hand poised over the valve of the air pump, leaving it unclear whether the bird will die or be saved at the last minute.

However, the newly-displayed sketch shows that Wright originally planned to show the demonstrator holding his hand out to comfort a small girl, presumably offering reassurance that the bird would not die.

Joseph Wright 1734-1797

Source: BBC Your Paintings

Derby Museum curator Lucy Bamford, who is in charge of a collection of Wright paintings, said it was rare to find an oil sketch of his work.

The sketch shows how Wright decided to "ramp up the drama" in the final version, she said.

The final version of the painting was donated to the nation in 1863 and usually hangs in the National Gallery.

It was painted in 1768 and is Wright's most renowned painting.