Oyster Dredgers at Porlock Weir is the only known work by the artist depicting a location in Somerset and was acquired by the museum for £28,000.
The 3ft x 5ft 8in (92cm x 1.73cm) oil on canvas from 1890 was sold by private vendors after the museum which is housed in Taunton Castle received a £12,000 grant from The Art Fund.
If the painting's setting was unusual, its subject was typical for a work by Hemy, a Newcastle-born painter who settled in Falmouth, Cornwall and was a specialist in coastal art. It showed sloops with oyster nets sailing close to the shore with main sloop's number, BR69, also visible and indicating that the boat was registered in Bridgwater in Somerset.
At the time the picture was painted, Oyster dredging was still an important industry at Porlock Weir and, as such, the work was deemed to represent an important record of working life in Somerset. Oyster fishing in the area dates back to the 18th century but ceased in the early 1900s after boats from Whitby reputedly decimated the oyster beds.
The acquisition of the painting comes at a timely moment as new oyster beds were established in Porlock Weir last year, and their harvest and trade is scheduled to re-commence in 2016 as part of a community food-based project.
Stephen Deuchar, director of the Art Fund, said: "The painting addresses a historically-important local industry in Somerset, little represented in the visual art collections of the museum, but currently in revival. So we're very pleased to support the acquisition of this attractive and significant work by an artist of national repute."
Oyster Dredgers at Porlock Weir is now in Somerset Museum's permanent collection alongside other exhibits that explore the county's history.
The purchase follows another work by Hemy entering a public collection in April last year when Hauling in the Nets was bought by the Falmouth Art Gallery at Bonhams for £38,000 (plus premium).
Another gallery making a recent acquisition was the Mercer Art Gallery in Harrogate, North Yorkshire which bought a William Powell Frith (1819-1909) portrait at Christie's.
Offered at the King Street saleroom on June 16, the 11 x 13½in (28 x 34cm) oil on panel depicted the artist's wife aged 23 years old (the artist himself was three years older).
It was estimated at £7000-10,000 and was knocked down to the gallery at £16,000.
Frith was born near Harrogate and maintained strong connections to the area. This picture Isabelle Frith Reading was an intimate portrait from 1845, the year the couple married in York. It was painted during their honeymoon in the Derbyshire Dales.
Together, they had 12 children, however, nine years after this romantic getaway, Frith began an affair with Mary Alford who he later married in 1881, 12 months after Isabelle's death. Mary went on to bear him six more children.
With the acquisition made possible through funds from Art Fund Stephen Deuchar said: "It is great news that the Mercer Art Gallery was successful at the auction. This engaging portrait by Frith of his wife will make a fine addition to the gallery's collection of works by the artist, and also complement their wider 19th-century British holdings."
The Mercer Art Gallery already holds a substantial collection of Frith's works including the painting Many Happy Returns of the Day which depicts a family celebration for which Isabelle modelled.