Mariners began to use barometers in the 18th century to predict changes in the weather, but it was in the 19th century that their use at sea became widespread. This marine cistern barometer has a mahogany case and brass gimbals that allow it to remain level when used on a ship at sea. The brass scale is marked in inches of mercury (26.5" to 31") and has a vernier that allows accurate reading of the scale to one hundredths of an inch. Both the glass tube and the boxwood cistern are later replacements. Lower half of the cistern case has been removed.

According to a handwritten note with the barometer, it was bought from the effects of Dr Lettforn of Mile End Road, Bow, in east London, who had purchaed it at the sale of the effects of Captain James Cook's widow.