This Canary Resuscitator was manufactured in the 1920s by Siebe Gorman and Co.; it was carried by miners to revive the canaries that were used from the late 19th century until 1987(!) as early-warning signals for potentially lethal gas leaks.
In Britain, most mines and all Mine Rescue Centres bred their own canaries. The birds were popular with miners, and they were often treated as pets. Following the introduction of electronic gas detectors in 1987, British mines phased out the use of canaries.
Rebecca's Object of the Week [National Mining Museum]