General service whistle (City Police or Fire Brigade)

This instrument is part of the Hassall collection. It is a two-note, tube-shaped, chrome- or nickel-plated whistle with a waisted tubular mouthpiece, two aligned opposite windows, and a cap with post and ring for a lanyard. The tube has a brass partition (slab) inside, which divides it in two sound chambers, thus creating two dissonant notes.