TO PLAY ON TWO WHISTLES AT ONCE

Double a length of gutta percha tubing, say two yards long, and cut a slit in the centre, where you insert one end of another piece of tubing, of the same or a greater length.

In the two end openings put whistles, and make the whole air-tight. Place the free end of the long piece around the nozzle of a bellows, and on forcing the air from which into this novel instrument a double succession of sounds can be produced. The whistles should be pitched differently, and more than two can be used.