A timepiece barrel includes a drum defining a first compartment and a superimposed second compartment; a first tubular hub secured to a first cover and housed at least partially in the first compartment; a second tubular hub secured to a second cover housed at least partially in the second compartment. Each compartment contains a spring wound into a spiral and an inner first end of which collaborates with the first and second hubs respectively and a second end of which collaborates with the drum. The compartments are open on the side of the covers and the first and second covers are free with reference to the drum and are each provided with peripheral teeth, while the drum has no teeth.