With financial support from Sanders and Hubbard, Bell hired Thomas Watson as his assistant,[N 15] and the two of them experimented with acoustic telegraphy. On <answer>June 2</answer>, 1875, Watson accidentally plucked one of the reeds and Bell, at the receiving end of the wire, heard the overtones of the reed; overtones that would be necessary for transmitting speech. That demonstrated to Bell that only one reed or armature was necessary, not multiple reeds. This led to the "gallows" sound-powered telephone, which could transmit indistinct, voice-like sounds, but not clear speech.
What month and day did Watson and Bell have a breakthrough?
June 2