A musical instrument operating one of Helmholtz's artificial larynxes.
A siren worked by explosion of small quantities of oxygen and hydrogen mixed.
Three other sirens made to give vocal sounds or articulate speech.
A device for projecting sound-waves to a distance without spreading and in a straight line, on the principle of smoke rings.
A device for continuously indicating on a galvanometer the depths of the ocean.
A method of preventing in a great measure friction of water against the hull of a ship and incidentally preventing fouling by barnacles.
A telephone receiver whereby the vibrations of the diaphragm are considerably amplified.
Two methods of "space" telegraphy at sea.
An improved and extended string telephone.
Devices and method of talking through water for considerable distances.