Abstract: This invention relates to a cannula for tracheal intubation, inserted through the hole made in the trachea of the patient. The cannula is fitted at the top with a mechanically operated valve which remains open during normal breathing but which can close and consequently interrupt the flow of air to the outside when the patient, in order to direct the air towards the vocal cords, breathes out with greater force, sufficient to overcome the resistance of the spring within the valve.

Abstract: A device for automatic advance of a rotating tool towards a workpiece, which includes a rotating tool holder for holding a cutting tool for operation on the workpiece. A gear wheel bears against the rotating tool holder which forces it toward the workpiece. A holder is provided to secure the gear wheel with respect to the workpiece. A device associated with the rotating tool holder engages the gear wheel and rotates it as the tool holder rotates. Associated with the holder and the gear wheel is a mechanism for advancing the gear wheel towards the workpiece as the gear wheel rotates. A stop motion apparatus associated with the gear wheel and the rotating tool holder is included for stopping the rotational movement of the gear wheel. The stop motion apparatus consists of a non-rotatable cam which operates on the cam follower to disengage it from the gear wheel, stopping the rotating movement thereof during a segment of the rotation of the tool holder.