Abstract: A hollow, open-ended sheath is removed from a position enclosing a catheter which has been inserted through the sheath with a close tolerance and introduced into a human body thereby. A cutting blade is mounted in a deforming and guiding mechanism connected to the blade and engageable with the sheath for exerting pressure on the sheath in such a manner as to deform the sheath away from the catheter at a point immediately adjacent to the cutting blade and into contact with the cutting blade while maintaining the catheter beyond the reach of the blade. The device guides the blade for lengthwise movement relative to the sheath. The blade cuts the sheath in a lengthwise direction for removal from the catheter while the catheter remains in place.

Abstract: A telecommunications exchange having a multiple stage switching network. Calls initiated within the exchange may be local calls to be completed internally, may be trunk calls to a central office or may be enquiry calls completed locally. For calls of the last type, a tone stage in parallel with the first switching stage of the network is used. Resistors each having one half the resistance of the subscriber line input resistance are connected to each inlet wire from the subscriber to the tone stage. The tone stage is used in local calls for providing tone signals and also used for enquiry calls. For providing d.c. bias to the speech wires, a pad stage is provided in parallel with the second switching stage. Resistances in the leads to this stage provide attenuation.