Abstract: A manifold for a bank of four cylinders of an engine comprises four primary tracts each leading to a respective cylinder, and two secondary tracts each connected at a respective one of two branching points to a respective pair of primary tracts which lead to cylinders of which the combustion cycles are in antiphase. The two branching points are arranged contiguous to one another to form a decoupling chamber between which there is disposed a valve connecting the two branching points. The resonant frequency of the manifold can be changed by opening and closing the valve.

Abstract: An extension cord apparatus is disclosed herein having a length of electrical cord with a plug attached at one end and plurality of electrical sockets attached at the oposite end. The length of cord is trained about the body or core of a reel rotatably mounted on a supporting frame. The sockets or receptacles are carried in a box mounted on the end of a spindle forming a part of the reel and a cover is pivotally attached to the box constituting a handle when extended outwardly from the box for the purpose of winding the length of cord onto the reel from its extended position. A guide and strain relief for the cord is carried on the frame as well as a handle for transporting the apparatus from place to place.