Abstract: A luminous spot in a model area displays the position and movements of an object in space by means of apparatus which receives a location signal, such as a radar signal, indicative of the instantaneous coordinates of the object with respect to each of three axes of a system of coordinates in the space. The apparatus includes an oscilloscope and a thin, converging lens which is rotated about an axis parallel to the screen of the oscilloscope and perpendicular to the optical axis of the lens. A potentiometer coupled to the lens generates an angle signal indicative of the instantaneous angle defined by the optical axis and a line perpendicular to the oscilloscope screen. Control circuits connected to the source of the location signal cooperate with the oscilloscope to produce a visible, luminous signal in a point of the screen surface when the afore-mentioned instantaneous angle assumes a predetermined value.

Abstract: Better coffee is made in a conventional percolator when the percolator is heated on a metal heating plate having a planar top surface and a locating recess centered in the surface. A small metal spacer having two oppositely directed, substantially planer and parallel faces is provided with a fixed locating projection on one of its faces. The dimensions of the projection permit it to be slidably received in the locating recess of the plate so that the bottom face of the spacer makes heat-transmitting area contact with the surface of the plate. When a water-filled percolator is placed on the top surface of the heating plate in the absence of the spacer, the water may be quickly heated almost to a boil. When the spacer then is inserted and the percolator centered on the top face of the spacer, direct heating of the water in the percolator is limited to water in the pumping assembly of the percolator during coffee brewing.