Abstract: The present invention makes possible the quick, accurate analysis of images, especially medical diagnostic images of unknown magnification, to determine the size of objects visible therein, by reference to an object of known size or to determine the magnification ratio when it is unknown. There is provided a transparent image measuring device having one or more line pairs of varying spacing. Various scale markers are included on lines running substantially at right angles to the line pairs. The device is placed on the image over an object of known size (the reference object). The device is located so that the reference object just bridges between the spaced-apart lines in a particular location which is associated with a scale marker corresponding to the true size of the reference object.

Abstract: Method and apparatus for interpolating elevation values and related locations from data provided on drawings by using an instrument with a supporting scale bar on which are mounted two slides that each has an extension arm. In use, the slides are set at the elevation values of the points on the drawing and one of the slides is moved along the scale bar intersecting a graphic scale at various intervals. The movable arm on the slide intersects the line joining the points on the drawing at various intervals.

Abstract: A planar member 21, is pivotally assembled to a transparent planar member 22, at pivot point 23. On the planar member 21, are the calibrated circle 24, the cosine/secant scale 25, and the sine/cosecant scale 26.On the transparent member 22, are the sine/cosine cursor circle 27, the tangent/cotangent scale 28, and the arrow head 29.For any relative position of the two members, the arrow head 29, points to an angle. Each of the six trigonometric functions of that angle is read where the appropriate scale is intersected by another line.FIG. 2, shows the device set at 150 degrees as an example. The sine and the cosine of 150 degrees are read at intersections 33 and 34 respectively. The secant and the tangent at intersection 31. The cosecant and cotangent at 32. The sign of any cotangent reading needs to be reversed.

Abstract: A computational aid device for Ekelund range determinations comprising a e member adapted to be placed over a bearing/time plot and including two leg members to be aligned with intersecting bearing rate lines faired through the plot, and a range scale positionable with respect to the base and the leg members to provide direct readings of range and of probable limits of range error.

Abstract: A calculator for facilitating the layout of parking lot stalls of desired length and width at a desired angle. The calculator includes a first member having orthogonal length and width scales as well as angle indicators relating to desired stall angle. A second member is pivotable on the first, and includes indicia related to desired stall length and width. The second member is positioned for pivoting on the first, is aligned according to the desired stall data to provide a direct readout of the orthogonal length and width dimensions necessary to lay out the stalls.

Abstract: A slide rule cursor which is adapted for use with conventional slide rules to provide direct resolution of the resultant value of parallel and/or series impedances. The cursor is not only movable axially along the body of the slide rule in a conventional manner but is also movable perpendicularly to the axial direction of the body of the slide rule. The cursor has printed on it a series of curves from which unique values of a special coefficient referred to as .mu..sub..theta. may be readily obtained for each network of parallel and/or series impedances. This value of .mu..sub..theta. relates the individual impedances in the network through a series of relationships discovered by the inventor to the resultant value of impedance and its angle.

Abstract: A course correction calculator for use in light aircraft includes two arms pivotally connected together and each independently pivoted over a map supported on a base. The pivot connecting the two arms is slidable longitudinally along one of the arms and the other of the arms is slidable longitudinally relative to one of two pivot points. A protractor is provided at the pivot connecting the two arms to indicate the angle between them and hence course correction when the two independent pivots are at the departure and destination points on the map and the mutual pivot is at the aircraft's position on the map.