| 摘要 |
The present invention relates to a measuring device, conversion device or ruler having specifically or universally selectable scales which can be used to measure distances with a desired linear or logarithmic scale, to draw distances to a desired scale, or to divide distances into a desired number of equal parts. The ruler comprises a transparent support plate having special graduations which are either composed of parallel, equally spaced lines or parallel logarithmically spaced straight lines, or composed of inclined angularly spaced lines. In the instance where the lines are angularly spaced, as in a ray-like structure, it may be composed of rays of inclined, straight or curved lines, said inclined lines or their extensions having a common intersection and the spacings between any two neighboring lines being equidistant, regularly increasing, or logarithmic-related distances in at least one direction. A specific scale may be selected by rotating the ruler to a certain degree of angle as is in the former cases or by moving it parallel to a certain position as in the later cases.
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