| 摘要 |
This invention relates to a novel design of a drafting instrument capable of assisting in the accurate drafting of arches, circles, as well as the measurement of angular relationships, and the like, whereby a base plate defines a circular opening having a cover plate symmetrically positioned about the perimeter of the opening formed in said base plate, there being symmetrically positioned about the center of the opening formed within the base plate a series of gear members such that upon the placement of a templet member whose dimensions are such as to have its perimeter come into mechanical contact with each of the gear members there is achieved a unique and novel means of positioning the templet member about the surface of a drawing while providing a mechanically accurate means to rotate said templet member about its center axis. By utilizing a templet having pre-conceived openings formed through its surface capable of receiving the point of a pencil or pen, there is achieved a means to accurately draw upon a surface arches, circles, and the like, as well as to achieve the measuring of angular relationships.
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