Patent ID: 7080459

Claim:
A drafting instrument comprising: a main ruler body, said main ruler body having two plate shaped elongated arms joined on one side and extending outward and parallel on the other side, said arms defining a slot between and along the length of the said arms, one of said arms having an extrusion with a pointed end extending from said one arm, the other said arm having a quarter circle plate extending oppositely from said extrusion, said quarter circle plate having measurement indicia along a periphery indicating angles from 0 to 90 degrees to provide protractor function; a slide ruler dimensioned to fit inside the slot and to slide freely along the two arms, said slide ruler having a place ring with an aperture that defines a means holding a writing tool, said aperture and said means being aligned with said extrusion having said pointed end to provide compass functions as the instrument is rotated about the pointed end, said slide ruler further including a stem extending outwardly opposite from said extrusion of said main ruler body and in alignment with said quarter circle plate of said main ruler body; the stem having a pin hole at the top end and the quarter circle plate having a pin hole at an outward end wherein a thread is inserted through said pin hole of said quarter circle plate and tied to said pin hole of said stem, and wherein said pin holes form foci for an ellipse and said thread is a means for drawing said ellipse.