Perspective drafting instrument

Claim 1

A DRAFTING MACHINE COMPRISING A DRAFTING TABLE, A FIRST FLAT STRIP CARRYING A FIRST DATUM LINE, A FIRST GRADUATED SCALE PROJECTING FROM SAID FIRSTT FLAT STRIP AND CARRYING A SECOND DATUM LINE, GUIDING MEANS PIVOTALLY MOUNTED ABOUT A FIRST PIVOT FIXED IN RELATION TO SAID TABLE, MEANS FOR SLIDABLY MOUNTING SAID FIRST FLAT STRIP IN SAID GUIDING MEANS, SAID FIRST FLAT STRIP THUS CONSTITUTING A FIRST SLIDE, A SECOND FLAT STRIP CARRYING A SECOND GRADUATED SCALE AND A THIRD DATUM LINE, A FIRST CURSOR MEMBER CARRYING SAID SECOND FLAT STRIP, MEANS FOR SLIDABLY MOUNTING SAID FIRST CURSOR MEMBER ON SAID FIRST FLAT STRIP FOR MOVING SAID THIRD DATUM LINE IN TO SAID SECOND DATUM LINE WHILE MAINTAINING SAID THIRD DATUM LINE PARALLEL TO SAID SECOND DATUM LINE, A THIRD FLAT STRIP CARRYING A FOURTH DATUM LINE AND PIVOTALLY MOUNTED ON A SECOND PIVOT LOCATED COAXIALLY WITH SAID FIRST PIVOT, SAID FOURTH DATUM LINE ALWAYS PASSING THROUGH THE COMMON AXIS OF SAID FIRST AND SECOND PIVOTS, SAID COMMON AXIS AND THE ZERO POINTS OF SAID FIRST AND SECOND GRADUATED SCALES BEING ALWAYS ALIGNED, A SECOND SLIDE SECURED TO SAID TABLE, A SECOND CURSOR CARRIED BY SAID SECOND SLIDE, TO ENABLE SAID SECOND CURSOR TO MOVE ALONG SAID SECOND SLIDE, A SUPPORT MEMBER CARRIED BY SAID SECOND CURSOR, MEANS FOR PIVOTING SAID FIRST FLAT STRIP TO SAID SUPPORT MEMBER ABOUT A THIRD PIVOT, AND A RULE CARRYING A THIRD GRADUATED SCALE, SAID RULE BEING CARRIED BY SAID SECOND CURSOR.