Parallel rule
OwnerMichael Humphriesinventor
Life of this patent
Estimating the term…
Abstract
A parallel rule is disclosed having two component rules (4, 6) each providing one of two opposed parallel straight edges. A linkage (10) allows relative movement of the rules in a direction orthogonal to the straight edges but prohibits relative movement in a direction parallel to the straight edges. At least one component rule has at least one through hole (12)suitable to receive the point of a pencil.
Claims12
A parallel rule comprising two component rules each providing one of two opposed parallel straight edges, and a linkage allowing relative movement of the rules in a direction orthogonal to the straight edges but prohibiting relative movement in a direction parallel to the straight edges, wherein at least one component rule has at least one through hole suitable to receive the point of a pencil so as to make a line of latitude or longitude on a chart and the other of said component rules has a through hole in corresponding position to said at least one through hole of said one component rule.
A method of making a line of latitude or longitude on a chart using a parallel rule comprising two component rules each providing one of two opposed parallel straight edges, and a linkage allowing relative movement of the rules in a direction orthogonal to the straight edges but prohibiting relative movement in a direction parallel to the straight edges, wherein a first of said component rules has at least one through hole suitable to receive the point of a pencil so as to make a line on a chart, the method comprising aligning the straight edge of the second component rule with a first line of longitude or latitude at an edge of a chart, placing a pencil point in the through hole in said first component rule and in contact with said chart, and;
- while holding said second component rule still, moving the first component rule and the pencil point laterally away from said second component rule for making a second line on said chart orthogonal to said first line.
Dependencies are inferred from the claim text.