Device for determining angle relationships of or between planes

A device for determining angle relationships between planes, such as in geological structures, comprising:

• a first disc member having planar surfaces;
• a family of concentric circles on one of said planar surfaces of said first disc member each of said circles indicating an angle from at least part of the range from 0.degree. to 90.degree. which is the complement of the half angle of one of a family of notional right circular cones of equal height, each of said circles being the base of the cone of which the angle it indicates is the complement of the half angle;
• a second disc member having planar surfaces;
• a family of curved lines on one of said planar surfaces of said second disc member, each of the curved lines of said family passing through a common point and each of said curved lines being a portion of a circle each of which has its center on one common line extending radially from the common point, each of said curved lines indicating an angle from at least part of the range from 0.degree. to 90.degree. which is the complement of the half angle of one of a family of notional right circular cones of equal height, each cone having a base with a radius equal to the diameter of the curved line which indicates the complement of the half angle for that cone;
• a base member on which said first and second disc members are mounted with the center of said family of concentric circles being coincident with the common point of said family of curved lines, one of said disc members being rotatably mounted on said base member and the other being non-rotatably mounted on said base member, said base member having thereon a horizontal bearing degree scale in relation to which one of said disc members is rotatable;
• a ruler member extending across said first and second disc members and having a ruler edge thereon;
• means for mounting said ruler member on said base member, said mounting means including means for rotating said ruler member with respect to said planar surfaces of said disc members and said base member and said mounting means including means for lateral movement of said ruler member with respect to said planar surfaces of said disc members and said base member;
• and
• at least one of said first and second disc members being transparent so that said family of concentric circles and said family of curved lines can be viewed from one side of said disc members in overlapping relation.