Range finder

An apparatus for determining the distance on the earth between (a) a point below an observation point at a known height and (b) the base of an object of a known height, the apparatus comprising;

• a base having an A and B mirror pivot hole, said pivot holes being spaced from one another, a first and a second lever arms each having a straight bottom edge,
• the first lever arm being pivotally mounted to the base for swinging movement about the A mirror pivot hole, and
• the second lever arm being pivotally mounted to the base for swinging movement about the B mirror pivot hole,
• an A and A B planar mirror each having a reflective surface,
• the second lever arm including the B mirror and the first lever arm including the A mirror, the reflective surfaces of each of said mirrors facing one another and being substantially parallel,
• an object height adjustment assembly comprising, a carriage,
• the base including guide means defining an elongate track being a longitudinal center line and, means connected for movement along the track of the base,
• the carriage including a member having a first end perpendicular to the center line of the elongate track, means on the carriage captivating the member for movement perpendicular to the center line of the track, the first end of the member bearing against each of the lever arms for tilting the levers upon movement of the member, and biasing means on the base normally urging the lever arms into engagement with the member,
• the member having a second end comprising an operator means for moving the member, and including reference markings,
• an elongate previously calculated distance scale on the base adjacent the elongate track, and the carriage including reader indicia having a first reference line perpendicular to the elongate track, and the reader indicia further including a cross-referenced line perpendicular to the reference line and intersecting with the reference line.