The Austin Photo Interpretometer is a combination instrument which is an invaluable aid for the photo interpreter. It consists of a stereoscope together with a base having scales for making very close measurements. In effect, it operates as a stereo scope, a height finder, and a measuring device for making linear photographic measurements.

The stereoscope is fitted with folding legs and is ad justable for inter-ocular separation. It is used with out the base for stereoscopic examination of the photographs. Figure 1 illustrates the instrument.

The stereoscope is affixed to the base by inserting the legs into four holes. See figure 2. When set up in this manner, the Photo Interpretometer can be used as an instrument for making linear measurements or as a Height Finder.

The base of the instrument contains two moveable. transparent plates. The right-hand late will hereinafter be referred to as the "X" slide. his slide contains two horizontal scales, one with graduations which equal .005 feet and the other with graduations which equal one millimeter. This plate o contains a small dot with a long pointer above.