Fig. 6. This is a shade less ideal. The searcher, supposing him to be at the center, first looks around as far as he can see, then goes straight out twice the distance at which the object is visible, and begins following circles, each one being twice the visible distance from every other. A number of rectilinear figures were
Fig. 5. Involute of a circle, the figure suggested by Professor Story as the ideal curve of search.
received, types of which are reproduced in Figs. 7 and 8. These are a stage above the fundamentally logical. They clearly belong to the realm of the practical. We might call them "Yankee" search curves. They are practical, of course, because it is easier to follow a straight line than a curve.
A simple experiment was next devised, in which a person