Page:Popular Science Monthly Volume 44.djvu/789

Rh dog. One of these, the devious path of a bright six-year-old Irish girl, is reproduced in Fig. 12. Lubbock's ants might be pardoned for smiling should they chance to see this tracing.

The search line of an intelligent dog is given in Fig. 11. His eyes were covered, but he evidently had a strong impression that the ball had been thrown in the direction I happened to be facing. Resemblance between this and tracings of a number of the pigeons is quite evident.

The bearing of the above upon the problem of search as exhibited by the homing pigeon requires no detailed statement. In a word, the pigeon uses a logic of search which is common to animals generally, and there is no evidence that he employs anything else. His power of rapid and prolonged flight makes it possible for him to spin his search lines over vast areas and so carry them beyond our vision and lift them into the realm of mystery.

In such cases the time consumed furnishes an important check. Of a large number of birds sent away by rail for longer flights, not one made the return trip in less time than would have enabled him to fly on the involute of a circle from the place of liberation. This refers to "first flights." The best time made was twenty-six miles in five hours and nine minutes. Three other birds liberated at the same time failed to return. Letting the distance to which a prominent landmark is visible be three miles, a fair estimate for pigeons with some training and over broken country, the least length of an involute of a circle which would bring a bird from a distance of twenty-six miles to within sight of the loft is two hundred and nineteen miles. In five hours it is not likely that the pigeon flew less than two hundred and fifty miles.

One thing which causes the search lines of the pigeons to swerve from the ideal curve of search upon a uniform field is that the field in their case is never uniform. A house of any kind, especially a red building, or, upon the lake, nearness to land,