Page:Popular Science Monthly Volume 32.djvu/509

Rh was asked admitting of but one answer, the mental process being simply an act of memory. It is also possible to ask a question that allows of several answers, and in this case a little more time is needed; it takes longer to mention a month when a season has been given than to say to what month a season belongs. The mind can also be given still further liberty; for example, a quality of a substantive, of a subject or object for a verb, can be required. It takes about one tenth of a second longer to find a subject than to find an object; in our ordinary thinking and talking we go on from the verb to the object. If a particular example of a class of objects has to be found, as "Thames" when "river" is given, on the average a little more than half a second is needed. In this case one nearly always mentions an object immediately at hand, or one identified with one's early home; this shows that the mind is apt to recur either to very recent or to early associations. Again, I need one second to find a rhyme, one fifth of a second longer to find an alliteration. The time taken up in pronouncing an opinion or judgment proved to be shorter than I had expected; I need only about half a second to estimate the length of a line, or to say which of two eminent men I think is the greater.

Our thoughts do not come and go at random, but one idea suggests another, according to laws which are probably no less fixed than the laws prevailing in the physical world. Conditions somewhat similar to those of our ordinary thinking are obtained, if on seeing or hearing a word we say what it suggests to us. We can note the nature of the association and measure the time it takes up, and thus get results more definite and of greater scientific value than would be possible through mere introspection or observation. By making a large number of experiments, data for laws of association can be collected. Thus, if a thousand persons say what idea is suggested to them by the word "Art," the results may be so classified that both the nature of the association and the time it occupies throw much light on the way people usually think. Such experiments are useful in studying the development of the child's mind; they help us to understand the differences in thought brought about by various methods of education and modes of life, and in many ways they put the facts of mind into the great order which is the world.—Nineteenth Century.

that the surface of the earth will in a few years be all explored for ordinary geographical purposes, Professor Boyd Dawkins has called attention to the fact that besides the geography in space, there is a nearly untouched field of geography in time. It concerns the ancient changes by which the earth's surface has come to be what it Is, and the geographical outlines as they appeared at the various geological periods. In working this field geographers would do as good geographical work as in recording any of the facts which are brought from the interior of Africa or from the polar regions.