National Geographic : 1900 Feb
PRACTICAL EXERCISES IN GEOGRAPHY may be convinced that if their observations were minutely accurate the size of the earth could be estimated from even so short an arc as that which they can pace during a recess interval. If a hill rises near the school the convexity of the hill may be taken to imitate the rotundity of a little earth. Two parties stationed out of sight of each other on the north and south slopes of the hill, and on a north and south line, may determine the sun's noon altitude with reference to the slopes of the hill (which imitate the curved, level surface of a little earth), and then measuring the arc between their stations, the size of a small earth to which such a hill would fit may be determined. In the absence of a hill, a useful substitute may be provided in a school yard by placing two tables or boxes in a north and south line fifty or a hundred feet apart, tilting their upper surfaces away from each other, and then proceeding on the pretense that the table surfaces are parts of a little earth, whose convex meridian may be indicated by the tops of a row of stakes between them. The curved surface of a globe in a school-room may be used to explain the geometry here involved, but outdoor work should not be altogether replaced by such indoor sub stitutes. Nothing can so well give the sense of the real great earth as outdoor observations. Two schools can profitably cooperate-to measure the size of the earth. On a certain day agreed upon beforehand the midday alti tude of the sun is determined at each school. The length of the meridian arc between the latitude circles of the two schools may then be measured on a good map and the proportion of Eratosthenes again employed to find the unknown quantity. If each school de termines its own latitude, the difference of latitudes replaces the difference of the sun's midday altitude on a given day, and then no agreement as to the day of observation is necessary. Why is it that nature study of this kind, so appropriate to the inhabitants of a rotating globe, is not introduced in our lower schools ? Is it because of the supposed difficulty or the actual simplicity of the necessary observations; on account of a recognition or a neglect of their value; on account of a confidence in the innate ability of young scholars or a mistrust of their powers; or on account of preparation or lack of preparation on the part of the teachers? To the best of my belief, this is merely one of the many cases in which the real mental activity of school children is benumbed by substituting recitations of words for live performance.