National Geographic : 1900 Feb
PRACTICAL EXERCISES IN GEOGRAPHY and southing of the sun (or its movement in declination, declination in the sky being the equivalent of geocentric * latitude on the earth). The fact of seasonal change having been already recorded in a most elementary way, let a second record be made in connection with a search for the causes of change, as follows: At intervals of a fortnight or a month determine the midday altitude of the sun. At similar intervals determine the time, and if possible the compass direc tion, of sunrise and sunset.t Again, at similar intervals, have the scholars, or at least the brighter ones, note the star groups that ap pear in the east shortly after the time and opposite to the point of sunset. All the facts thus determined vary systematically and in cor relation with one another. The discovery of their system of change and of the correlations in the system should, if possible, be reserved for the scholars. Their intelligence is only half developed if the dis coveries that they can make are made for them. In such case it may be claimed thattime is saved,and that the results reached are the same; but it should be seen, on the other hand, that the scholars lose much appreciation of the result if they do not find it for themselves, and that they will fail entirely to acquire the power and the habit of dis covering if they have no practice in it. If American schools are de veloped on a truly democratic basis, as befits republican institutions, one of their chief values will be that they aid in giving every boy and * This word, "geocentric," is inserted here in order to escape the criticism of the carping and captious. In oral explanation with teachers or scholars I should omit it and accept the consequences. In printed statement it is necessary to be more circumspect. If any member of a class should rise by his own exertions to an understanding of the difference between geo graphic and geocentric latitude, he would deserve and appreciate the fuller explanations that could be given in response to his questions; but to introduce into a first statement so fine a point as is implied in the use of geocentric would unnecessarily and unwisely delay and com plicate progress. t It is manifest that this requires observations outside of the school session and sometimes at rather inconvenient hours. But I would protest against the implication contained in objec tions to outside work, that lessons are so distasteful that none of the scholars will willingly give a little of their free time to such details as are here suggested. Early summer sunrise can be timed from sunset when it has been discovered during the winter that sunrise and sunset occur symmetrically before and after midday, or the moment when the sun reaches its highest altitude (meridian culmination). The general adoption of standard time introduces some confusion here, for it is desirable that sunrise and sunset should be recorded in local solar time. A watch kept to such time by observations of the sun at midday is useful in this connection. This is easily done when a north mark has once been established. The watch will then give the necessary correction for the steeple clocks and factory whistles, by which some scholars may have to make their morning and evening records. A pocket compass for measuring the direction of sunrise and sunset may be lent to those scholars whose homes give the best view of the horizon. Compass readings should be cor rected for local variation of the needle to give true bearings. The direction of early sunrise may be determined from that of late sunset when it has been discovered that the two are sym metrical with respect to the true meridian.