64 PRACTICAL EXERCISES IX GEOGRAPHY 



above. Simple jmrallelism between text and practical exercises is 

 therefore out of the question, and we must be content if some 

 efliective correlation between the two is gained instead. In order to 

 give specific indication of the character of various practical exercises 

 and of the correlations that may be established between such exer- 

 cises and l>ook work, let me open the subject with some examples 

 ai)propriate to the study of that interesting chapter of physical 

 geography which is often given a forbidding appearance under the 

 name of' mathematical geography." 



The Etirth as a Globe. — It is seldom that justice is done to the op- 

 portunity of practical work under the heading of the earth as a globe. 

 The ditliculties that stand in the way of various ol)servational exer- 

 cises may certainly be overcome if their accomplishment rather than 

 the maintenance of a set order of school periods is made the object 

 in view. Many series of observations that cannot and need not be 

 made by a whole class may be made by scholars singly or in jiairs ; 

 the avoidance of such exercises, because of the disorder that tlu\y ma}' 

 create, does not speak well for the discipline or for the si)irit of the 

 school. Several of these exercises are best performed under the name 

 of nature study in lower grades than the high school ; the}' are men- 

 tioiK'd here because if, as is too often the case, they have not been 

 perfornicil in their proper place they should be given place in the 

 high school ; but it is manifest that such apian disarranges the high- 

 school course in physical ge()gra[»hy and retards the attainment of the 

 grade that it deserves. 



Shape of the EnrOi. — The only ol)servational proof of the glol)ular 

 shape of the earth that is within the reach of young scholars is ofl'ered 

 at the time of an eclipse of the moon. Such an opportunity should not 

 be lost sight of. The edge of the earth's shadow always having a 

 curved outline, the earth must be round, as Aristotle perceived four 

 centuries before the Christian era. The time-honored proof afforded 

 by the gradual disappearance of ships at sea is available only at the 

 sea-shore; it is interesting to note that this proof was first men- 

 tioned by Strabo. Acce[)ting the globular form as a fact, the horizon 

 plane, touching the earth's surface at the observer's station, extends 

 indefinitely on all sides ; the visible sky lying above, the invisible sky 

 lying below the i)lane. As long as the earth is thought of as a large 

 body in comi)arison to the dimensions of the sky vault, it will prob- 

 ai;)ly be more or less consciously believed that the smaller half of the 

 sky is above and the larger part is below the horizon of an observer. 



