KOBISONJ 



USE OF 1 1 E. I Til Ell MA PS A S SO I R C E MA 7 'ER I . I LS 263 



Unusual Phenomena. These will include coronas, fogs, 

 rainbows, auroras, mirages, hailstorms, first snow-falls, floods, 

 etc. 



Probabilities. Speculating on the effects of observed con- 

 ditions taken in connection with the use of the daily weather- 

 maps opens a field that would require another chapter to review. 



THE USE OF WEATHER MAPS AS SOURCE MATERIALS 



By C. H. ROBISON, Department of Nature-Study and Geography, State Normal 



School, Upper Montclair, New Jersey 



If a public school is favored with a daily Weather Bureau 

 service, the maps are too often looked upon by the pupils as a 

 thing of mystery, and by the teacher as so much rubbish when 

 two days old. The best kind of laboratory work can be done 

 with these maps by pupils long before they can make any sense 

 out of the treatment of the topic, weather, as found in many of 

 the grammar school geographies. 



These maps should be saved for future use. When a large 

 number have been accumulated, they may be culled over, the 

 representative ones picked out to show well developed "highs" 

 and "lows" respectively, and the others used to show progressive 

 weather changes through a short series of consecutive days. These 

 representative maps might form the basis of several lessons. 

 Thus, one or two days should be given up to simple explanations 

 of the facts that air occupies space and exerts some pressure — 

 upwards as well as downwards. The demonstration of these 

 facts calls for nothing more elaborate than a dish, a fruit jar, 

 a tumbler, and a straight lamp chimney. 



The first lesson with the weather maps may well confine 

 itself to a discovery, from examination of the maps, of the fact 

 that the winds of a general storm travel about the center con- 

 trary to the direction of the hands of the clock; and that the 

 currents tend inward rather than outward. There should be a 

 map for each two pupils. 



This lesson might well be separated from the second lesson 

 on the weather maps by a demonstration of the convection of 

 air currents by means of the time honored but effective apparatus 

 consisting of two lamp chimneys standing over perforation-; in 



