OBSERVATIONS AND PREDICTION OF THE WEATHER 81 



Other Signs. Spiders are very sensitive to atmospheric changes. Every 

 twenty-four hours the spider makes some alteration in its web to suit the 

 weather. When a high wind or heavy rain threatens, the spider may be seen 

 taking in sail, shortening the rope filaments that sustain the web structure. 

 If the storm is to be unusually severe or of long duration, the ropes are 

 strengthened, as well as shortened. 



On the contrary, when you see the spider lengthening the slender fila- 

 ments, it is certain that calm, fine weather has set in, the duration of which 

 may be measured by their elongation. When the spider sits quiet and dull in 

 the middle of its web, rain is not far off. If it be active, however, and con- 

 tinues so during a shower, the ram will be of brief duration, and sunshine wil 

 follow. When you see the spiders coming out of the walls more freely than 

 usual, you may be sure that rain is near. 



Leech Barometer. If there is an aquarium in the school room the 

 following material will be found an interesting addition to this work. 



Leeches are exceedingly sensitive to weather changes. Fill a jar with pure 

 water and cover the opening with muslin, after placing a leech inside. During 

 fine weather the leech lies motionless at the bottom of the jar. When rain 

 is coming, it climbs to the upper part and seems generally unsettled. At 

 the coming of wind or thunder, it becomes extraordinarily active, moving 

 rapidly about and scarcely staying in one place for ten seconds. 



Frog Barometer. The same kind of a jar that was used for the leech may 

 be used for the frog barometer. In this case a small wooden ladder should 

 be used, and the water in the jar should not come beyond the third step. 

 When the weather is likely to be fine and dry, the frog remains below the 

 water most of the time. At the approach of rain it climbs up the ladder, and 

 sits, entirely out of the water; as the weather becomes clear, it -returns to the 

 water. In both barometers, change the water at least once a week. 



QUESTIONS 



1. What are some of the signs of approaching rain? 



2. How are people who are troubled with rheumatism or neural- 

 gia affected by the weather? 



3. What weather flags would you use to-day? 



QUESTIONS FOR INVESTIGATION 



1. How are you physically conscious of an approaching storm? 

 What conditions of the air make you feel the approaching storm? 

 How long before the arrival of a storm are you able to predict 



its approach? 



2. From what directions does the wind usually blow before a 



