ELEMENTARY FORESTRY 387 



is so, why is it ? What do the children know about 

 the way the snow melts in the spring ? Where does 

 it melt first ? Where can they find the last snow bank 

 in the spring ? Bring out the fact that the snow melts 

 slowly in the woods, allowing the water to soak into the 

 ground. 



We have already seen that the leaf mould, with its mass 

 of tangled roots, and the loam of the forest floor absorb 

 water like a huge sponge and give it up slowly to the 

 springs below and to the leaves of the trees above. It 

 has been found that only from one-half to one-quarter as 

 much water evaporates from forest land as from land 

 under cultivation, and to gain a hint as to one of the 

 factors that cause this we may make some further experi- 

 ments upon soil of different kinds in the tumblers. 



Let the class arrange and label eight tumblers of the 

 same size and shape and, having the materials dry, fill to 

 within one-half inch of top with the following materials : 

 gravel. No. i ; sand, No. 2 ; barren soil. No. 3 ; rich loam, 

 Nos. 4 and 5 ; about one inch each of gravel, sand, and 

 loam in order, the loam on top. No. 6 ; two inches of rich 

 loam with one inch of finely pulverized leaf mould on top. 

 No. 7 ; water, No. 8. Weigh each and, unless it is 

 desired to study fractions, bring them all up to even 

 grams to start with by adding a little of the appropriate 

 dry material. Then pour into each, except the last, an 

 equal amount of water, say 100 cubic centimeters. Place 

 the tumblers somewhere in the schoolroom where the sun 

 will not shine on them and every day at the same time 

 weigh them all carefully to see how much water has 

 evaporated from each. Set down the weighings on the 



