82 TALKS ABOUT THE SOIL. 



through the loose soil ; and both air and water bring 

 elements that combine with elements in the soil, dis- 

 solving some, and forming others into new combina- 

 tions. Even the hard sand in the soil is affected and 

 disintegrated, and made finer and softer. Thus by 

 tillage we assist the air, water, heat, and cold, to con- 

 tinue their ancient work of making new soil out of 

 old materials. We can see no change in the soil ; but 

 the plant is aware that the soil has been improved by 

 tillage, and by its improved health and vigor tells us 

 what has happened. This work of stirring up the soil 

 in flower-pots is one of the surest ways of keeping 

 house-plants in good health, and should be done at 

 least twice every month. 



xvn. AN ANCIENT TOOL. The oldest tool for 

 improving the soil was probably a forked limb from a 

 tree. With this rude tool, which was the first sugges- 

 tion of a hoe, the ancient cave-man scratched up the 

 soil in such bare spots as he could find in pre-historic 

 woods, and made a place for his poor, small seeds. 

 No man can tell where or when this work began. It 

 is utterly lost and forgotten. Perhaps the limb of the 

 tree was broken or cut off with stone hatchets, and 

 looked like a in Fig. I. 



Then some more ingenious fellow suggested finding 

 a longer limb, and making the shorter arm sharp. 

 By this change the crooked stick could be dragged 

 along the ground by the long handle, while the sharp- 

 ened branch made a rough furrow in the soil. (See b 

 in Fig. I.) By dragging such a sharpened stick over 



