RESULTS OF MEASUREMENTS. 41 



parison of the wind movement at a point in the open with that at 

 a point 5-ht. in the lee of the windbreak shows that a wind which 

 reaches a velocity of 25 miles per hour in the open will in the shelter 

 of a good windbreak have a velocity of only 20 per cent of this, or 

 5 miles per hour (see diagram 15). 



DAMAGE TO CROPS. 



In August, 1908, an opportunity was afforded for observing the 

 effect of a violent wind upon a field of corn in the shelter of a wind- 

 break which consisted of three rows of willows, 80 rods long, with a 

 mean height of about 28 feet. With a wind velocity of at least 50 

 miles per hour about half of the corn in unprotected portions of the 

 field was blown to the ground, while the remainder was bent about 

 halfway to the earth. Since the ears were "in the milk" at the 

 time, the field, in its damaged condition, could not mature more 

 than one- third of a normal crop. 



In the shelter of the windbreak there was no damage. This held 

 true to a distance of about 6-ht., or 10 rods. Between 6-ht. and 

 8-ht. there was very slight damage to the corn, perhaps 10 per cent 

 loss. From 8-ht. to 12-ht. there was a loss of perhaps one-fourth 

 of the crop, while beyond the latter point, the benefit from the wind- 

 break was not appreciable. Assuming a normal yield of 45 bushels 

 per acre, the protective value of the windbreak in this storm may 

 be valued at 260 bushels. In addition, the windbreak has more 

 than paid for the ground occupied through its present value in posts 

 and fuel. The posts alone are estimated at $317. 



Mr. O. B. Galusha, 1 of Illinois, writing in 1869, describes a storm 

 in 1862 which struck the northern part of Illinois and did so much 

 damage to standing corn that the monetary loss would be almost 

 sufficient to pay the expenses of planting 4 miles of shelter belt on 

 every section of land in the region affected. 



MOVEMENT OF SOILS. 



The effect of winds in moving loose soils has often proved disas- 

 trous to farmers. There have been many instances of great damage 

 from this source, but in years when winds are not prevalent and 

 when moisture is abundant, they are likely to be forgotten. 



Prof. F. H. King 2 described in detail the effects of a strong north- 

 east wind in the northern part of Wisconsin in moving the soil of 

 cultivated fields. The wind occurred immediately after a heavy 

 rain, and in a very short time the surface soil was dried out, the 

 smaller particles being carried off the fields and deposited wherever 

 the velocity of the wind was checked. The value of fences, hedges, 



1 Report on Forestry, 1877; F. B. Hough. 



2 Bulletin 42, Wisconsin Agricultural Experiment Station. 



