METEOROLOGY. 697 



California wheat crop may receive incalculable damage. In Oregon, 

 as in Ciilifornia, the hot winds are especially injurious in June. IVIr. 

 B. S. Pague, of the National and the Oregon ^^^ather Service, states: 



"Three days of hot winds may reduce yields from 30 bu. per acre to wheat not fit 

 e\en for haj'. The character of the wind is abnormal dryness, varying in force from 

 6 to 15 miles per hour, and accompanied by temperatures of from 75 to 90 F. The 

 dry wind continues during the night, abating some, while the temperature has its 

 diurnal change." 



The California fruit grower has been among the earliest to recognize 

 the efficacy of timber belts as a protection against the damaging effect 

 of wind, and around many of the citrus groves of southern California 

 may now be seen rows of eucalyptus or other trees for wind protection. 



The grent western plains offer the greatest sphere for the operation 

 of timber as wind-breaks, for this is the natural home of all the 

 destructive winds. 



IMany attempts at tree planting on the western plains have met Avith 

 poor success because they have been imi^roperly conducted. The 

 aridity of the climate requires that suitable varieties be selected and 

 properly combined; that a sufficient mass of foliage be obtained to 

 create favorable conditions of growth, and then that the trees should 

 not be left to themselves, but should be as thoroughly cultivated as 

 any croj) of grain. Sufficient experience has now been attained to 

 demonstrate that, Avhen these conditions are observed, timber strips can 

 be successfully grown in Kansas as far west as the one hundred and 

 first meridian, or beyond the present boundaries of successfnl agricul- 

 ture. The last report from the experimental station at Garden City, in 

 western Kansas, states that the timber strips planted for wind-breaks 

 have made a marvelous growth. These stri]is consist of four rows of 

 black locusts bordering all sides of a 100-acre lot, and several rows of 

 cotton woods on one side of an 80-acre lot. 



The protective effect of standing timber as an obstruction to the 

 wind being recognized, it is important to know to what distance this 

 protection is extended. The extent of the protective action of a verti- 

 cal obstruction is accurately exemplified by the distance to which a 

 snow bank extends on the leeward side of a fence. This is the width of 

 the protected strip and we desire to know its ratio to the height of the 

 obstruction. Mr. Barnard, of Pawnee County, Nebraska, and Judge 

 Whiting, of Iowa, are authorities for stating that the protection amounts 

 to 1 rod (16J feet) on the ground to every foot in height of the protect- 

 ing trees. Other writers give a somewhat less ratio for the distance of 

 protection, but an average estimate is that a solid belt of trees creates 

 a calm area on its leeward side which is, at the ground, from 11 to 16 

 times as wide as the height of the trees. 



Observation also indicates that barriers and obstructions, like build- 

 ings and trees, diminished the general velocity of the surface wind 

 beyond the limits of their immediate protective influence. These data, 



