6 



The black irregular line around each drain is a sug- 

 gestive contour line with equal elevation and slope 

 towards the main creek. Notice that all trees were 

 killed below and some above this line in field No. 5, 

 while in field No. 1 not a tree was lost. 



Fields Nos. 6, 7 and 8 are shown only for relative 

 positions. Field No. 3 shows the same general result 

 as shown in Map No. 2, Field No. 1. 



Map No. 2 (page 8) — This map shows 160 acres set to 

 oranges with the exception of a small area in the soutli- 

 east corner. The area contains one brook in the north- 

 east section and a creek extends across the south-east 

 corner bordering the south. You will note in field 

 No. 2 of this map that 25 per cent, of the trees along the 

 drain were killed. The woods north, east and south of 

 this drain kept the north wind from dispersing the cold 

 damp air which settled and caused freezing. 



When there is perfect air drainage for tlie field as a 

 whole, and the field slopes in the direction of wind- 

 flow, the trees will not be killed on the level area and 

 as far down the hill as the circulating air disperses the 

 icold damp air. In case of a gradual slope of about 

 one or one and one-half inches per foot, where the wind 

 current crossing a valley at right angles, or where there 

 is a forest wind-stop at the foot of the hill, the circu- 

 lating air does not seem to follow down the hill-side, 

 but passes over at the height of the wind stop or the 

 nearest land elevation l)eyond, thereby permitting the 

 cold, dense air to settle toward the foot of the hill. In 

 a case of this kind described in map No. 2, field No. 1, 

 a greater per cent, of the trees w^ere killed in each suc- 

 ceeding area from the level area to the draw, creek or 

 lowest areas. 



Field No. 1 of map No. 2 show^s this condition. The 

 wind coming across the level from A to B will not al- 

 low the cold, damp air to settle. No trees are killed as 

 the wind passes B to C. The wind is yet near enough 

 to the surface to disturb the cold, damp air and ])rc- 

 vent it from settling. No trees are killed. Farther 

 down the hill circulating air does not come near the 

 ground and the killing increases, as shown in the field 

 drawing and graphically to the left of the map. In 

 this instance there was a forest at the foot of the hill 

 and high land just across the valley. 



ORCHARD SITE 

 Close observation covering a period of several years 

 in South Alabama relating principally to the selection 



