10 • The Bulletin. 



THERMAL FRUIT BELTS. 



In mountain regions, where elevations are greatest, the maximum 

 of exemption from frost is experienced. There are many places in 

 our mountains known as thermal belts, which are said to be entirely 

 free from frost. Whether or not this is claiming too much, it is cer- 

 tain that distinct lines can often be seen separating bright, _ fresh 

 verdure above and blackened, frost-bitten foliage below. Similar 

 lines of demarcation can be seen in spring between the early growth 

 on the hillsides and the dormant buds of the valley below. In sum- 

 mer over the same area can be seen a distinct cloud line marking the 

 height of the fog in the valley below, while above it on the hillside will 

 be a cloudless air bathed in sunlight. In the fall, when frosts have 

 claimed all the tender vegetation of the valley, there will be seen, 

 longitudinal bands skirting the hillsides, showing for a month or six 

 weeks all the freshness of summer. Though the exact borders of 

 these thermal zones cannot be located with precision, their general posi- 

 tion is fairly constant. Orchards planted on thermal belts are re- 

 markably regular in fruit bearing. There are many orchards in the 

 mountains where old settlers claim they have never seen a failure in 

 a crop from frost. The reason for these peculiar phenomena is 

 undoubtedly the draining of cold air from the hillsides and its strati- 

 fication in the valleys below. There are other circumstances con- 

 nected with thermal belts that have not yet been been fully worked 

 out. By the aid of self-registering instruments for recording tem- 

 perature and humidity we are at present working on these problems, 

 and hope to have information to give later. However, there is at 

 present sufficient practical evidence of the value of thermal belts in 

 frost protection. Fruit growers should not fail, where possible, to 

 take advantage of them in orchard planting. 



DIRECTION OF SLOPE. 



There is considerable difference of opinion among fruit men as to 

 what is the best direction for the slope of an orchard. The prefer- 

 ences of different men of experience are so variable as to include every 

 point of the compass. Each slope has its advantages and its dis- 

 advantages. A northern slope is a little later in forcing growth in 

 spring, and on that account the bloom is less apt to be nipped by late 

 spring frosts. On the other hand, the fruit on northern slopes, when 

 developing, gets less sunlight and does not have the high colors of that 

 grown on southern slopes. As it is the sunlight that paints the bright 

 colors, the southern slopes always produce the richest-tinted fruit. 

 Southern slopes, too, are the ones from which the sun drinks the 

 moisture most rapidly. They are apt, therefore, to be droughty, and 

 unless the trees are well cultivated or mulched they will produce small 

 fruit. On account of the continuous loss of moisture from southern 



