308 STATE POMOLOGICAL SOCIETY. 



ble influence to prevent injurious freezing of trees and buds during winter, aucl 

 injury from frost during spring and fall. For the same principles that govern 

 the phenomena of ordinary frosts governs that of extreme winter cold in this 

 region. And for the purpose of making this clear I will occupy a few moments- 

 in explaining the philosophy of ordinary frosts. Every one has observed that 

 ordinary frosts vary greatly in their severity, low ]))aces, level lands and basins 

 or depressions suffering more injury than side hills, knolls and ridges. On a 

 clear still night heat radiates from the surface of the earth into space. As 

 this radiation goes on, tlie surface grows colder and colder, if level the air 

 remains stationary, and falls in temperature with the surface of the earth, at 

 first the moisture of the air is condensed and forms dew, at S'-i" Fahrenheit it is 

 crystallized into hoar frost, if it sinks still lower the sap of tender plants is 

 frozen, expands, and bursts or injures the cells and kills the plant. Cold air is 

 heavier than warm air, and the colder it grows the heavier it gets. On side hills, 

 knolli, and ridges as radiation cools the surface, the air becomes heavier and 

 runs down the hill to the valley or plain below, and warm air takes its place ; 

 this in its turn grows dense and passes dowji, forming a current of air down 

 the hill, leaving none of it at rest long enough to reach the freezing point. If 

 the valley is enclosed so as to form a basin, the cold air '"draining" into it may 

 fill it up so tliat the frost will reach up the side hills to the level of the dam 

 which encloses it. But where the drainage reaches a body of water, heat 

 escaping from the water re-heats the air, causing it to rise again and flow back 

 to take the place of that which is flowing down the hills. In the coldest nights 

 of winter the difference between hillsides and enclosed basins is surprising. In 

 one case Messrs. Avery and Marshall, of Old Mission, found a difference of 22'' 

 in less than one hundred feet elevation, and Messrs. rarmelce and Brinkman 

 11° in fourteen feet. AVhere the valley or hillside opens without obstruction to 

 the bay or lakes the difference is not so great. I find on my farm, which 

 descends rapidly towards Grand Traverse Bay, a difference on such nights of 

 from four to six degrees per each hundred feet, and in one instance, February 

 9th, 18G5, the coldest night ever known in this region, it varied ten degrees tO' 

 the hundred feet. "When we consider how close the margin is between absolute 

 exemption and total destruction of the tender varieties of fruit trees by freez- 

 ing, we shall see how important this matter of atmosplieric drainage is. With 

 -13° the peach is comparatively safe, at -15° the tree is in danger, and -22° is 

 almost certain destruction. An hundred feet elevation, with open drainage to 

 water, may determine the difference between a crop of peaches and a dead 

 orchard. And in an enclosed valley or basin twenty feet may do the same. If 

 my reasoning and conclusions are correct, it is easy to determine the extent of 

 this territory best adapted to the general cultivation of fruit. Upon all the 

 hillsides with free atmospheric drainage to Lake Michigan — Crystal Lake, 

 Glen Lake, Carp Lake, Grand Traverse B'ay, Elk Lake, Round Lake, and 

 Torcii Lake — peach orcliards may bo planted witli as much safety from winter 

 killing as at any place north of the latitude of Cincinnati. Upon tlie terrace 

 around Grand Traverse Bay and the lower inland lakes, where the orchards of 

 this country were first planted, the winter of 1875 demonstrated that it is 

 unsafe to plant peaches, i)lums, cherries or pears. And upon tlie level 

 plateaus mentioned nothing but the hardiest trees siiould be planted. But 

 grapes may be cultivated with success upon every hillside in the wiiole region 

 "where the elevation above the nearest level is sulficient to protect them from 

 late spring and early fall frosts; for if priuied and laid down in the fall as they 



