812 STATE BOARD OF AGRICULTURE. 



low iiiiiiiiinim in one soil iind n low inaximiim aiul liigh minimum in 

 another. 



The uniformity of average temperature throughout the year except 

 during the short period in the spring when thawing was taking place, 

 of the different types of soil wlien their surface was covered with a thin 

 laver of sand, is really renuir]<able. It sliows that there was onlv one 

 intrinsic factor, the heat of fusion of ice, which predominated and caused 

 a variation in their average temi)erature and especially between sand or 

 gravel and peat. All tlie other intrinsic factors existed in such a com- 

 pensating degree and order in these different kinds of soil that they 

 caused and maintained in them an equal magnitude of temperature, after 

 complete thawing took place. 



When these same types of soil, however, were not covered with a thin 

 layer of sand but their natural surface was allowed to be exposed to 

 the atmosphere somewhat different results Avere obtained. Their average 

 temperature, instead of being equal throughout the year except during 

 the process of thawing, was about the same only during the fall and 

 winter months, but varied somcAvhat during the spring and summer 

 months. During the latter seasons the sand and gravel would have the 

 highest average temperature, the clay and loam slightly lower, and peat 

 the lowest. The difference, however, between the mineral soils was com- 

 parativly small, but the variation between the sand or gravel and peat 

 was quite appreciable, especially in the early spring when thawing was 

 taking place. By the commencement of fall, however, these differences 

 would disappear and all the soils then would have the same magnitude 

 of average temperature, and would continue to be equally warm until 

 the next thawing period, in almost exactly the same way as when they 

 were covered with the thin layer of sand. In the spring the peat would 

 not thaw and its temperature would not approach that of the mineral 

 soils after complete thawing, as rapidly as when its surface was cov- 

 ered with the thin layer of sand. 



Besides the average temperature the order of the maximum and mini- 

 mum temperature also differed in the various types of soil under the 

 two surface conditions. As previously stated when the surface of these 

 soils was covered with a thin layer of sand their maximum temperature 

 was approximately the same in all of them, but the minimum varied 

 somewhat; the sand and gravel would usually be the coldest in the 

 morning followed by clay, loam and peat, respectively. But when their 

 surfect was not covered, this order of the maximum and minimum 

 temperature was just reversed. 



The inequality in average temperature during the spring months, after 

 complete thawing had taken place, and also during the summer months, 

 of the different types of soil when their natural surface was allowed to 

 be exposed to the atmosphere, indicates that there was one intrinsic 

 factor, the heat of evaporation of water, which predominated and caused 

 the variation. The clay and loam, and especially the peat having a 

 greater percentage of water than the sand and gravel, lost more water 

 by evaporation than the latter and consequently their average tempera- 

 ture was kept correspondingly lower. When the surface of all the soils, • 

 however, was covered with the thin layer of sand, the excessive evapora- 

 tion of the clay, loam and peat was reduced and consequently their 



