730 STATE BOARD OF AGRICULTURE. 



The air temperature on February 13 when the lowest temperature was 

 reached, was 3° F. 



While the 6-inch depth of all the different types of soil began to freeze 

 about Dec. 12 and its temperature tended to remain at or near the 

 freezing point, the 12 and 18-inch depths of all these soils did not really 

 begin to freeze until the commencement of February when the extreme 

 cold weather came. The 12-inch depth of the gravel and sand froze Feb- 

 ruary 3, that of loam, clay and peat on February 5, or two days later; 

 while the 18-inch depth of the various soils froze as follows: gravel Feb- 

 ruary 6, sand February 8, clay February 10, loam February 11, that of 

 peat did not completely freeze, its temperature remaining a few tenths 

 of a degree above 32° F. throughout the rest of the winter. 



It is remarkable to note that the temperature of the 12-iuch and as 

 well as that of the 18-inch depths attained its minimum degree prac- 

 tically simultaneously with the 6-inch depths. Yet when this minimum 

 was reached at all three depths the difference or gradient of temperature 

 between the 6 and 18-iuch depths Avas very marked, being in most cases 

 close to 12°F. In other words, when the temperature of the 6-inch depth 

 reached its lowest degree, and it was about 20° F, the corresponding 

 minimum of the 18-inch depth, which occurred on the same day, was 

 about 32 °F, or a gradient of 12°F. 



The temi3erature at the 6-inch depth remained considerably below 32°F 

 from February 4 to 20 and then it rose and tended to stay at about 32°F. 

 When the other two deptlis froze their temperature also tended to re- 

 main at about 32°F. Hence the upper 18-inch layer of the* soil had almost 

 the same temperature and consequently had no gradient. 



The temperature of the entire upper 18-iuch layer remained at the 

 freezing point until thawing began. The first thawing occurred on 

 March 19. At this date the gravel and sand thawed completely down to 

 the 18-inch depth — in a single day — while only the 6-inch depth of the 

 loam and clay thawed on this date and that of the peat did not show any 

 signs of thawing. At the 12 and 18-inch depths only clay commenced 

 to thaw by March 26. The process of thawing, however, was only of 

 short duration as on March 26 the air temperature fell very low and the 

 upper 6-inch depth began to freeze again. On March 31, however, the air 

 temperature went up again and the soil temperature commenced to rise 

 accordingly. On April 1 the 12-inch depth of the loam and the 6-inch 

 depth of the peat began to thaw. The 12-inch depth of the peat did not 

 show signs of thawing until April 15. The temperature of the 18-inch 

 depth of the loam began to rise slightly above 32°F by March 8 — long 

 before the actual thawing at the surface of the various soils had taken 

 place — so that by the time the other two depths had thawed it was by a 

 few degrees higher than that of the 12-inch depth. 



This rising of temperature at the 18-inch depth of the loam before 

 complete thawing had taken place at the above depths is extremely inter- 

 esting and goes to indicate that some heat comes to the surface from 

 the lower and warmer depths of the earth. This fact finds confirmation 

 in all the other soils and especially in peat. The 18-inch depth of the 

 latter did not completely freeze but its temperature remained a few 

 tenths of a degree above 32°F. By the middle of March, however, its 

 temperature began to rise slowly but rather persistently so that by 

 April 1, when the 6-inch depth of this soil commenced to thaw it was 



