EXPERIMENT STATION BULLETINS. 647 



jieriod. The thawing commenced about the beginning of April. The vari- 

 ous soils and the diflerent depths Avithin the same soil thawed at differ- 

 ent dates. The 6-inch depth of the gravel and sand thawed April 5, of 

 the clay April 6, of the loam April 7 and of the peat April 15. The 

 12-inch of the gravel thawed April 5, of the sand April 6, of the clay 

 April 10, of the loam April 13 and of the peat May 1. The 18-inch depth 

 of the gravel and sand thawed April 7,, of the clay April 12, of the loam 

 April 15. and of the peat April 24. 



Immediately after the commencement of thawing, the temperature of 

 the dilTercnt soils at the G-inch depth began to rise quite rapidly but 

 at different rates. The temperature of both the gravel and sand rose 

 far above that of the other soils, followed by clay, loam, and peat re- 

 spectively. This order of magnitude continued until all the lower 

 depths of the heavier soils thawed, then their temperature rose rapidly 

 and approached that of the lighter soils. The time that it took the 

 heavier soils to attain the same temperature as the lighter soils at the 

 G-inch depth varied with the soil, for the clay it was 11 days (April 

 IG), for the loam 12 days (April 17), and for the peat 32 days (May 

 6), from the date the upper G inches of the gravel and sand began 

 to thaw. From these dates on, the temperature of the upper surface 

 of nil the soils ran about the same. 



The temperature of all the soils at all three depths continued to rise 

 till July when the maximum temperature was attained, and then began 

 to fall. At the depth of 6 inches the highest average temperature for 

 all soils was reached on eTulv 11 with the following magnitude : gravel 

 79.2G°, saud 77.4°, loam 78.86°, clay 76.73°, peat 79.33°. At the depth 

 of 12 inches the highest average temperature was attained for gravel 

 on July 11 with 76.8°, for sand July 10 with 75.16°, for loam July 12 

 with 75.26°, for clay July 11 with 74.73°, and for peat July 12 with 

 75.73°. While at the depth of 18 inches the highest average tempera- 

 ture is shoAVB by gravel and sand on July 12 M'ith 73.36° and 72.2°, re- 

 spectively, by loam July 13 with 71.63°, by clay July 13 with 72.5°, and 

 by peat July 13 with 72.23°. From these dates on, the temperature of 

 all the soils at all three depths fell irregularly but gradually till 

 freezing. 



The data for the second year, or cycle, are not presented here but 

 they are on file and show that as far as they go they confirm the first 

 year's results perfectly. The first freezing, for instance, occurred 

 about the middle of December, and ns in tlie previous year the upper 

 6 inches of all the soils froze about the same time as shown by the fol- 

 lowing dates: Gravel and sand Dec. 12, loam and clay Dec; 13, and 

 peat Dec. 14. All these soils remained frozen at this dei)th until Dec. 

 18th when they all thawed and froze again Dec. 23. The 12-inch depth 

 of the gravel and sand froze Feb. 3, of the clay and loam Feb. 5, and 

 of the peat Feb. 6, while the 18-inch depth of the gravel froze Feb. 6, of 

 the sand Feb. .8, of the loam Feb. 11, of the clay Feb. 10 and of the 

 peat Feb. 23. The lowest average tem])erature that all the different 

 soils reached at the ui)j)er 6-inch dei)th was on Feb. 13, with the fol- 

 lowing results: Gravel 22.43° F., sand 19.60°, loam 23.30°, clay 23.93°, 

 and peat 20.50°. In the spring all these soils thawed in the same order 

 as in the first spring. 



