EXPERIMENT STATION REPORT. 565 



MR. THAYER'S NOTES. 



Mr. Henry J. Thayer, of Boston, Mass., proprietor of the Indian 

 Head cranberry bogs at Plymouth, Mass., was present at the Cran- 

 berry meeting in January, and he was good enough to supply me 

 w^ith a series of temperature obsei-vations made on his bogs, from 

 which he drew the following conclusions : 



First. That the fierce heat of the sun is (almost) entirely dissi- 

 pated within two or three inches of the surface of the water and 

 greatly diminished at even one inch. 



Second. Between depths of four inches and twenty inches the tem- 

 perature of the water is (practically) the same, and shaded portions 

 do not differ materially from those exposed to direct sunlight. 



Third. Below twenty inches the direct heat of the sun is lost, and 

 rise and fall of temperature corresponds to the seasonal change in the 

 warmth of the earth. 



Fourth. A daily rise in temperature occurs within twenty inches 

 of the surface, whether the day is cool or hot, clear or cloudy, and the 

 daily range is nearly as great on an ordinary cloudy day as under a 

 clear sky and hot sun. 



Fifth. Even under an ice covering a daily change in temperature 

 occurs. 



Sixth. Sharp extremes of day and night temperatures somewhat 

 affect the following daily record, but not to any very great extent, and 

 the changes that do occur are more in the nature of a seasonal than of a 

 daily or weekly change. 



In a general way, these conclusions have been borne out by the 

 records received. At from three to four feet there was a constant in- 

 crease of temperature from a minimum of 46° on April 19th, to a 

 maximum of 64° on May 10th, though the outdoor temperature 

 ranged in the same period from 23° to 84.5°. Many things had to be 

 considered in making the records and in drawing conclusions from 

 those that were made, for no two bogs are alike in exposure, in the 

 source of the water-supply and in the amount of flow in the water- 

 body. The effort was to get at conditions as they existed in a 

 practically permanent water-body without a definite channel or cur- 

 rent through it. The larger the body of water the more uniform its 

 temperature ; and where the supply io keep up the head came from- a 

 reservoir or large storage area, it was more uniform than where it was 



