1897.] PUBLIC DOCUMENT — No. 33. 51 



temperature " is of course the temperature of the atmosphere 

 as we ordinarily feel it, as the sensible temperature is directly 

 dependent upon the relative humidity of the air, and hence 

 upon the cooling eflect of the evaporation of the surface 

 moisture. 



After a careful comparison of the rainfall records of the 

 ground and the tower, obtained in each case by United States 

 Weather Bureau rain gauge, it was found that the tower 

 records were so affected by upward wind currents, due to 

 the shape of the roof, as to render them of very doubtful 

 value. The tower " precipitation " observations have there- 

 fore been discontinued. 



Some additional records have been kept during the past 

 year and will be continued this year. Among these are the 

 number of days of sleighing and the amount of snow on the 

 ground at the beoinnino- of each week, the latter being re- 

 ported to the New England Weather Bureau weekly. Record 

 has also been kept of the accuracy of the forecasts received 

 daily at this station ; this record shows that, while the monthly 

 percentage of correct forecasts has varied from 69 per cent, to 

 90 per cent, during the year, the mean percentage of accu- 

 racy of forecasts has been 78 per cent. 



A few new instruments have been added to the station's 

 equipment : two sets of Green maximum and minimum ther- 

 mometers ; six mercury thermometers, United States Signal 

 Service pattern, made by Green ; and a thermophone,* with 

 four resistance temperature coils, made by E. S. Ritchie & 

 Sons, the latter instruments being intended for experiments 

 on soil temperatures. 



Through the courtesy of Professor Whitney, one of his 

 assistants, Mr. Thomas H. Means of the Division of Soils, 

 Department of Agriculture, was sent to Amhert^t in the mid- 

 dle of July to install a set of Professor Whitney's apparatus 

 for the determination of soil temperature and moisture. Soil- 

 temperature electrodes and moisture-resistance plates were 

 buried in grass land, a short distance from the ground shel- 

 ter, at five ditferent depths, from the surface of the ground 

 to a depth of two feet; and from that time, the middle of 



* The thermophone was recently designed and patented by Messi's. Henry E. 

 Warren and George C. Whipple. 



