BULLETIN No. 271. 



JULY, 1911 



Meteorological Observations 



AT THE 



MASSACHUSETTS 



AGRICULTURAL EXPERIMENT 



STATION. 



Latitude, 42" 23' 48.5" N. Longitude 72° 31' 10" W. 



Height of barometer above ground, 31 ft. Above sea level, 2'jj.^ ft. 

 Height of Wind Instruments 72 ft. 



MONTHLY SUMMARY. 



Pressure. In inches. 



Maxiiiuiin reduced to freezing, 29 gS, tSth, 8 A. 

 Mininiuin reduced to freezing, 29.24, 24th, 6 p. 

 Reducedt maximum reading, 30.26; 8th, 8 A.; 



27th, 8 A. 

 Reducedt minimum reading, 29.52, 24th, 6 p. 



Mean semi-daily reduced, 29.9S9 



Montlily range, 0.74 



*Air Temperatvire. In Degrees Fahr. 



Highest, 104.0, 4th, 3:30 p. 



Lowest, 490. 26th, 5 A.; 



27th, 5 A. 



Mean iiourly, 73-7 



Mean of means of max. and min., .... 74.6 



Mean sensible (wet bulb), 66.0 



Monthly range 55-o 



Highest mean daily 87.0,. 4th 



Lowest mean daily, 60.4, 28th 



Mean maximum, 87. 8 



Mean minimum, 61.5 



Mean daily range, 26-3 



Greatest daily range, 38-0, ist 



Least daily range, 4-o. 2Sth 



Humidity. 



.Mean dew point 61.7 



Mean force of vapor 825 



Mean relative humidity, 70-7 



Precipitation. In inches. 



Total precipitation, 4-2i 



Number of days on which .01 inch or more 



rain fell. • 9 



•Temperature in ground shelter. 

 t Reduced to freezing and sea-level. 



Wind. 



Total movement, 3878m 



Greatest daily movement, .... 259 m., 24th 



Least daily movement, 33ni., 27th 



Mean daily movement 125.0m 



Mean hourly velocity, 5.2m 



Ma.ximum pressure per square foot, 7.5 ibs.= 



39m. per hour, 5th, 6 P., S. 



Maximum velocity for 5 minutes, 30m. per 

 hour, 5th, 5P., S. 



Prevailing Direction, West Southwest. 



Summary. 



South 23 percent. 



West 19 " 



South Southwest 16 " 



Southwest 10 " 



West Southwest 10 " 



Other directions 22 " 



Weather. 



Mean cloudiness observed, .... 42 per cent. 

 Total cloudiness recorded by the Sun Ther- 

 mometer, 165 hrs. =36 per cent. 



Number of clear days, 9 



Number of fair days, 15 



Number of cloudy days 7 



Bright Sunshine. 



Number of hours recorded, . . 297 hrs. =64* 



Rain, 5th, 6th, 14th, 15th, 17th, iSth, 



20th, 22d, ■24th, 26th, 2Sth, 30th. 



Thunder and Lightning, 5th, 6th, 14th, 



15th, 24th. 



Hail, 5th. 



Gales, 35 or more miles per hour : 39 m , 



5th, S. 



