METEOROLOGICAL OBSERVATORY 



Hatch Experiment Station, 



MASSACHUSETTS AGRICULTURAL COLLEGE 



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



Height of instruments above ground, 51 ft. Above sea level, 260 ft. 



BULLETIN No. 31. 



JULY, 1891 



MONTHLY SUMMARY. 



Pressure. In inches. 

 Actual maxinium reading, . 30.00, 22(\, 7 a. 

 Actual minimum reading, . . 29.35, 8th, 1 A- 



Mean reduced to sea level, 29.980 



Monthlj' range, 74 . 



*Air Temperature. In Degrees Fahr. 



Highest, 86; 90 



Lowest, 51; 41.5 



Mean, 68.2; 66.3 



Monthly Range, 35 ;4S.5. 



Highest mean daily, 76.3; 76.5 



Lowest mean daily, 62.6; .57.3 



Mean maximum, 76.2; 78.4 



Mean minimum, 60.1 ; .54.2 



Mean daily range, 16.1; 24.2 



Greatest daily range, 30. ; 37.5 



Least daily range, 8; 12.5 



Humidity. 



Mean dew point .58.5 



Mean force of vapor, 7778 



Mean relative humidity, 66.1 



Wind. 

 Prevailing Directions. 



South, 15 per cent. 



North, 14 " " 



South South West, 13 " 



South West 13 " 



Other directions, 45 " " 



Total movement, 3907 m. 



Greatest daily movement, . .234 m., 6tli, 1.5th 



Least daily movement, 41m., 17tli 



Mean daily movement, 126 m. 



Mean hourly velocity, 5.3 m. 



Maximum pressure per square foot, 4^11)8.= 

 30 m. per hour, 31st, at 10 A. 



* Precipitation. In inches. 



Total precipitation, 4.93; 5.28 



Weather. 

 Mean clouiliness observed, . . . 54 per cent. 



Number of clear days, H 



Number of cloudy days, 10 



Number of fair days, K' 



Total cloudiness recoi'ded by the Sun Ther- 

 mometer, 240\ hours or 52 per cent. 

 Number of days on which .01 inch or more 

 rain fell, 9 



liright Sunshine. 



Number of Hours recorded, 222i 



liain, 2d, 4th, .5th, 6th, 7th, 9th, 15th, 18th, 



24th, 25th, 28th, 29th, 30th. 

 Thunder and TAghtning, 4th, 1.5th, 20th, 



24th, 2.5th. 



Itainbout, 4th. 



Mean Ozone, 40 per cent. 



TTnlos. 



Solar, 8th, 0th, 12th. 18th, 19th, 20th. 



Lunar, 10th. 



dales, ot 30 or more miles per hour, 30, N. 

 3lRt; 



♦The first figures denote readings at top of tower, the secoml at base. 



