METEOROLOGICAL OBSEHVATOEY 



Hatch Experiment Station, 



MASSACHUSETTS AGRICULTURAL COLLEGE, 



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



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



BULLETIN No. 33. 



SEPTEMBER, 1891 



MONTHLY SUMMARY. 



Pressure. In inches. 

 Actual maximum reading, . .30.16, .SOtli, 12 p. 

 Actual minimum reading, . '29.44, 7tl), Hp.m. 



Mean re<luced to sea level, 30.115 



Monthly range, 72 



*A.ir TetHpcrnture. In Degrees Fahr. 



Highest, 86; 91..5 



Lowest 43 ; 36. 



Mean, 65.3; 64.9 



Monthly Range, 43; 55.5. 



Highest mean daily, 74.2; 75.5 



Lowest mean daily, 55.S; .t2 S 



Mean maximum, 72.4; 76.9 



Mean minimum, .56.8; 52.9 



Mean daily range, 15.6 ; 24. 



Greatest daily range, 27. ; 39. 



Least daily range 5; 11. 



Hitniitlity. 



Mean dew point, 58.1 



Mean force of vapor, 7010 



Mean relative humidity, . 72.1 



Wind. 



Prevailing Directions. 



South South West, 17 per cent. 



North, 13 " 



South Wc.^t, 12 " 



South South East, 11 " 



Other directions 47 " " 



Total movement, 3,.'0l m. 



Gi-eatest daily movement, .... 218 m., 30th 



Least daily movement, 44 m., 2d. 



Mean daily movement, 106.7 m. 



Mean luiurly velocity, 4.5 m. 



Maximum pressure per squai-e foot, 4 lbs.= 

 28 m. per hour, 30th, at 4 P. M. 



* Precipitation.. In inches. 



Total precipitation, 1.78; 2.66 



VTenther. 



Mean cloudiness observed, ... 50 per cent. 



Number of clear days, 18 



Number of cloudy days, "> 



Number of fair days, 5 



Total cloudiness recorded by the Sun Ther 



mometer, 151 hours or 34 per cent. 

 Number of days on which .01 inch or more 



rain fell " 



Bright Sunshine. 



Number of Hours recorded, 224 



Ruin, 1st, 5th, 6th, 13th, 15th, 17th, 21st, 27th, 



29th. 

 Aurora, 9th, 10th, 11th. 

 Thunder and />itf/(fn*/if/, 6tli, ].3th, 26th, 



29th. 



Mean Ozone, 15 per cent. 



Uulos. 



Solar 3d, nth, 1.5th. 



Lunar, Hth. 



*The first figures denote readings at top of tower, the second at base. 



