METEOROLOGICAL OBSERVATORY 



OK THK 



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. 28. 



APRIL, 1891 



MONTHLY SUMiVlARY. 



Pressure. In inches. 

 Actual maxinuini reading, . 30.27, lOtii, 9 A. 

 Actual niininuim reading, . . . -28.84, 3d, 9 a. 



Mean reduced to sea level •29.923 



Monthly I'auge, 1.43 



*Air Temperature. In Degrees Fahr. 



Highest, 77. ; 79..') 



Lowest, 27.;18. 



Mean, 49.4; 17.5 



Monthly Range, 51.;61..5 



Highest mean dailj- 64.5; 65.5 



Lowest mean daily, 34.9; 28.8 



Mean maximum, 58. ; 59.5 



Mean minimum, 40.8; 35.6 



Mean daily range, 17.2; 28.9 



Greatest daily range, 32.; 43.5 



Least daily range 5; 8.5 



Butnidity. 



Mean dew point 36.3 



Mean force of vapor, 4083 



Mean relative humidity, 60.1 



Wind. 



Prevailing Directions. 



North West 26 per cent. 



North 18 " " 



South South West 12 " " 



South 12 " " 



Other directions, 32 " " 



Total movement, 5484 m. 



Greatest daily movement, . . . . 297 m., 2Sth 

 Least daily movement 79 in., lOtli 



Mean daily movement, 182.8 m. 



Mean hourly velocity, 7.6 m. 



Maximum pressure per square foot, 141bs.= 

 53 m. per hour, 18th, at 6 P. 



* Precipitation. In inches. 



Total precipitation 1..55; 2.66 



Weather. 

 Mean cloudiness observed, ... 49 per cent. 



Number of clear days, 17 



Number of cloudy days, 8 



Number of fair days, 5 



Total cloudiness recorded by the Sun Ther- 

 mometer, 161 hours or 41 per cent. 

 Number of days on which .01 inch or more 



rain or snow fell 6 



Depth of snow, in inches, on ground at close 

 of month, 



Bright Sunshine. 



Number of Hours recorded, 240^ 



Snoiv, 2 d, 3d, 4th, 7th, 25th. 



Total Fall in inches, 11 



Rain, 3d, 11th, 14th, 1,5th, 18th, 19th, 23d,25th. 



Pros*, • 2l8t. 



A.urora, 8tli. 



Thunder and Lightning, . . . 1.5th, 18th. 



Mean Ozone, 62 per cent. 



Halos. 



Solar 6th, 10th, 14th, 26th. 



Lunar, 19th, 22d, 23d . 



I^unar corona, 16th. 



Gales, of 40 or more miles per hour, 46, N. 3d; 

 53 8.S.W. 18th; 46, N.W., 28th. 



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



