40 PROCEEDINGS OP THE AMERICAN ACADEMY 



in connection with the theory of storms, and its first appearance on 

 hot summer days, its gradual extension, and the motion of its fila- 

 ments as compared with that of lower clouds, deserve careful watching. 

 The rise of the cumuli, or " thunder-head " clouds, should be noted 

 also, and their angular attitude and apparent direction of motion 

 recorded several times. 



Northfield, Mass.: Thinnest high clouds had passed zenith before 

 14.08; black bank of cumuli in N. W. at 14.50; rain about 15.40. 

 Greenfield, Mass.: Clouds gathering rapidly at 14.00; rain at 15.50. 

 Athol, Mass. : Clouds rising in N. and N. W. at 13.00; rain at 16 01 

 Deerfield Centre, N. H. : A little cloud in W. at 14.00; large black 

 cloud in W. at 14.30 ; '■ clouds overhead," 14.55 ; rain at IQ.'IO. Man- 

 chester, N. H. : Clouding up for three hours before rain began at 

 16.22. Tyngsborough, Mass.: Thin cirrus clouds rising iu S. W. and 

 N. W. at 15.00 ; cumulo-stratus low in west at 15.50 ; the cirrus covers 

 eight-tenths of sky at 16.10, and top of cumulo-stratus estimated 20° 

 above horizon ; at 16.30, 60° over horizon ; at 16.37, edge overhead ; 

 at 1 6-39 rain began.* Hartford, Ct. : Western sky hazy at 14.00, tem- 

 perature 93°+, with brisk southerly wind ; a few light cumuli floated 

 rapidly from S. W. to N. E., and a bank of cirro-stratus was seen low 

 in the N. W. ; at 15.15 the bank had risen somewhat, aud cumuli were 

 seen beneath it; at 16.30 cumuli could be seen rising from the cirrus; 

 thunder was then heard and the sun was soon obscured. Clouds were 

 rising in the west, but the storm seemed to be passing from S. W. to 

 N. E. At 17.00 the storm seemed to approach the city, and at 17.23 

 the rain began and the wind veered from S. W. to N., blowing brisk ; 

 later, the wind turned to E. ; plentiful large hail-stones and destructive 

 wmd were reported a few miles east. Coventry, Ct. : Heavy clouds in 

 N. W. at 15.30 ; rain at 17.30. Lynn, Mass. : " Edge of storm over- 

 head" at 16.00 ; rain at 17.30. Chelsea, Mass. : Hazy clouds in W. 

 at 12.30 ; heavy clouds in W. at 16.30; sky half covered at 17.10; rain 

 at 17.32. Swampscott, Mass.: Heavy clouds rising in W. at 15.30 • 

 heavy shower in W. at 16.00; destructive N. W. squall at 17 25; rain 



* By means of these observations of altitude, it is possible to determine the 

 height of tlie clouds, when the velocity of the storm's progress is known. In 

 this case, the velocity was about forty-eight miles an hour for this part of the 

 storm; and a simple construction then gives the heights as about eight and 

 nine miles, at the times of the two observations. These, however, are not even 

 in spite of their good agreement, sufficiently accurate or certain to base much 

 argument upon; but they serve well to sliow how easily observations may be 

 made that will lead to most interesting results. 



