THE SMITHSONIAN INSTITUTION. 



270 



P. 



Wdd, FranJcUn County , Maine. — Thunder-storm of Septemher 6, 1854. 



OBSERVATIONS. 



Kemarks. 

 a. Thunder very heavy. 



5. Preceded by a gush of rain five seconds before the flashing of the lightning. 

 £. Lightning preceded by gush of rain one second. 

 n. Extremely heavy thunder. 

 '. Liglitning vivid ; thunder extremely hea\y and loud, causing the ground to tremble. 



SUMMAKY EECAPITULATION. 



1. Peals of thunder 'preceded hy visible lightning. 



Average duration of interval between the flashing of the lightning 

 and the first audibility of the thunder, in one hundred and seventy-five 



(175) cases observed 12.32 seconds. 



Minimum ditto (-—I and w&^" — M) 1.00 " 



Maximumditto (a — N) 50.00 '' 



Average duration of interval between the flashing of the lightning 

 and the last audibility of the thunder, in one hundred and forty-eight 



(148) cases observed 34.70 seconds. 



Minimum ditto (o' — M) 5.00 " 



Maximum ditto (<? — L) 86.00 '• 



Average duration of the interval between the first audibility of 

 the thunder, and the last audibility of the same, or the length 

 of the peals, in the one hundred and forty-eight (148) cases ob- 

 served 21.85 seconds. 



Minimum ditto (o' — M and j- — N ) 2.00 " 



Maximumditto (£ — C) 56.00 " 



2. Peals of thunder not preceded hy visible lightning. 



Average duration of the interval between the first and last audi- 

 bility of the thunder, or the entire lengths of the peals, in one 



liundred and fifty-six (156) cases observed 26.60 seconds. 



Minimum ditto (r — Landa— 0) 4.00 " 



Maximumditto (^— J) 80.00 " 



