ACCOUNT OF THE LATE THUNDER STORMS. 63 



tinder a continuous sheet of cloud ; some of them were loose ^ 



flocciili, others large well defined masses. By degrees th$y 

 became lost ia the upper stratum; the sky became agai a Second storm^ 

 irery black, and thunder and lightning with rain again pre» 

 vailed. During the process of the storm I heard, (beside 

 the many p f Ah o( rolling thunder) another loud single ex- 

 plosion, which sounded like the hollow report of a. mortar; 



it was preceded hf a very vivid flash of lij<htning. I dwell Twodlssimi 



, , ,: . . , TIP. larkindsof . 



particularly on this circumstance, because I have orten no- thunder. 



ticed during storriis two vc-y dissimilar kinds of thunder. 

 One is a long roll increasing in loudness while it continues; 

 this is supposed by Mr. B. P. Van Mons to be^ caused by 

 combustidn of the two gasses of water*. The other is a 

 loud and sharp explosion of short duration, and often a sin- 

 gle report like that of a cannon; the lightning which pre- 

 cedes this is generally vivid and mischievous, it darts di- 

 rectly towards the Earth, or any other prominent object, 

 as high trees, towers, &c., and is considered by Mr. B. P. 

 Van Mons, as the flying off of electricity from an over- 

 charged cloudf. 1 wish to direct the attention of meteoro- 

 logists to the solutioh of this question. When mischief is 

 done by lightning, is not the thunder which follows the flash 

 generally of this latter kind ? 



The variations in the directiott of the wind below, in Various cur- 

 stormy weather, as well as the contrary directions of the '^"^f^^^gj'^ 

 current above, constitute another curious object of philo- iher. 

 f sophical speculation. Small air balloons might, in this Small air bal- 



case, become useful meteorologicail instruments. I have '"'"'•^?^.''' ™*' 



,. ,. " , , ,, , teorological 



sent up a great many ot tnenai,.ana have generally seen them instrument. 



inoved by several different currents of air. 



Yours &c. 



^JClapton, Hacknetji THOMAS FORSTER. 



i<id Aug. 1811. 



♦ See Journal for'Oct^er, 1809, Vol. XXIV, p. 106. 

 •^The distinction of rain, into' " rain of the decomposition,'''' and ** ra-.n 

 i( the recomposition" of air, by Mr. Van Mons, has induced me to in- 

 <|uire. What is the electric stats of rain with a rising, and whafvfith a 

 falliflg barometer f 



