If Two Such Clouds Arise One On Either Hand It Is Time To Make Haste To Shelter

AS this Observation is of the same Nature with the former, we shall

continue our Remarks. The Reason why it seldom thunders in Winter is,

because the exterior Parts of the Earth are so contracted by the cold

Snow and Ice, that Sulphur cannot perspire in any great Quantities, but

as soon as the Earth begins to be opened by the Sun in the Spring,

something expires in the Month of April which takes Fire. But by the

Heat of the Sun penetrating deeper into the Earth, the Cortex

is more opened in May, and now there is a more copious Expiration of

the fulminating Matter, and whatever was collected and shut up in

Winter, is now released and snatched up in the Air, and thence proceeds

the most frequent Thunders in the Month of May, and chiefly when a

very hot Day or two has gone before. A less Quantity of the same Matter

remains in the upper Cortex of the Earth for the Month of June, but

in the mean Time a Stock arises out of the deeper Bowels of the Earth,

which is attenuated and prepared, so that by the very fervent Heat of

July it is elevated, as it were in heaps, and set on Fire. Hence

Thunder is as frequent in July as in May. And the Heat decreasing

in the succeeding Months, the Exhalation of the fulminating Matter out

of the Earth is more sparing, and thence, also, the thunder is less

frequent, till in October, and the other winter months, the earth is

bound up with us, and hardly expires any more. Hence we see why it very

seldom thunders when the northerly winds blow; for these winds

constringe the earth with their cold, and so hinder the fulminating

matter from bursting forth; and when they are burst forth and floating

in the air, they hinder their effervency. But on the contrary, when the

warm and moist south winds blow, which open every thing, the earth

likewise is opened, and abundance of fulminating matter is expired and

ascends on high, which is there easily inflamed.

AS the flame runs very swiftly, it seems to carry along with it

particles, which it could not so easily set on fire, and when any of

these particles are drawn together, and heated to a certain degree,

they at last take fire, with a sudden and great explosion, and thereby

produce what we call a thunder Clap. Now, though this be only a single

sound, yet it is often heard in the form of a great murmuring noise of

a long continuance; sometimes for thirty or forty seconds, because of

its various repercussions by the clouds and terrestrial obstacles.

Hence it is, that in vales, which are surrounded by mountains of a

different Height, there is a terrible and long continued Bellowing of

thunder Claps. Whereas for one Explosion it has been observed that

there is but one Clap. Yet however if the Flame set Fire to two, three,

or more fulmineous Tracts, each of them at last will end in a Clap, and

thus several Sounds may be heard together, or quickly succeeding one