264 Rotary Action of the Provident? ‘or 
crossing the river into the State of Massachusetts, it passed 
through Seekonk, Rehoboth, Swansey, Somerset, and as far, at 
least, as Freetown, beyond Taunton river; a distance of twenty 
five miles from the point first mentioned. 
~The width of its visible track, as indicated by the prostration 
of trees, fences, and other objects, varied from a mere trace in 
its narrowest, to two hundred yards or upwards in its widest 
portions. Having, a.few days after the occurrence of the tor- 
nado, carefully examined the track for the distance of about 
seven miles, on each side of Providence river, I propose to offer 
some of the results of this examination, together with such re- 
marks as may seem justly deducible from the effects observed. 
So far, however, as the impressions made on an accidental 
eye-witness of the tornado may be important, we have a valua- 
ble account furnished us in the letter of Zachariah Allen, Esq, 
of Providence, which is given in Dr. Hare’s notice of this tor- 
nado. [This Journal, Vol. xxxvm, p. 74-77.] Mr. Allen had 
the advantage of viewing its progress from a point near its path. 
He calls it a “ whirlwind,” and describes its phenomena in @ 
manner perfectly consistent with this appellation. “The circle 
formed by the tornado” on tke river, he describes as “about 
three vette feet in diameter,” and mentions, that the “misty 
vapors” .. . “entering the whirling vortex, at times veiled from 
sight the center of the circle, and the lower extremity of the 
overhanging cone of dark vapor:” and that ‘“ Amid all the agita- 
tion of the water and the air about it, this cone continued un- 
broken,” &c. 
This “cone” of the tornado of which he so often speaks, it 
should be noted was an inverted one, the smaller end of which 
Was sweeping on the earth’s surface.* 'Thus he gives the in- 
Stance, “when the point of the dark cone of cloud passed over 
prostrate wreck of the building, the fragments seemed to be 
upheaved,” &c. It will be seen here that the prostration of the 
heliinng had preceded the arrival of the center or “ point” of the 
* We may may properly conceive of this “ cone,” in tornadoes or water-spouts, 25 
cling oe the visible clouded condensation here described, but also the 
