264 Rotary Action of the Providence Tornado. 



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. xxxviii, 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 a 

 manner perfectly consistent with this appellation. " The circle 

 formed by the tornado" on the river, he describes as "about 

 three hundred 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 aj|i tlie 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 

 the prostrate wreck of the building, the fragments seemed to be 

 upheaved," &c. It will be seen here that the prostration of the 

 building had preceded the arrival of the center or " point" of the 



* We may properly conceive of this "cone," in tornadoes or water-spouts, as 

 including not only the visible clouded condensation here described, but also the 

 invisible portion of the whirlwind which surrounds the narrow and depending 

 portion of the visible cone, below the general line of condensation. This entire 

 body of the whirlwind is generally a truncated cone ; its smaller and most active 

 end sweeping along the surface of the earth or sea. 



