Mr Low on the Currents of Tide of the Pcntland Frith , fyc, 
so much wondered at ; though, in a word, there is nothing so 
very admirable with respect to the formation of such a pheno- 
menon as this : it must necessarily follow in every similar circum- 
stance, and is no more to be wondered at here, than when we 
see, in a quick running river, an eddy formed by a rock or stone, 
in which such whirls are as observable as here, though in minia- 
ture, and have the very same effect on straws, and other light 
bodies which come within their vortices, as the wells of Swona 
have on small boats, & c. 
u So true it is, that the same thing happens in every similar 
circumstance. I believe there is scarce a point among the isles 
where the tide comes near, and runs with rapidity, but this is 
observable in a greater or lesser degree ; but it is particularly so 
at the north point of Stroma, where the Swelchee runs off with 
vast rapidity, and dreadful whirling, though indeed not so regu- 
lar as Swona, but enough to shew that the same cause will pro- 
duce the same effect. 
<c So much for the nature of the wells. The diameter of the 
whirls very much depends upon accident; for, when the wind 
blows hard, they are scarcely observable farther than by an ir- 
regular whirl of the tide. In a dead calm they are clearest ; 
but, in this respect, I was something unlucky. The whole time 
I was on the island the wind was high, so that I could not ob- 
serve the whirls so exactly formed as the boatmen told me they 
are wont ; but the foregoing are the thoughts that were suggest- 
ed to me, upon viewing the situation of the island, the run of 
the different tides ; and the rapidity of their motions ; which, 
whether they are just or not, must be submitted. Further ob- 
servations may be made, which may clear up what is deficient in 
them. 
“ Notwithstanding the many stories we hear told of these 
wells, I have heard of no accident happening in them these 
many years ; and indeed I am afraid their power of swallowing 
up ships, boats, &c. has been a good deal magnified : for, though 
1 believe they might be able to overturn a very small boat, they 
can have no such effect on a ship, as has been often experienced 
by people who have fallen into them, and have indeed been hur 
ried away by the force of the stream ; but this was the greatest 
inconveniency they felt from them.” 
