Mr Low on the Currents of Tide of the Pentland Frith, 61 
down upon Swona, and that reinforced by c c, a part of the 
stream of Hoy sound, which runs south by Hackness in Waes, 
and splits on the back of Swona, one part assisting to form the 
wells on the south side h , while the other forms a small whirl on 
the north end of the island i, the effect of which is very much 
taken off by d , a part of the stream of Switha, which sets down 
on S. Ronaldsha ; but, meeting with resistance there, runs broad 
off, and falls almost parallel to the longside of the Island of 
Swona, and can have no such effect as the stronger current has 
at the other, where it strikes almost at right angles, and finds 
little or nothing to divert it. For, though the united streams 
c c and d might have some influence this way ; yet this is much 
taken off by the course of that stream after union, as also by the 
shape of the island, the point l of which covers the wells and 
forms a pretty large eddy in which they play. 
“ At the tide of ebb ( vide Fig. 2.) the effect will be much the 
same, but in a contrary direction ; for here the main tide a , set- 
ting to the westward, part of it will be drawn by the sounds from 
its true direction a a, and run in that marked h , h , h , straight 
upon the south end of Swona f; but when it comes there, in- 
stead of being inclined toward the eddy, as would naturally be 
the case if nothing hindered, here it feels the indraught of the 
Waes Firth, which rather diverts it from, than turns it towards 
the eddy of Swona. Again, that part of the stream h , which is 
next S. Ronaldsha, being more attracted by the sound between 
it and Swona, and in its passage along the S. Ronaldsha shore 
meeting with the Lother, it springs from thence with vast rapi- 
dity, and proceeds N. W. according to the course of the sound, 
till it meets with the point g of Swona, which in some measure 
alters its direction, as it is at the same time drawn by Pightland 
Firth, but very much increases its rapidity, causing it to run off 
in whirls from this point of the island, in the very same manner 
it did at the other in the former case. This must here also ne- 
cessarily happen, as the stream e is closely held in, as well by 
the draught of the Firth as by the partial current c c, both of 
which hinder it from spreading on that side ; but, meeting with 
no resistance on the side towards the eddy, it finds itself more at 
liberty. However, its acquired force does not allow it to spread 
at once. It therefore spends this force in forming these whirls 
