218 Proceedings, of the Royal Irish Academy, 
manner of an island, comprehending within it twenty acres of ground, 
wherein were the ruins of an old abbay, of a bishopp's house, of two 
churches, and at one of the ends of it an old castle, the river called 
Loughfoile encompassing it all on one side, and a bog most com- 
raonlie wet, and not easilie passable, except in two or three places 
dividing it from the maine land." Thus, in Dockwra's eyes Deny 
presented an insular appearance, although what had been the west chan- 
nel was then a wet marsh. Proceeding still further back we discover 
that some half century before, Derry was distinctly known as an island. 
Thus in Queen Elizabeth's Inquisition, dated Derry, 23rd 'Noy., an. 
1545, mention is made of a certain parcel of land, called the Island 
of Derry. The fact that as this Island of Derry" lost its insular 
character, it also gradually lost the name of island, is a proof that 
when that appellation was given to it the term was truly applicable. 
Captain Portlock's excavations furnish the geological links necessary 
in the chain of evidence. 
The ex-island at Strabane enjoyed its insular character two cen- 
turies ago ; three centuries ago it may be held certain that Derry was 
also an island. Thus there was an island at the head, and another 
island at the foot of the Upper Lough, both of which have since become 
connected with the mainland. The insulation of Derry added another 
to the number of islands already mentioned, so that three hundred 
3^ears ago there were at least seven islands in Upper Lough Foyle ; 
and as the lake was more extensive at that period, some knolls on its 
banks must also have increased the number, by their insulation. 
Next comes the question of the former insulation of Inishowen, the 
great peninsula which lies between Lower Lough Foyle and Lough 
Swilly, its neck being near Derry. The name signifies the Island of 
Eoghan, but so firmly is its peninsular character established that no 
idea of its insulation, within historical times, appears to have been 
conceived. People have preferred to do violence to the name or to 
its aptness, regarding it as loosely applied, or only employed for 
want of a more appropriate Irish word, which, however, exists. 
Nevertheless, I am bound to declare that it was once, within his- 
torical times, a perfectly accurate appellation. 
Having satisfied myself as to the former existence and extent of 
Upper Lough Foyle, and noted the various elevations of the soil 
where once its waters flowed, I examined its vicinity for traces of 
contemporary changes. It seemed not improbable that there had 
existed also other features in the landscape, since obliterated like- 
wise. My attention was immediately arrested by a remarkable im- 
pression, or furrow, so to say, which runs from an inlet of the Swilly, 
a little north of Burt House, past Dunberry Hill, between Elagh and 
the Grianan to the Foyle, at Penny burn, near Culmore, a little north 
* This swamp is marked in Neville's Map of the Siege, 1689. A stream ran 
through it, northwards, into a slob, which, occupying all the space known now as 
*' Waterloo Place," extended to the " Cowards' Bastion" and " Corn-Market." The 
slob also bounded " Water Bastion," so that Foyle street now partially covers its 
site on the southern side. 
