120 
Proceedings of the Royal Irish Academy. 
through the morass as far as Lough S willy aforesaid," while, *' from 
the causeway of Ellaghe, as far as Lough Foyle aforesaid, is through 
the midst of a morass tending to Lough Swilly as aforesaid." Thus, it 
would appear, at that date, to have presented characteristics identical 
with those which Dockwra describes as distinguishing the channel- 
valleys of Derry twenty years before. The furrow across the neck of 
the Inishowen peninsula might therefore have served as a channel, or 
water-course, insulating Inishowen even later than the closed Derry 
channel. 
]N"ow, bearing these facts in mind, it is exceedingly curious to discover 
that in the Escheatment Maps of Ulster, a. d. 1609, the Foyle and Swilly 
are shown connected by a channel ; and this watercourse runs exactly 
in the direction indicated, for it proceeds from an inlet of Swilly, a 
little north of " Bert Castle," south of "Elowh Castle," and joins the 
Foyle a little north of " Derrie." A second but imperfect channel is 
even shown as connecting the Swilly and Foyle south of Derry; it runs 
from the north side of Kilmakatrem Castle" to the south side of 
" Cargan" (now Carrigan). Aileach would thus have been insulated. 
With this, however, we have nothing to do, nor with the insulation of 
Malin, also marked, corroborative evidence not being readily attainable. 
The establishment of the former existence of one channel suffices to 
prove that Inishowen was really an island within historical times. 
Additional proofs of its insulation may be found in the Irish Annals, 
and confirmation in its ancient political geography. Thus, although 
Inishowen is united, both politically and geographically, with the 
county of Donegal, it was of old disconnected from it in both ways. 
Inishowen formed part of Tyrone, politically, and the connexion be- 
tween them still continues ecclesiastically, as the diocese of Derry 
includes Inishowen, Derry, and Tja^one, taking in both margins of 
the Foyle as of old. Named Eoghan's Island, after Eoghan, son of 
Niali of the Nine Hostages, who was buried there, at Iskyheen, the 
Irish annalists repeatedly and emphatically distinguish it as an island. 
This is observable in the following extracts from the Four Masters : — 
"A. D. 1211. Thomas MacUchtry and the sons of Randal Mac Sorley 
came to Derry, v/ith a fleet of seventy-six ships, and plundered and 
destroyed the town. They passed thence into the island of Eoghan 
(Inishowen), and ravaged the entire island." 
This is clear, but so strong is the modern impression of the penin- 
sular character of Inishowen, that Dr. 0' Donovan, in his translation, 
adds the words (" r^^?^^, peninsula"). However, the Annals give no 
countenance to this alteration, as may also be seen from this passage : — 
" A. D. 1010. Oenghus O'Lappan, lord of Cinel Enda, was slain by 
Cinel Eoghain, of the Island,^' i. e. Inishowen. 
Thus the epithet which distinguishes that portion of the Cinel 
Eoghain from those dwelling east of the Foyle was founded on the fact 
that the insularity of Inishowen was then notorious. The Island" 
* In the map of "The Kingdome of Ireland" (a facsimile of the original) attached 
to I'acata Mibernia the_chaniiuls insulating Maliu and Inishowen are also marked. 
