IRELAND. 



391 



and Slieve Nakilla on the south, and which flows into the head of Lough Allen, 

 is the real head-stream of the Shannon, but popular tradition looks upon the 

 Shannon Pot as the veritable source. This is a copious fountain rising in a lime- 

 stone caldron, and fed by a subterranean channel which connects it with a louffh 

 at the base of Tiltibane. Scarcely formed, the river is lost in Lough Allen 



Fig. 197- — Upper Lot'GH Erxe. 

 Scale 1 : 200,000. 



7°|30' W.of Gr. 



_ 2 Miles. 



(160 feet above the sea), and thence to its mouth, for a distance of 209 miles, 

 the Shannon is navigable. On issuing from Lough Allen the river flows 

 sluggishly for 80 miles over the central plain, passing through Lough Eee 

 (122 feet) and Lough Derg (108 feet), when it enters the gorge of Killaloe, 

 separating Slieve Bernagh from Slieve Arra, and with a rapid fall reaches 

 Limerick, where it becomes a tidal river. We may fairly ask how it happens 



