I. Introduction. A well-defined group of fells lies somewhat to the east of the main mass of the Lake District mountains, and is centred around High Street. From this wide, lofty, and steep-sided plateau prominent ridges run outwards in all directions. But slightly lower than High Street itself, these rise to such heights as Harter Fell, Ill Bell, Froswick, and others, over 2000 feet above sea-level. The drainage of the area is determined by a main watershed which extends from Kirkstone Pass over Caudale Moor and High Street, descending to Nan Bield Pass, and thence eastwards over Harter Fell, Tarn Crag, and Great Yarlside to Shap Fells. Northwards from this line flow a series of streams which eventually unite to form the River Eden. Of the southward flowing streams, the three most important are the Sprint, Kent, and Trout Beck. The Sprint rises in the peat-covered country under Harter Fell, and flows in a remarkably straight course south-south-eastwards down Long Sleddale to Garnett Bridge, where it turns south-westwards and joins the Kent at Burneside. The Kent rises in the crags south of High Street, and flows down the Kentmere valley in a somewhat irregular course southwards to Staveley; thence through Kendal to Morecambe Bay, into which it falls at Arnside. The Trout Beck rises in Threshthwaite Mouth, a high gap leading into Patterdale, and flows south-south-westwards to Windermere. The waters of the main stream are on the way augmented by Sad Gill, Woundale Beck, and Hagg Gill. The lower reaches