54 
BATHYMETRICAL SURVEY OF 
The river-systems, which arise in the most mountainous and 
magnificent regions of Scotland, may be divided into four principal 
branches, viz., the Garry branch (the most northerly), the Tummel 
branch, the Tay branch, and the Earn branch (the most southerly). 
(1) The Garry branch rises on the flanks of Beinn Mholach, Beinn 
Bhoidheach, and Cam Beag an Laoigh, flowing by various streams 
into Loch Garry, thence by the river Garry into the river Tummel at 
Faskally, to the north-west of Pitlochry, receiving the waters of the 
Erochy at Struan, and those of the Tilt at Blair Atholl. 
(2) The Tummel branch rises in the Black Mount, the westernmost 
of the sources of the Tay river-systems, flowing by the river Ba into 
Loch Buidhe, Lochan na Stainge, and Loch Ba, which receives the out- 
flow from Lochan na h-Achlaise, thence flowing into Loch Laidon, 
thence into Loch Eigheach — an expansion of the river Gaur — receiving 
the waters from Lochan Sron Smeur, and then flowing into Loch 
Hannoch, which receives the outflow from Loch Ericht, flowing finally 
into Loch Tummel, thence by the river Tummel into the river Tay at 
Logierait. 
(3) The Tay branch rises on the flanks of Ben Lui (Beinn Laoigh), 
and flows by the river Fillan into Loch Dochart and Loch lubhair, 
thence by the river Dochart into Loch Tay, being joined by the river 
Lochay at Killin just before entering Loch Tay; the outflow from Loch 
Tay is carried into the estuary of the Tay by the river Tay, which is 
joined shortly after leaving Loch Tay by the river Lyon, bearing the 
outflow from Loch Lyon, and further on (at Logierait) the river 
Tummel, bearing the outflow from the Garry and Tummel branches, 
still further on (at Dunkeld) by the river Bran, bearing the outflow 
from Loch Freuchie, still further on (at Cargill) by the river Isla, and 
still further on, shortly before reaching Perth, by the river Almond. 
(4) The Earn branch takes its rise at the heads of Glen Ogle and 
Gleann Ceann Droma, the two streams flowing into the west end of 
Loch Earn, which receives also the waters of the Ample burn, Beich 
burn, the Vorlich, the Tarken, and other smaller streams; the outflow 
from Loch Earn passes at St. Fillans into the river Earn, which receives 
the waters of the Ruchill and Lednock near Comrie, those of the Turret 
bearing the outflow from Loch Turret, near Crieff, and other smaller 
streams as it flows eastward to join the Tay at the head of the estuary. 
Loch Ericht (see Plates XII. and XIII.). — Loch Ericht is a large 
Highland loch situated partly in Perthshire and partly in Inverness- 
shire, at a high elevation among the Grampians. It is one of the wildest 
and most magnificent lochs of Scotland, presenting all along its shores 
scenes of lonely grandeur and sublimity, the mountains rising from the 
water’s edge to great altitudes, their sides scarred by mountain torrents. 
The surface, when measured by the Ordnance Survey officers in 1872, 
