Tay, the longest river in Scotland. From its source in Ben Lui (3708 ft.), a mountain on the borders of Perthshire and Argyllshire, it pursues a mainly north-easterly direction to Logierait, where it curves to the south by east as far as Dunkeld; there its course turns to the south-east to the mouth of the Isla, where it bends towards the south by west to the vicinity of Scone. From this point it makes a sharp descent to the south by east beyond the county town, when it sweeps southeast to near Newburgh in Fifeshire, where it again faces the north-east as far as Broughty Ferry, whence it flows straight eastwards into the North Sea, off Buddon Ness in Forfarshire, after a total run of 117 miles. During the first 1 x miles it is known. as the Fillan and discharges into Loch Dochart. From the lake it emerges as the Dochart (13 m.), which enters Loch Tay at Killin. Flowing through the loch for 142 m., it issues at Kenmore under its proper name of Tay. From hence to the sea its course measures 782 m., from which we may deduct 25 m. as the length of the Firth of Tay (which begins at Cairniepier Ferry), leaving 532 m. as the length of the stream between Kenmore and the mouth of the Earn. Its principal affluents on the right are the Bran, Almond and Earn, and on the left the Lyon, Tummel and Isla. Along with its tributaries, therefore, it drains all Perthshire and portions of Forfarshire and Argyllshire, having a catchment basin of 2400 sq. m. In many parts the current is impetuous, and in flood has occasionally wrought much havoc, certain of the inundations being historically important. Its mean discharge of water every minute is estimated to amount to 273,000 cubic ft., a larger outpour than that of any other stream in the United Kingdom. Vessels make Dundee at all stages of the tide, and the estuary is navigable to Newburgh by vessels of Soo tons, and as far as Perth by ships of 200 tons. The navigation, however, is seriously obstructed by shifting sandbanks. The estuary varies in width from 2 m. at Cairniepier Ferry to fully 3 m. at its mouth. The principal points on the river are Crianlarich on the Fillan (with stations on the West Highland and Callander to Oban railways), Luib and Killin on the Dochart, Kenmore, Aberfeldy, Dunkeld, Birnam, Stanley, Scone, Perth and, on the north shore of the firth, Errol, Dundee, Broughty Ferry and Monifieth, and, on the south shore, Newburgh, Newport and Tayport. It is bridged at Kenmore, Aberfeldy, Logierait, Dunkeld, Caputh and Perth (3). The first railway viaduct across the firth at Dundee was nearly two miles long and had been in use for some eighteen months from the date of its opening in 1877. During the night of the 28th of December 1879, however, while a great gale was at the height of its fury, the passing of a train over the central section gave purchase to the tempest and that portion of the structure was blown down along with the train and the unfortunate travellers. Some 75 to 90 persons are supposed to have perished. The second bridges of somewhat lower height, 2 m. and 73 yds. in length, was erected 60 ft. higher up stream and opened in 1887. The Tay is famous for salmon, the annual catch in the river and estuary being the most. valuable in Scotland. There is a hatchery at Hormontfield, close to Luncarty station, 4 m. N. of Perth, for the artificial breeding of salmon, the fish being liberated from the ponds about the age of three years. In respect of riparian scenery the Tay as a whole is the most beautiful river in Scotland, the stretch between Logierait and Cargill, particularly the reaches above and below Dunkeld, being universally admired.