The Cumberland Mountains, dividing Virginia from Kentucky, and extending farther southwest to separate East from Middle Tennessee, are the main watershed between the upper waters and sources of the two great rivers. This range is an elevated plateau rising about a thousand feet above the neighboring country and two thousand feet above the sea, the flat top being in some parts fifty miles across. On both sides the cliffs are precipitous, being much notched on the western declivities. Pioneer hunters coming out of Virginia discovered these mountains and the river in 1748, giving them the name of the Duke of Cumberland, the hero of Culloden, then the prominent military leader of England. These explorers came through the remarkable notch cut part way down in the range on the Kentucky-Tennessee boundary, just at the western extremity of Virginia,--the Cumberland Gap. This cleft, five hundred feet deep, is in some places only wide enough for a road, and extends for six miles through the ridge. It was for over a century the highway from southwestern Virginia into East Tennessee and southeastern Kentucky, being previously the trail followed by the Cherokees and other Indians in their movements east and west of the mountains. Through it came Daniel Boone and his companions from North Carolina into Kentucky, and the pass naturally became a great battleground of the Civil War. It is now utilized as the route for a branch of the Southern Railway from East Tennessee into Kentucky, traversing the Gap at about sixteen hundred feet elevation. In one place this road passes through a tunnel of over a half-mile, beginning in Tennessee, going under the corner of Virginia, and coming out in Kentucky. Iron is in abundance all about the Gap. During the war it was fortified by the Confederates, but in June, 1862, they were compelled to abandon it, and the Union troops took possession, being in turn forced out the following September. In September, 1863, the Union armies besieged and captured it, holding the Gap till the end of the war. The great curiosity of Cumberland Gap was the Pinnacle Rock, overhanging the narrow pass in a commanding position. This huge rock, weighing hundreds of tons, fell on Christmas night, 1899, awakening the village at the Gap as if by an earthquake, though no one was injured. CHATTANOOGA AND ITS BATTLES.