From Gallitzin, the low-grade line delves far south to Hollidaysburgh and then follows the tracks of a former branch line up to Petersburg on the main line, which it parallels to the Susquehanna. Where the main line crosses the Susquehanna at Rockville, the low-grade freight route diverges once again and follows the west bank of the river for a number of miles, completely avoiding in that way Harrisburg and the steel-making towns to the south of it with all of their conditions of congestion. The freight route crosses the broad Susquehanna at Shock's Mills, eight miles north of Columbia, and follows the east bank of the river for twenty miles to Shenks Ferry, where it turns abruptly eastward through the rugged hills of Lancaster County to a connection with the main line at Parkesburg. From thence it follows the main line nearly all the way to Glen Loch, crossing and re-crossing it but at all times retaining its nominal grades. At Glen Loch it makes a wide detour around Philadelphia and its suburbs and reaches with a long straight "short cut" over to the main line at Morrisville near Trenton. So much for the location of this great line of reconstruction. In grades and in curvatures it has achieved real triumphs. The great tonnage here is also always east-bound--coal and iron coming to the seaboard. Its grades also are chiefly consequential then to the east-bound movement. To that movement the heavy grades are again at the almost incredible figure of 3-10 of one per cent--some seventeen feet to the mile. That will mean more when it is understood that that figure is equal to the pull that is required of an engine to start a heavy freight train upon an absolutely level track. With such a pull, grades become as nothing, and the Pennsylvania's operating department is enabled to run 75 trains an hour over this low-grade line; hour after hour upon a 15 minutes' interval. Ask a Pennsylvania officer what he would do with such traffic on his old main line to-day, and he will tell you that he would rather resign than tackle the proposition. The same thing is true on the New York Central lines. Like the Pennsylvania, that railroad thought a little time ago that with its four tracks it might move all civilization. Its acquisition of the bankrupt West Shore Railroad in the eighties gave it two extra tracks across New York State that for a long time were carried on the company's books as deadwood. Now they are filled with freight operation and bringing in a healthy return to their owners. The growing land is always catching up to its new railroad facilities, no matter how rapidly they may be constructed. To-morrow? The railroad operator does not like to think of that. He meets to-day and he plans as best he may against that to-morrow. To meet the great unknown he bids the engineers--those who construct and those who reconstruct--to him, and begs that they exercise their best wits to help him to see a little way into the dim and shadowy future.