Colonel Webster, General Grant's chief of staff, an engineer and artillerist, with a quick eye, has selected a line of defence. There is a deep ravine just above Pittsburg Landing, which extends northwest half a mile. There are five heavy siege-guns, three thirty-two-pounders, and two eight-inch howitzers on the top of the bluff by the Landing. They have been standing there a week, but there are no artillerists to man them. Volunteers are called for. Dr. Cornyn, Surgeon of the First Missouri Artillery, offers his services. Artillerists who have lost their guns are collected. Round shot and shell are carried up from the boats. Fugitives who have lost their regiments are put to work. Pork-barrels are rolled up and placed in a line. Men go to work with spades, and throw up a rude embankment. The heavy guns are wheeled into position to sweep the ravine and all the ground beyond. Everything is done quickly. There is no time for delay. Men work as never before. Unless they can check the enemy, all is lost. Energy, activity, determination, endurance, and bravery must be concentrated into this last effort. [Illustration: THE FIGHT AT THE RAVINE. 1 Union batteries. 2 Rebel batteries. 3 Ravine. 4 Gunboats. 5 Transports.] Commencing nearest the river, on the ridge of the ravine, you see two of McAllister's twenty-four-pounders, next four of Captain Stone's ten pounders, then Captain Walker with one twenty-pounder, then Captain Silversparre with four twenty-pounder Parrott guns, which throw rifled projectiles, then two twenty-pound howitzers, which throw grape and canister. Then you come to the road which leads up to Shiloh church. There you see six brass field-pieces; then Captain Richardson's battery of four twenty-pounder Parrott guns; then a six-pounder and two twelve-pound howitzers of Captain Powell's battery; then the siege-guns, under Surgeon Cornyn and Captain Madison; then two ten-pounders, under Lieutenant Edwards, and two more under Lieutenant Timony. There are more guns beyond,--Taylor's, Willard's, and what is left of Schwartz's battery, and Mann's, Dresser's, and Ross's,--about sixty guns in all. The broken regiments are standing or lying down. The line, instead of being four miles long, as it was in the morning, is not more than a mile in length now. The regiments are all mixed up. There are men from a dozen in one, but they can fight notwithstanding that.