A steam fire-engine has been furnished to force water from the river to the hospital, for sprinkling the streets and to cool the heated tents. Gen. Grant was walking through the hospital a few days since, and observing how much they suffered from dust, said “his wounded men must be better cared for; the streets must be watered, if it took a regiment of men each day to do it.” As his word is law, the engine came: a large force of negroes have it in charge, and already the good results are seen. Water-tanks were afterward built, more engines and hose obtained, and all day long the street-sprinklers are at work. The dust continues fearfully deep; it is the only thing that moves about freely.

The third division of the sixth corps marched by today, to embark on transports; going North, it is said, to look after Ewell’s corps—that, we hear, is destined for another raid upon Pennsylvania. Numbers of “volunteer aids” have been obliged to give up their work here; many ill with fever; Mr. H. obliged to go home for a few days’ rest, thoroughly worn out with the arduous labors which have occupied him since early in the spring. Each corps hospital has its share of the colored population: our settlement for them is on the river bank; from there we hear their voices as they join in their evening worship; going into their meeting, we found them kneeling upon the earth, praying earnestly that “God would bless good President Lincoln,” and “all do great Union armies;” that “He would take care of de breddern and sisters, now they be in a foreign land;” then, interrupting the prayers, a voice commenced—

“O, praise an’ tanks! Do Lord he come

To set de people free!”

Prayers and their simple music were strangely blended, but all in the most devout manner.

On the 14th of July, a floor was put in our tent; previous to this, the deep dust was the only carpet we had; an arbor of evergreen branches was also placed at the two entrances; now sheltered from the scorching sun, we are very comfortable—quite luxurious living, and certainly we should never complain while sick and wounded lie upon the ground. But, in contrast with this dwelling, sometimes will come before us thoughts of a country home in Pennsylvania, with cool, airy rooms, and pleasant surroundings of shade- and fruit-trees, abundantly-planted gardens, etc., until the longing to be there seems irresistible. The absorbing duty in which we are engaged, is all that can make us forget it.

July 30th. Rebel fort blown up at seven this morning; the cannonading and firing during the night which preceded the explosion were fearfully distinct, so much so as to prevent sleeping. Large numbers of wounded were brought in to-day, principally to the ninth corps and the colored hospital. Among the colored troops, four out of every five of their officers were either killed or wounded; yet the men behaved bravely.

A young lieutenant from the ninth corps called to tell us he had been wounded in the late engagement, and that he had been promoted; with his twin brother, he entered the service at the very commencement of the war; the other, a lieutenant, fell at South Mountain; but —— passed unhurt through numberless battles, until this time; and was determined to remain with his regiment after being wounded, until told by the surgeon that if he did so he would lose his foot, probably his life; very reluctantly he came to the hospital. When his commission was received, his comrades asked him if he was aware that “in their regiment promotion meant death?” and then going over the list of names, such and such a one had been promoted, and soon after fallen, his reply was: “Yes, he knew all that; but should accept it just the same, if he was conscious that death came with it—was perfectly willing to take his chance with the 'boys!’” With him was a frail-looking lad, wounded in the head; the lieutenant found him, after the fight, near the intrenchments, sobbing; as he came near, the boy called that he was wounded, and quickly said: “Will you write to my father, and tell him I did my duty as a good soldier?” “Yes,” was the response; “but first bear your wound as a soldier.” The sobs were instantly stilled, and he went with the lieutenant to the hospital; his elder brothers were in the army, and he had long been anxious to join them; but he was—

“Only a boy! and his father had said

He never could let his youngest go.”