of the city authorities I had erected a one-gun battery (8-inch columbiad sent me on pplication by the chief of ordnance) on a shelf of land projecting from a high bluff bank, the latter rising 150 feet above the water; the battery is about thirty feet above the river. Adjacent to this columbiad, which is mounted en barbette and has excellent range on stretch of the river, I also had constructed an intrenchment for about 300 troops, sixty feet above the water on a prolongtion of the shelf, with platforms for three orfour smaller pieces, if such could be procured. Some 6-pounders (old iron ones) were afterward sent to this place, called Shell Bluff, from marly composition, and an 8-inch siege howityer on its carriage was afterward prepared at the arsenal for this post; but the river getting too low before it was ready, it still remains at the work-shop, ready, however, for use.

Obstructions were also placed in the river near the battery, consisting of a ponderous iron chain supported by as line of rafts, the latter being anchored securely to the bottom of the stream. This work was afterward removed in part to alow steam-boats to pass

after the danger had passed over of an attack by the enemy, since which time, having no one to look after its preservtion, it has been broken loose by the drift-wood and boats, and now no longer exists as an mpediment. The city authorities last June, at my suggestion, took up the matter of the river obstructions (having no time to attend to the matter myself and no officer to place in charge), and sent a committee of gentlemen to determine at what point and in what manner obssdtructions should be erected. This resulted in piling the bed of the river entirely across the stream about eighty miles below the city. My suggestion that such obstructions should be near and under the fire of Shell Bluff was neglected for reasons that I do not now call to mind-perhaps for a greater economy of procuring timber. My time was altogether occupied in my legitimate duties, so that I did not see the work until a short time since. I think a high rise of the river will wash a new channel entirely around one or both flanks of the piling, which will thus incommode or render the passage of a gunboat difficult, but not impracticable. The only reliable defense of the river, the, consists in the high fluffs generally on the Georogia side, commanding the narrow river, which is rarely wider than 300 feet, and from which sharpshooters would have entire control of the channel and the defenses at Shell Bluff. I think the two would be entirely sufficient to defend the navigation of this abruptly winding, narrow stream if garrisoned with troops. Not less than 500 should be at the latter place on ocasion, and about the same number distrbuted along the different bluffs (with rifles) between there and Savannah. A land raid on the Georgia side I think would not be attempted on account of the distance, but one might be made from Port Royal via Pocotaligo to Hamburg. As the Savannah River is nowhere fordable in this section, Augusta could be readily secured from such kind of attack by securing the few ferry-boats available and guarding or cutting the city bridges if timely information was received. Having just been placed in charge of the foundry at Selma, Ala., in addition to retaining my command at this place of the various Government works, it will be out of my power to attend to the military defenses should an emergency arise in the future requiring attention to the defense of the upper Savannah River.

Very respectfully, your obedient servant,

GEO. W. RAINS,

Lieutenant-Colonel, Commanding.