2,300, 2,400, and 2,500 yards. Twenty 10-inch guns of the new pattern, firing at 1 1/2 miles with solid shot, constantly at one part of this old work of very poor masonry, may possibly shake the walls. Our forces are small in number. It is absolutely necessary that naval steamers assist us here, otherwise the island may be seized at any time and the siege commenced. The enemy has large quantities of shells and mortars. Whether it will be his policy to besiege us or to try to crush us with curvated fire, and by heavy guns and rifled cannon to knock down a portion of our work, I cannot foresee. The serious obstacle to such means on his part will be the great expenditure of powder. Navy ships, with their large crews, of course would be a great security and assistance to us. Gunboats are wanted if the position opposite is to be attacked. The late unfortunate affair at the head of the Mississippi Passes will call away the Niagara and leave the Colorado here for the present.

I have given Captain Kurtz a description of the night attack made by the secession forces upon Wilson's camp on the night of the 8th and 9th October. I have no doubt that the enemy were much disappointed with the results. The Zouaves [excepting the pickets] proved of little account. They are badly commanded. If incorporated with the regulars they might be made effective. Contrary to the reports in the Southern papers, the enemy did not spike one gun or bourn a store-house. They destroyed about three-fourths of the tents of five companies of Zouaves and robbed some of the officers' trunks. They ought to have been more severely punished for coming with 1,000 men within a mile of our work, but in the confusion of a night attack matters do not always get on well.

Very respectfully, your obedient servant,

Z. B. TOWER,

Major of Engineers.

Bvt. Brigadier General JOSEPH G. TOTTEN,

Chief Engineer, Washington, D. C.

No. 3. Reports of Major Lewis G. Arnold, First U. S. Artillery.

FORT PICKENS, FLA., October 10, 1861.

SIR: In accordance with the directions of the colonel commanding, I have the honor to report the operations of the troops under my command which yesterday aided in driving the rebel force of not less than 1,000 men, under command of Brigadier General Richard H. Anderson, discomfited and in confusion, from the island of Santa Rosa.

I was ordered by the colonel commanding, at 5 o'clock a.m., October 9, to take command of two companies of regulars, Captain Robertson, Company H, Second Artillery, and Lieutenant Shipley, commanding Company C, Third Infantry, and support Major Vogdes, First Artillery, in command of two companies of regulars; Captain Hildt, Company E, Third Infantry; Lieutenant Taylor and 30 men of Company A, First Artillery, and Captain Dobie, Company G, New York volunteers, who had preceded me along the north beach of the island about an hour, with the purpose of attacking in flank the rebels, who had made an attack on Camp Brown, three-quarters of a mile from the fort. Having formed my command very promptly, owing to the efficiency and zeal of the company commanders, I rapidly marched up the beach