SAN FRANCISCO, August 12, 1863.

Lieutenant Colonel R. C. DRUM,

Assistant Adjutant-General, Deapartment of the Pacific:

SIR: I have the honor to acknowledge the receipt of your order of yesteday's date directing the immediate construction of the two batteries on Yerba Buena Island and the one near Tichnor's boat- yard. As explined in my former letter of the 1st instant, I will immediately take steps to follow out our instructions. I have received a letter from Captain McAllister, commanding the U. S . Arsenal at Benicia, inforing me that he ahas the following guns available for the proposed batteries, viz, eighteen 32- pounder guns with barbette carriages; ten 24- pounder guns with barbette carriages; six 24- pounder guns on siege carriages with limbers complete. These guns can be readily moved from point to point. Eighteen 10- pounder rifle guns (doubtless with limbers). I recommend that for the battery or batteries in town the guns with limbers be sused, as it would obviate the necessity of buliding a service magazine in the immediate vicinity of the battery. A proper house not far from the battery can be obtained of sufficient size to store the ammunitin and also the limbers, with sufficeient ammunition in filled can be brought to the battery in a short space of tiem. If but one battery is to be erected in town, m as your letter directs, I recommend the six 24- pounder guns on siege crriages for it. If a second one is to be ordered some of the Parrott guns can be used. This will leave twenty- eight guns for the batteries on Yerba Buaena Island. Presuming that you have made such arrangements as will permit me to occupy the ground selected for the battery near Tichnor's boat- yard, I willa t once form the necessary party and commence the work as soon as practicable. I will probably on Friday next again visit Yerba Buena Island, select the site fort he wharf, make the necessary soundings, &c., and report the results. I shall require $5,000 at once for the commencement of these works, but do not make out a requisition in form, as I do not know the name of the appropriation. In hiring men I shall be governed by the prices paid by the officers in charge of Fort point and Alcatraz.

I have th honor to ve, very respectfully, your obedient servant,

R. S. WILLIAMSON,

Captain, U. S. Engineers.

HEADQUARTERS HUMBOLDT MILITARY DISTRICT,
Fort Hu mboldt, August 12, 1863.

Lieutenant Colonel RICHARD C. DRUM,

Asst. Adjt. General, Department of the Pacific, San Francisco:

COLONEL: Department letter of 4th instant relative to Indian out-break in the county of Trininty was received by mail of this day. on the 30th ultimo the officer commanding at Fort Gaston, Major W. S. R. Taylor, reported to these headuqarters that a rumor had reached him through Indiand channel of the murder of a man and woman on New River, in Trininty County. The information was not deemed very authentic, but as it might be true, a detacment of fifteen men under a noncommissionned officer was forthwith sent to the scene of the reported outrage to inter the dead if found, as also to use all practicable efforts to punish the perpetrators. August 3 Major Taylor reported the return of the detachment. It was found that the woman, Madam Weaver, had been killed and her house burned by Indians. A man also, it was supposed, had been killed, but no trace was found of his body. From