All the staff attended with General McD. Lieutenant Whittemore, ordnance officer, reported for duty.

March 26.-The weather still holds good. General McD. went to headquarters about 11 o'clock, and from there to Washington. A number of horses were sent to Arlington to be shod. Mains got back from Washington with a new horse for Captain Breck. General Orders, Numbers 2, from these headquarters, were printed and circulated to the divisions in the corps. Heard the troops were being embarked as rapidly as possible. Captain Breck took a ride in the afternoon; was gone about an hour and a half. Lieutenant Drouillard and Whittemore went to town; also Doctor Magruder and Captain Barstow went to Alexandria to see about flags, &c.

March 27.-A beautiful spring day. Invitations were sent out early this morning to all the brigadiers of the corps to lunch with the general commanding and Lord Lyons, with a number of officers of the English Guards, at 1 o'clock. A review of Generals Franklin's and King's divisions took place at 2.30 o'clock, and the troops were complimented highly by Lord Lyons and his guests, remarking that some of them were equal to the best of the English army in appearance and drill. The Misses Chase, with Mrs. McDowell, attended the review. After the review the general went to Washington with Mrs. McDowell and guests. A complimentary order was ordered to be issued to the troops to-morrow.

March 28.-The weather still fine. General McDowell returned from Washington about 2 p. m. The general routine of business transacted as usual. A roster of aides-de-camp for daily and weekly duty with the general was made out. General Hatch was transferred, by order from headquarters Army of the Potomac, to General Banks' command.

March 29.-The morning was cloudy and about noon it commenced snowing and continued till dark. General McDowell was here throughout the day. Major Brown and Lieutenant Wadsworth went to Washington. An order from headquarters relieving Colonel Ingalls from duty on this staff was received. An orderly, with wagon, went to town for five reams unruled note paper for printing purposes, and sundry other things. Mail was brought from Washington by Hoagland about 1.30 p. m. for these headquarters.

March 30.-The snow commenced thawing early in the day. It rained occasionally throughout the day. About dark there was quite a thunder shower with vivid lightning. General McD. remained at the office all day. Captain Breck went to Washington in the afternoon. The weekly report was sent in about 6 p. m.

March 31.-This morning it cleared away and the sun came out. General McDowell went to Alexandria about 12 m., in company with General Kearny. Lieutenants Drouillard and Cutting went to Washington in the afternoon. Captain Breck and Lieutenant Wadsworth returned from Washington about 3 p. m.; Major Brown and Lieutenant Cutting in the evening. Captain Sanderson arrived with his baggage, bringing his French cook with him.

April 1.-A very pleasant day. General McDowell went to Washington about 11 a. m. Major Whipple reported by telegraph from Washington for duty. Notice of General Van Rensselaer being relieved from the duty he was assigned was received headquarters Army of the Potomac. General McClellan and staff left Alexandria and went down the Potomac about 5 p. m. Captain Sanderson went to Washington to see about transportation of commissary stores. Captain Breck sent to town for a horse, also for a number of different blank returns.