Colonel James H. Simpson, Corps of Engineers, for the Western armies, and that at New York for the general service, in charge of Mr. W. P. Trowbridge, engineer agent, who has also met all the calls for material, apparatus, & c., of the officers engaged in the construction of our permanent fortifications.

From among the reports from officers of the Corps of Engineers with the armies in the field I have selected five of particular interest that may be published at this time without prejudice to the public interest. They are -

First. On the use of india-rubber pontoon bridges by the army under General Steele.*

Second. Passage of the James River by the army under General Grant on a pontoon bridge.+

Third. Siege of Fort Morgan by the army under General Canby.#

Fourth. Siege of Fort Gaines by the army under General Canby.&

Fifth. Description of the mine made under the enemy's works at Petersburg by the army under General Grant.@

The journal of the siege of Forts Wagner and Gregg and the demolition of Fort Sumter will not be received in time to accompany this report.

* * * * * * *

Pontoon bridge - Passage of James River by the army under General Grant.

HEADQUARTERS ENGINEER BRIGADE.

Camp at City Point, Va., June 24, 1864.

General R. DELAFIELD,
Chief of Engineers:

SIR: I have the honor to report, as you will see by the inclosed copy of note from Lieutenant Carroll, at the engineer depot, that the two wooden pontoons which you desired to have made according to my proposed modification are now complete at the depot and appear to be very satisfactory indeed.

Should you have the time I shall hope that you will be able to examine them soon, and if they please you that you will order all wooden pontoons in the future to be built of that model. It is barely possible I have thought that it may be expedient to set the hooks for lashings some three inches more toward the stern to insure somewhat greater buoyancy at the bow.

I presume you will be pleased to hear of the success of our pontoon bridge, over 2,000 feet long, over the James River just above Fort Powhatan, which I had placed there on the evening of the 15th instant by the troops under Captain Mendell and Lieutenant Gillespie, of our corps, about 200 men, and two companies of the Fifteenth New York Volunteer Engineers, under Captains Lubey and Henderson, and a fractional company of the Fiftieth New York Engineers, under Captain Robbins, 250 volunteers, or, in all, 450 men.

On the 13th and 14th, in accordance with an order of General Grant, I had sent up the pontoon rafts from Fort Monroe under the above-named volunteer troops, not feeling then at liberty from the previous orders of General Meade to leave my other property and troops to go up myself. But about 11 a. m. on the 15th I received the order, and was under way in half an hour, arriving at the position selected at about 5 p. m. There I found General Meade and General Weitzel, which latter had prepared the approaches and had the abutment commenced. I was at once directly charged with the laying of the bridge by General Meade, with the regulars to assist the volunteers, and he smiled when I told him I should not sleep till the bridge was laid.

I distributed my men at once, the regulars at the east end, the volunteers at the west end, and a company of volunteers to prepare a part or raft by my plan of simultaneous bays.

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* Extract from Steele's report, Series I, Vol. XXXIV, Part I, p. 670, beginning "The enemy having disappeared" and ending "to operate on Current and Black Rivers."

+ Follows.

# See Series I, Vol. XXXIX, Part I, p. 411.

& Ibid., p. 408.

@ See Series I, Vol. XL, Part I, p. 556.

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