Rappahannock River this morning forty-five sails of vessels-I mean gun-boats and transports-supposed to be Burnside's fleet. They have not as yet appeared in the river (sundown to-night). I will learn more to-morrow and inform you.

I am, general, your obedient servant,

JOHN S. BRAXTON,

Captain and Assistant Adjutant-General.

The enemy have gone aboard of their boats, but still in lie in the same place.

HEADQUARTERS ARMY OF NORTHERN VIRGINIA,
April 19, 1864.

Honorable SECRETARY OF WAR, Richmond, Va.:

SIR: The letter of Lieutenant-Colonel Sims, of the 21st ultimo, referred to me by you, was received, and I have caused inquiry to be made to ascertain whether the mechanics for whom he asks can be furnished. I am fully aware of the necessity of increasing our means of transportation and am gratified that the subject has been taken in hand by the Government. On a former occasion, when I was inquiring as to the possibility of building cars, &c., I was informed that the machine-shops which had been used for work of that kind were all engaged by the Navy Department. I recommended that the cars should be constructed at those shops if possible as they had greater facilities than any that could now be built, besides having mechanics connected with them who had skill and experience in the business. In an interview with the Secretary of the Navy I understood that he thought the work could be done at those shops. If I am correct in this I hope that it may be undertaken, not only to avoid taking so many be undertaken, not only to avoid taking so many men from service, but because I am satisfied that the work can be better and more expeditiously performed. I have no doubt that, in view of the permanent importance of preserving the strength of the army and the impossibility of doing so without transportation adequate to supply it the Secretary of the Navy will allow the necessary work of building cars, &c.,to have precedence over any work of his Department less urgent and not immediately required, and that he will contribute all in his power to save the withdrawal of men from the field, where they are so much needed. I hope also that the Department will see that every means of obtaining the proper mechanics has been exhausted before calling upon the army for men. I think that the facility of obtaining labor in the army sometimes impairs the efforts of officers superintending Government works to procure it elsewhere, but I am sure that you will require every other means to be fully tried before resorting to our already weakened ranks. In the present instance, if mechanics cannot otherwise be had, they must be sent from he army, as the work to be done is essential to its existence, but I see no necessity for taking al from this army now apparently more menaced than any other. The benefit to be derived from the construction of these cars, &c., will inure to all the armies, as it will relieve some of those on the Southern roads now used to supply us, and I think that if possible a proportionate number of mechanics should be drawn from all.

I have thought proper to bring these suggestions to your attention, with the hope that you may be able to give effect to them to the benefit of the service; but at the same time I will meet the demand