COLUMBUS, KY., October 24, 1863.

Colonel J. K. MILLS,

Commanding, Union City:

You will send out all the cavalry you have, except the pickets now on outpost, under a judicious officer, in the direction of Boydsville, to get in the rear of the rebels, and follow them up if they have passed into Kentucky or are lurking near the line. I send you to-day two companies of cavalry to do picket duty at Union City during the absence of your cavalry. Send out with the command several good scouts to keep you constantly advised of the movements of your cavalry, as well as that of the rebels. You will give the necessary instructions for carrying out the above order if you regard your information as reliable. Colonel Waring goes out to-day.

A. J. SMITH,

Brigadier-General.

CAMP NELSON, October 24, 1863.

Major-General BURNSIDE:

When you left Kentucky there seemed to be some objections to the proposition to introduce contraband negroes from the South into the State to labor on military roads. Since that time the subject has been thoroughly canvassed, the advantages and disadvantages have all been fully weighed, and, opinion with slave owners in this region that no serious difficulty will arise from using them. I have before me a petition from a large number of slave owners in the counties of Lincoln, Boyle, and Mercer, praying that slaves be immediately taken to improve the State; a sufficient number of them to prosecute the work and military road, and completing at the least possible period.

The great difficulty presented by the opposers of the movement was that slaves in Kentucky would become demoralized and worthless by coming in contact with the contrabands. To prevent this, it is now proposed that the contrabands be placed upon the road south of Danville, and the impressed negroes upon the road between Nicholasville and Danville, thus keeping them entirely separate. I am satisfied that unless something of this sort is done, the work will not progress as rapidly as you and its friends desire. The impressed hands will not amount to more than 2,500; to divide them between the two roads now in process of construction, will not give to each sufficient force to complete the work in any reasonable time, and to impress slaves from the counties upon which the call has been made, would be doing great injustice to the farming interests of the country.

I have consulted with Major Simpson upon the subject, and he gives it as his opinion that it is the only way by which the work can be successfully prosecuted.

Colonel Bowles was here a short time since, and said if this arrangement could be effected, there would be no difficulty in completing the Central Kentucky road between Nicholasville and Danville. Besides all this, there is a great deal of work to be done at a depot, and on the fortifications at this place, and I shall be compelled to keep a portion of the impressed negroes here for a time to complete that