The fog was so dense upon the river that we could not see the country about the river where they crossed.

W. W. ROWLEY,

First Lieutenant Twenty-eight N. Y. Vols., and Actg. Sig. Officer.

W. W. ROE,

First Lieutenant Sixteenth Mich. Vos., and Actg. Sig. Officer.

First Lieutenant Sixteenth Mich. Vols., and Actg. Sig. Officer.

Signal communications received October 12, 1862, and relating to movements of rebel forces within the lines of the Army of the Potomac.

SUGAR LOAF, October 12, 1862-4.30 a. m.

Numbers 1. All quiet.

Lieutenant CAREY.

SUGAR LOAF, October 12, 1862.

Numbers 2. It is reported that the rebels have crossed. We can see heavy bodies of troops near Hyattstown.

Lieutenant CAREY.

ELK MOUNTAIN, October 12, 1862-7.45 a. m.

Numbers 3. As yet no sign of enemy visible.

Lieutenant OWEN.

CATOCTIN RIDGE, October 12, [1862]- 9. 30 a. m.

Numbers 4. Reports of cannon heard in the direction of Sugar Loaf Mountain.

Lieutenant WIGGINS.

SUGAR LOAF, October 12, [1862]-9.45 a. m.

Numbers 5. The rebels have opened a battery between the month of the Monocacy and Poolesville, a little west of south. One battery is replying.

Lieutenant CAREY.

FARVIEW, October 12, 1862-10 a. m.

Numbers 6. No unusual quantity of smoke a Chambersburg this a. m. can see a force approaching on the turnpike from Hancock, with train of 10 wagons. No enemy in sight. All quiet.

Lieutenant ROWLEY.

SUGAR LOAF, October 12, 1862-11 a. m.

Numbers 7. All that were reported were cavalry, with gray uniforms.

Lieutenant CAREY.

SUGAR LOAF, October 12, 1862-11.10 a. m.

Numbers 8. The enemy crossed at south side of Monocacy, and opened a battery. One battery is replying.

Lieutenant CAREY.

SUGAR LOAF, October 12, 1862-12.15 p. m.

Numbers 9. There is at least one regiment of the enemy's cavalry on this bank of the Potomac, and they are now recrossing that river at about 2 miles the other side of the Monocacy.

Lieutenant CAREY.