GALLATIN.

Is twenty-eight miles from Nashville, on the Louisville road. Near the depot stands Fort Thomas, a star redoubt, with six salients built upon a slight elevation. But a short distance beyond is a higher crest, from which the fort is not defiladed. An interior bomb-proof block-house would have made this work quite strong. It is now capable of good defense. Its parapet, however, between five and six feet thick, is rather too slight as against artillery. The ditch is deep and a good obstacle; the scarp and counterscarp are reverted with sods, and the parapet is preserved in the same manner; logs and rails form the breast-height revetment. In each salient is a platform and three embrasures to allow the guns to fire in three directions. These embrasures are not deep, made of logs, and are entirely too open at the throat. The command of the fort is high and the terre-plein is from eight to nine feet below the interior crest. The inclosed space is about equivalent to a square of 200 feet sides. Within the fort is a magazine in fair condition and covered with earth from three to four feet thick. There are also two water-tanks. At the entrance way is a draw bridge which is covered by a redan-shaped traverse. The fort is kept in very good order by the First Ohio Battery, who garrison it. Their barracks are near, between the work and the railroad. Fort Thomas will doubtless be held and there will be no expenditures of any amount connected with its preservation.

DALTON.

Is situated upon the Atlanta railroad, thirty-eight miles from Chattanooga. I have not inspected this fort. Its defenses, as described to me, are two redoubts, one about 300 feet by 120, the other 110 by 120, neither, however, being a regular polygon. The works are very simple, with ditches of medium strength, and substantial parapets reverted. There are no interior keeps or traverses, and but poor magazines. These redoubts will doubtless be retained, and a light battery be mounted within them. Dalton, though in the State of Georgia, like Huntsville and Decatur, is naturally associated with the Department of the Cumberland, and I Have therefore introduced this short description of the place here having omitted it in the report upon the fortifications of Chattanooga.

BLOCK-HOUSES.

The road between Nashville and Gallatin and beyond, to the State line, is well defended by block-houses and stockades. Since December last two additional have been commenced, the material being now ready for setting up the structures. The block-houses that existed along the railroad from Stevenson to Decatur and thence to Nashville, for the protection of the bridges, with few exceptions were destroyed by the enemy at the time of Hood's invasion. On the retreat of the rebel army their reconstruction was commenced under the direction of Majors Willett and O'Connell, of Colonel Merrill's regiment. Those between Nashville and Columbia are mostly set up, but are not yet finished. Beyond Columbia, toward Pulaski, the material for these constructions is prepared. Little has been done between Pulaski and Decatur. On the road from Stevenson to Decatur some of the block-houses are well advanced; others have progressed no further than the preparation of a portion of the timber required. As the positions selected for most of these block-houses in the river bottoms are unhealthy, and as aa large portion of the country on the railroad line from Stevenson by