...dly with their work at Fort Harris. One gun has already been mounted, and the remainder will be placed in position to-day — after which they will be engaged in a similar service elsewhere under Gen. Pillow . The Coahoma Invincible, from Friar's Point, Miss., reached the city last night, on the fast steamer Mary E. Keene. They are a fine looking military corps, and are to rendezvous at Corinth, M...