An Army of Observation.
--The Chicago Democrat says that a movement is on foot to call a monster Republican Convention of 100,000 men, to be held at Cincinnati on the 2d of March. The delegates of this Convention are expected to be armed and equipped for any necessary service, and will hold themselves in readiness to go to Washington city on the 4th of March, or in any other direction where Generals Scott and Wool may order them to move.