From Gen. Grant's Army

.New York, Murch 1. Letters from Gen. Grant'a headquurters say that thougb all was quiet in front of Riolimood, active nperationi befofo long aro looked for, ard the utmost vigilance is obserred in our lines. A military railroad has been completed to the posiiion on the left of the Ariny of tho Potomao on Hutcher's Rm, and trains will commeoce running regularlv on it iramediately. On Friday last 190 rebel deserten carne into (hetwo armies of the Potomao and the Jiimes. They report that the Peterebiiígh theatre, fillüd with rebej govennneut atores, has been burned, and this is instanced as adtiitional proof of intantioo to evacúate thut town.