From Fortress Monroe.
Fortress Monroe July 9
--The steamer Quaker City, some armed freight vessels and several gun boats are preparing to attack Sewell's Point.
A cartridge chest exploded here to-day, killing two Rhode Islanders and wounding a man by the name of Taylor.
Some of the Garibaldians who deserted and went over to the Confederate lines, have returned here.
They have been imprisoned, and the ringleaders will be made examples of.
There is great mortality in several of the New York regiments, which is attributed to excessive drinking.