From Charleston

New York, Dec. 29. A Charleston letter to the Baltimore American, riated on iho fleet, iMih, says : " As I inlimnted in my last, we have puiled down hen-, and with the expectation oi n rnnnth or two more of inaclivity. Tho stiike auiong thu engineers at the íiorth, which has delayyd tho eompletion of tho monitors, and deprived our iron-clad fleet of reinforoements which wero cspected here inore ihan a month niñee, has boen the primury cause of the delav. Tho disaslor to tho Weehawken, and tho coming of the winter suason, wilh its constant storms, hus still furfher enforced this delay. Twó months henoe, spring vi:i bn advaneed horo, and with our iron ciad forcé increased by thrce or fonr nevv monitors, we will be prepared to take advantago oí the mot-t healthful and ploasant part of the season. Let tis hope, il Grant does not steal % niarch on us by one of hi.s fi, rnous rear attaoks that Charleston wül tfcén fall. In tho mean time, if we cannot look for immediato and decisivo ros u lts, no great disaster need be apprehendod. Gen. GürnoreV position is impregnablo, The monitor Lehigh, by the timo tliis reaches yon, will havo ootnpletd her repairs rendered necessary by the nummering while aground. The Palapsco li:is nearly completed her repair8 and will shortly relieve the Nantuoket at War&aw Sound. Both the Patapsco and Lehigh have been pro vided with extra deck plates, that wil add to thcir invulnerabiliiy.