Tho Washington correspondent of the New Yoi k Express writes: "The liadicals are taking courage frons the folly of tl, e Soutliern ultrat-1, and now begin to talk openly of a permanent exclusión of the Soutb inm f 11 participaron in the governrnent of the country. This is tho plan of Thac'. Stevens and thoso who ' troop under hm dirty tíag.' Uuless the President sha 1 provo as firm as a rock, there is great danger that all our efforts for the preservation of the Union will have been in vain. Thu8 íar ho has behaved admirably. It remaiDS to be neen how he nill conduct himself ' undor fire ' - with the baüeries of New Englaud in full blast against Lis devoted head. In conversation he does uot hesitate to express his uriqualified condemnation of the Northern Radicáis. TJpon this you may rely. If his public policy shall square then with his private sentiments, all will yet be well."