NE of the first questions which the British Cabinet asked of the new American Minister sent to England by Mr. Lincoln was, whether the President was serious in his proclamation of a blockade of all the ports of the States in insurrection. The coast was very extensive, said Lord John Russell, stretching some three thousand miles along the Atlantic and Gulf of Mexico: "Was it the design of the United States to institute an effective blockade in its whole extent, or to make only a declaration to that effect as to the whole, and to confine the actual blockade to particular points?" Mr. Adams replied that he had every May 21, 1861 reason for affirming that the blockade would be made effective; that although the coast line was in reality very long, yet the principal harbors were comparatively few, only some seven to ten in number, and those not very easy of access. It would therefore not require so numerous a fleet to guard them as might appear at first thought.