There is reason to apprehend that the men who are really true to the Union do not appreciate the extent to which treason is working among us. Worse than all, there are many, who, while believing themselves true to the good cause, are, by constant grumbling and complaint, aiding the very worst form of disunion. Could we prevail with one prayer upon the heart of every Federal freeman, it would be to implore him in this hour of trial not to withold his warmest support from the Administration and to fall into the common weakness of fault-finding and despairing. Such enormous wars as this never have been ended in a few months; wars especially which involve the deepest antagonism of social principles in existence. And our winnings have been neither few nor light. The Southern Border States, with little exception, are now ours, and will inevitably be fully won in time: New Orleans is a pledge, with other important points, and the enemy admit that every Southern seaboard town is destined to be taken. Does this look like the wild boasting of the South two years ago, when the North was to be plundered, Washington taken, and the Free States trampled under the heel of a chivalry fiercely crying, _Væ victis!_'--'Woe to the conquered!'? There is no danger now from the enemy: as he himself admits, two years more of the war would not, at the rate in which we progress, leave him a single State; and be it borne in mind that a _speedy_ return to peace is only to be purchased at the price of a terrible financial crisis. But we are in danger from the traitors _at home_. JEFFERSON DAVIS is less deadly to the Federal Union and less to be dreaded than the men who are scheming to make of New York a free city, and of every State and county a feudal principality. * * * * *