The usual orders have been given to all our public ships to seize American vessels engaged in the slave trade and bring them in for adjudication, and I have the gratification to state that not one so employed has been discovered, and there is good reason to believe that our flag is now seldom, if at all, disgraced by that traffic.  It is a source of great satisfaction that we are always enabled to recur to the conduct of our Navy with pride and commendation.  As a means of national defense it enjoys the public confidence, and is steadily assuming additional importance.  It is submitted whether a more efficient and equally economical organization of it might not in several respects be effected.  It is supposed that higher grades than now exist by law would be useful.  They would afford well-merited rewards to those who have long and faithfully served their country, present the best incentives to good conduct, and the best means of insuring a proper discipline; destroy the inequality in that respect between military and naval services, and relieve our officers from many inconveniences and mortifications which occur when our vessels meet those of other nations, ours being the only service in which such grades do not exist.

A report of the Postmaster-General, which accompanies this communication, will shew the present state of the Post-Office Department and its general operations for some years past.

There is established by law 88,600 miles of post-roads, on which the mail is now transported 85,700 miles, and contracts have been made for its transportation on all the established routes, with one or two exceptions.  There are 5,240 post-offices in the Union, and as many postmasters.  The gross amount of postage which accrued from the 1st July, 1822, to the 1st July, 1823, was $1,114,345.12.  During the same period the expenditures of the Post-Office Department amounted to $1,169,885.51, and consisted of the following items, viz:  Compensation to postmasters, $353,995.98; incidental expenses, $30,866.37; transportation of the mail, $784,600.08; payments into the Treasury, $423.08.  On the 1st of July last there was due to the Department from postmasters $135,245.28; from late postmasters and contractors, $256,749.31; making a total amount of balances due to the Department of $391,994.59.  These balances embrace all delinquencies of postmasters and contractors which have taken place since the organization of the Department.  There was due by the Department to contractors on the 1st of July last $26,548.64.

The transportation of the mail within five years past has been greatly extended, and the expenditures of the Department proportionably increased.  Although the postage which has accrued within the last three years has fallen short of the expenditures $262,821.46, it appears that collections have been made from the outstanding balances to meet the principal part of the current demands.