Post Office Stamps. We would call the attention of merchants and indeed all who pay postage, to the advertisement of the postmaster, who offers to sell stamps of the value of five cents each for the prepayment of letters. This is the cost of the postage under 300 miles. The stamps should be generally adopted as they will give additional facilities to business men, and save them time in making change. The postmaster will receive nothing for this trouble and his stamps beyond the profit of lost stamps. The disposition of the postmaster to make the new system popular merits the thanks of our citizens. In another column of the same paper appears the advertisement of the postmaster referred to in the editorial. POST OFFICE, _New York, July 14th. 1845_. The public is respectfully informed that the undersigned has caused to be prepared stamps for the prepayment of postage, made for five cents each, which will be sold in parcels of five and upwards. To prevent counterfeits they will be sold only at this office and the branch office. The public may therefore be assured that any stamps which may be offered for sale at any place other than the two post offices are spurious and will not be considered as prepayment. (Signed.) Robert H. Morris, P. M. [Evening papers please copy.] Unfortunately these articles contain no description of the stamp issued, and it will occur to those familiar with the process of engraving stamps at that date, that the production of a stamp as elaborate as the stamp known, in so short a time as elapsed between the date of the first and last of these articles, was either a remarkable piece of work, or had been commenced some time before. Possibly the stamps first issued were not those known to collectors and have never been discovered. Be this as it may, the plate contained more than a single stamp. From double copies that have passed through our hands, we have proof that it consisted of at least eight different varieties, arranged in two horizontal rows of four stamps each, differing in minute details and at different distances apart. There may have been more, but this remains to be verified. The stamp which appears to have occupied the upper left hand corner of the sheet shows in each letter the outlines of the same letters, engraved in black and a little lower down than the white ones, as if the intention had originally been to have the value appear in black on a white label. It is said that the plate is now in the possession of the consolidated Bank Note Companies (American) of New York. At any rate PROOFS were struck from it long after the stamp was out of use, in various colors. NEW YORK POST OFFICE. ISSUE OF JULY 14, 1845.