Pieces or packages of third-class matter, when of such size or form as to prevent ready facing and tying in bundles and requiring individual distributing throughout, shall be subject to a minimum charge of 3 cents each. Among the articles to which the 3 cent minimum charge shall apply are those exceeding 9 inches in width or 12 inches in length, or less than 3 inches in width and 4 inches in length; round, cylindrical, or other irregularly shaped pieces or packages, and those with contents forming a hump or which are otherwise so uneven as to prevent stacking or tying in packages; also articles in bags or which are addressed by means of tags. FOURTH CLASS must weigh in excess of 8 ounces; includes books, circulars, and other mat- ter wholly in print, proof sheets, corrected proof sheets, and manuscript copy accompanying same, merchandise (including farm and factory prod- ucts), and all other mailable matter not included in the first, second and third classes. Exceptions. Rate on books, catalogues and library books. Apply at Post Office. Size and Weight Limit. The limit of size shall be 72 inches in length and girth combined and the limit of weight shall be over 8 ounces and not exceeding 40 pounds in the first and second zones and 20 pounds in the third to eighth zones, with certain exceptions; consult local post office. Rate on Parcels for Armed Forces Overseas. The zone rate is applicable from the Post Office where mailed to the Post Office in care of which the parcel is addressed. AIR MAIL (Domestic). Limit 8 ounces. 6 cents per ounce or fraction, including all U. S. possessions, A.P.O.'s, F.P.O.'s, Canada and Mexico.