st.all be nay-able before their delivery at Bay. P'si-Offlce lor transportation. AH mailable matter di'ected to the President, Vice Presi dent and members of Congress, to he prepaid at ihe inaiimgofllce All the departments and heads of departments, except the Post-Ottice l>e,.arime ii, shall prepay all letteis and other tn uter »e..i through the mail. His object is io