The rates of 1863 were slightly modified in 1872, and a local delivery rate of 1 cent was established for newspapers. Two years later a new method of charging postage on newspapers and periodicals posted by publishers or newsagents was introduced. Instead of being charged on each individual packet, postage was to be charged on the gross weight of the newspapers posted by a publisher, irrespective of the number of separate packets to be handled. The rate was 2 cents a pound on newspapers and periodicals published weekly, and 3 cents on those issued less frequently than once a week. These rates only applied to such newspapers and periodicals as were mailed from a known office of publication, or news agency, to regular subscribers or newsagents, and did not apply to those for local delivery. By a statute of 1876 publications designed primarily for advertising purposes, or for circulation free, or at nominal rates, were made third-class matter, and thus excluded from the privilege. In 1879 the present rate of 1 cent a pound (bulk rate) and a revised classification were established. Matter was admitted to the second class on the following conditions:-- _First._--It must regularly be issued at stated intervals as frequently as four times a year, must bear a date of issue, and must be numbered consecutively. _Second._--It must be issued from a known office of publication. _Third._--It must be formed of printed paper sheets, without board, cloth, leather, or other substantial binding, such as distinguish printed books for preservation from periodical publications. _Fourth._--It must be originated and published for the dissemination of information of a public character, or devoted to literature, the sciences, arts, or some special industry, and having a legitimate list of subscribers; _provided_, _however_, that nothing herein contained shall be so construed as to admit to the second-class rate regular publications designed primarily for advertising purposes, or for free circulation, or for circulation at nominal rates. In 1894 the privilege was extended so as to include under certain conditions the periodical publications of benevolent or fraternal societies; and again in 1900, to include the periodical publications issued by State departments of agriculture. It was provided by the statute of 1879 that a supplement may be enclosed with a second-class publication, without subjecting it to extra postage, provided that it is germane to the publication which it supplements, that is to say, is matter supplied in order to complete that to which it is added or supplemented, but omitted from the regular issue for want of space or time, or for greater convenience. It must, however, in every case be issued with the publication.