10. In the case of books published in more than one volume, or of periodicals published in numbers, or of engravings, photographs, or other articles published with variations, a copyright is to be entered for each volume or part of a book, or number of a periodical, or variety, as to style, title, or inscription, of any other article. But a book published serially in a periodical, under the same general title, requires only one entry. To _complete_ the copyright on such a work, two copies of each serial part, as well as of the complete work (if published separately), must be deposited. 11. To secure a copyright for a painting, statue, or model or design intended to be perfected as a work of the fine arts, so as to prevent infringement by copying, engraving, or vending such design, a definite description must accompany the application for copyright, and a photograph of the same, at least as large as “cabinet size,” should be mailed to the Librarian of Congress within ten days from the completion of the work or design. 12. Copyrights cannot be granted upon trade-marks, nor upon mere names of companies or articles, nor upon prints or labels intended to be used with any article of manufacture. If protection for such names or labels is desired, application must be made to the Patent Office, where they are registered, at a fee of $6 for labels and $25 for trade-marks. 13. Citizens or residents of the United States only are entitled to copyright. 14. Every applicant for a copyright should state distinctly the full name and residence of the claimant, and whether the right is claimed as author, designer, or proprietor. No affidavit or formal application is required. OFFICE OF THE LIBRARIAN OF CONGRESS, _Washington, 1885_. [Illustration] THE METRIC SYSTEM. The Metric System is a decimal system of measures and weights, based on the meter as its unit, which originated in France during the last decade of the eighteenth century, and has since been adopted by the greater number of States in Europe and America. In the United States its use was authorized in 1866 by Act of Congress. The length of the _meter_ was intended to be one ten-millionth part of the distance from the equator to either pole, measured at the level of the sea, but it is in reality a trifle less. All other units for measuring and weighing are derived from it, and the higher or lower denominations of the same kind of measure are obtained by multiplying or dividing its unit by tens, and prefixing to its name the Greek numerals, _deka_ 10, _hekto_ 100, _kilo_ 1000, or _myria_ 10000, for the higher denominations, and the Latin numerals, _deci_ 1/10, _centi_ 1/100, or _milli_ 1/1000, for the lower. The unit of weight, called the _gram_, is theoretically the weight in vacuo of a cubic centimeter of distilled water at the temperature of maximum density assumed to be 4° C. or 39° 1 Fe.