That an article possesses the corporeal characteristics of a book is of little consequence. The _literary_ substance, not the material form, primarily determines the matter. An article contributed to a newspaper or a periodical--although but a few paragraphs in length--is a "book" under the copyright law, while a bookkeeper's ledger, to all outward appearance answering the description, is not a "book" so far as registering its title to secure copyright is concerned. A calendar whose main features are literary may doubtless be properly registered as a "book," but a pack of playing cards with pictures on the backs, even though each card may be furnished with a linen guard and all bound up, with a plausible title-page, so as to resemble a book, is not a "book" in the meaning of the copyright law. Orderly arranged information produced in a form which would commonly be termed a chart cannot be registered under that designation which in the copyright law is applicable only to a chartographical work, but may properly be called a "book"; while a so-called book of coupons, or railway tickets, or of blank forms, cannot be thus entitled. In brief, it should be a book in the ordinary understanding of a work of _literature_ or art, and may not include a production whose main feature is some original idea, however ingenious or fanciful its form may be, or is of the character of something invented. Invention must look for protection to the patent law. 2. _The nature of the protection secured._