The foregoing discussion of these annual or otherwise chronologically limited surveys of bibliography is incidental to the main historical purpose of this essay. Such surveys illustrate very effectively an emphasis which has become characteristic of much modern bibliographical work, and especially of bibliographies of bibliographies, since Gabriel Peignot's book of 1812. Being concerned solely with the current production of bibliographies, they have obviously had no occasion to deal historically with bibliographies or to cite bibliographies published before the limits that they set for themselves. This emphasis on currently useful bibliographical tools goes hand in hand with the cooperative aspect of making bibliographies that I shall stress in this chapter. Already in his _Répertoire_ of 1812 Gabriel Peignot had reviewed eighteenth-century bibliography with occasional citations of earlier works that had not been superseded. In 1866 Julius Petzholdt had dealt somewhat more generously than Peignot with Renaissance and seventeenth-century bibliographies, but had scarcely included enough of them to give a picture satisfactory to a historian. Like these predecessors, Joseph Sabin, Léon Vallée, and Henri Stein had shown a marked preference for contemporary works. The uses which bibliographies of bibliographies ordinarily serve explain this preference and make it a reasonable one. The history of mass-production methods in the making of bibliographies has not yet been written. I conjecture that it begins with bibliographies produced more than a century ago by the German publisher Wilhelm Engelmann. His firm continued and revised some bibliographies established by Johann Samuel Ersch (1766-1828), whose scholarly and bibliographical activity began in the eighteenth century. It is not entirely clear whether Ersch himself had already adopted something like mass-production methods. However this may be, the titles and the nature of many bibliographies produced by T. C. F. Enslin (1787-1851) and Wilhelm Engelmann (1808-1878), who made new editions of some of Enslin's bibliographies as well as many of his own, virtually imply such methods. Information about the making of these bibliographies and those of F. A. Wilhelm Müldener (1830-1900), who seems to have worked in the same way, is difficult to obtain.[183] The compilation and publication of bibliographies by printers and publishers rather than scholars has been continued by such American firms as the Library Bureau (now no longer in existence), R. R. Bowker & Co., and H. W. Wilson Co. These firms have actively supported the making of bibliographies in this country for more than two generations.[184]