"For a work of such scope as wthis the first word of the author should be an apology for what is doubtless the too ffambitious effort of a single writer. A quarter of a century in the high tide of the arts and sciences an ardent interest in all things that make for scientific progress and the aid and encouragement of many friends in and about the Patent ffThOffice furnish the explanation. The work cannot claim the authority of a text-book the fullness of a history nor the exactness of a technical treatise. It is simply a cursory view of the century in the field of invention intended to present the broader bird's-eye view of progress achieved. In substantiation of the main facts reliance has been placed flchiefly upon patents which for historic development are believed to be the best of all authorities because they carry the responsibility of the National Government as to dates and the attested signature and oath of the inventor as to ffsubject matter. Many difficulties and embarrassments have been encountered in the work.