Standards of length and their practical application. A résumé covering the methods employed for the production of standard gauges, to insure uniformity and interchangeability in every department of manufactures, including the reports of Professor Wm. A. Rogers; the committee on standards and gauges, American society of mechanical engineers; the committee of the Master car-builders’ association; and including also the report of the special committee appointed by the Franklin institute, April, 1864