The pipes usually seen in the front of an organ belong to the Great organ Open Diapason, long regarded as the foundation tone of the instrument. The Open Diapason may vary in size (or scale) from 9 inches diameter at CC to 3 inches. The average size is about 6 inches. The Diapasons of the celebrated old organ-builders, Father Schmidt, Renatus Harris, Green, Snetzler and others, though small in power, were most musical in tone quality. Though sounding soft near the organ, the tone from these musical stops seems to suffer little loss when traveling to the end of quite a large building. About the year 1862 Schulze, in his celebrated organ at Doncaster, England, brought into prominence a new and much more brilliant and powerful Diapason. The mouths of the pipes were made very wide and they were more freely blown. Schulze's work was imitated by T. C. Lewis, of England, and by Willis. It has also exercised very great influence on the work done by almost all organ-builders in this country, in Germany, and elsewhere. Schulze's method of treatment added largely to the assertiveness and power of the tone, but gave the impression of the pipes being overblown and led to the loss of the beautiful, musical, and singing quality of tone furnished by the older Diapasons. Hard-toned Diapasons became almost the accepted standard. Willis even went so far as to slot all of his Diapason pipes, and Cavaille-Coll sometimes adopted a similar practice. Walker, in England, and Henry Erben, in this country, continued to produce Diapasons having a larger percentage of foundation tone and they and a few other builders thus helped to keep alive the old traditions. In the year 1887 Hope-Jones introduced his discovery that by leathering the lips of the Diapason pipes, narrowing their mouths, inverting their languids and increasing the thickness of the metal, the pipes could be voiced on 10, 20, or even 30-inch wind, without hardness of tone, forcing, or windiness being introduced. He ceased to restrict the toe of the pipe and did all his regulation at the flue. His invention has proved of profound significance to the organ world. The old musical quality, rich in foundation tone, is returning, but with added power. Its use, in place of the hard and empty-toned Diapasons to which we had perforce become accustomed, is rapidly growing. The organs in almost all parts of the world show the Hope-Jones influence. Few builders have failed now to adopt the leathered lip. Wedgwood, in his "Dictionary of Organ Stops," pp. 44, 45, says: