Organ-Pipes of Unusual Shapes

Abstract

THE work of Principal J. A. Aldis (NATURE, Aug. 30, p. 309) on the Bicylindron is not only of practical importance to the scientific pipe-builder, but also constitutes an important addition to the acoustical theory of the organ-pipe. The Bicylindron as invented by Mr. Aldis is new to organ-practice, but there has existed for several hundred years a form of pipe, the theory of which is similar to that of the Bicylindron, although differing greatly in its solution. I refer to the Rohrflöte or Flûte à Cheminée (a particular case of which is found also in the Flauto d'Amore), the invention of which may probably be claimed by the German organ-builders of the seventeenth century. It was found that a stopped pipe of medium scale could be given a very beautiful smoothness of tone if the stopper were perforated by a narrow cylindrical hole, coaxial with the pipe. In old German organs the four-foot stopped diapason in wood was sometimes treated in this way, thereby replacing the rather nasal stopped diapason quality by one more desirable in a small organ. Later, the perforation was extended to metal pipes, a particular stop known as the Rohrflöte being constructed, which owed its peculiar ringing quality to the extension of the main body of the pipe in a short narrow “chimney,” and to the provision of a semicircular mouth with large ears, which enable the pipe to be tuned exactly.