Ktesibios of Alexandria, in the 3d cent. B.C., invented the hydraulis, in which water pressure was used to stabilize the wind supply. The pipes were arranged in rows upon the wind chest and the air was permitted to enter any pipe at will by means of wooden sliders. The hydraulis was the prevailing organ for several centuries and reappeared at intervals throughout the Middle Ages.
Evidence of the first purely pneumatic organ is found on an obelisk erected at Byzantium before A.D. 393. Byzantium became the center of organ building in the Middle Ages, and in 757 Constantine V presented a Byzantine organ to Pepin the Short. This is the earliest positive evidence of the appearance of the organ in Western Europe. By the 10th cent., however, organ building had made considerable progress in Germany and England. The organ built c.950 in Winchester Cathedral is said to have had 400 pipes and 26 bellows and required two players and 70 men to operate the bellows.
The keyboard, or manual, was a creation of the 13th cent., making possible the performance of more complex music. The earliest extant music written specifically for organ, dating from the early 14th cent., gives evidence that by then the manuals of the organ had full chromatic scales, at least in the middle registers. Organs in the Middle Ages already had several ranks of pipes, each key causing a number of pipes to sound simultaneously. All were diapasons, or principals, the pipes of timbre characteristic only of the organ, and the various pipes controlled by one key were tuned to the fundamental and several harmonics of a given tone.
The 15th cent. saw considerable development of the organ, particularly in Germany and Flanders. It became possible to sound single pipes from a rank through the use of stops. Mutation and mixture stops that produce several harmonics of the unison pitch came to be used in combination with the unison to vary tone color. Solo stops imitative of other instruments, mainly flute and reed pipes, were added, and the pedal became standard. Until the 19th cent., Italy and England preferred an organ with no pedals.
It was the Flemish and German builders who developed the organ of distinctive and contrasting timbres, and the peak in organ building was reached in the German organ of the baroque, as described by Michael Praetorius in his Syntagma musicum (1618). The greatest organ builder, perhaps of all time, was Gottfried Silbermann (1683-1753) of Dresden. His organs produced a light, transparent tone, ideal for the performance of the great baroque polyphonic music. After this period the art of organ building degenerated, and the organ lost its place in the center of musical life.
The 19th-century desire for a highly expressive organ led to the obscuring of diapason tone by the large number of stops imitative of orchestral tone and to the common employment of the swell and the crescendo pedal. The swell involves enclosing one or more divisions of the organ in a wooden box on one side of which are shutters opened or closed by means of a swell pedal; the crescendo pedal, when gradually opened or closed, adds or takes off stops one by one.
The early 20th cent. saw the electrification of the mechanical parts of the organ, fulfilling the trend toward monstrous size and overwhelming power. In America, this large "king of instruments" became a feature of municipal auditoriums, movie palaces, churches, department stores, schools, and many other institutions. The master architect of these colossal orchestral organs was Ernest M. Skinner. In the early 20th cent., however, Albert Schweitzer was active in the preservation and restoration of many fine old organs, and there was a movement back to the ideals of Silbermann. In the United States, Walter Holtkamp, beginning in 1932, and G. Donald Harrison, in 1935, became the leading figures in this movement. Harrison designed many organs suitable for the performance of music of all periods. In the United States much of the repertoire was performed by the two leading organists of the era, E. Power Biggs and Virgil Fox. By the beginning of the 21st cent., European and American organ builders continued to concentrate on early principles for the construction of their instruments.
The organ repertory is vast and varied. The great organ masterpieces of the 17th and 18th cent. include works by John Bull, Handel, Jan Sweelinck, Girolamo Frescobaldi, and Dietrich Buxtehude. In the compositions of J. S. Bach the capabilities of the organ found their most magnificent expression.
See H. Gleason, Methods of Organ Playing (5th ed. 1962); C. F. Williams, The Story of the Organ (1903, repr. 1972); W. L. Sumner, The Organ (rev ed. 1973); P. Williams and B. Owens, The Organ (1988); C. R. Whitney, All the Stops: The Glorious Pipe Organ and Its American Masters (2003).
Endocrine gland in the brain that produces melatonin. It is large in children and begins to shrink at puberty. The gland may play a significant role in sexual maturation, circadian rhythm and sleep induction, and seasonal affective disorder and depression. In animals it is known to play a major role in sexual development, hibernation, and seasonal breeding.
Learn more about pineal gland with a free trial on Britannica.com.
Partial or complete organ or other body part removed from one site and attached at another. It may come from the same or a different person or an animal. One from the same person—most often a skin graft—is not rejected. Transplants from another person or, especially, an animal are rejected unless they are unusually compatible or have no blood vessels (e.g., the cornea), or if the recipient's immune reaction is suppressed by lifelong drug treatment. Transplanted tissues must match (by blood tests) more closely than blood transfusions. Monoclonal antibodies targeting the cells that cause rejection hold great promise. Tests are now under way with monoclonal antibodies that react with antigens present only on T cells that are participating in rejection, sparing the rest. Rejection matters less in skin grafts, which may need to last only weeks, and bone grafts, whose structure remains after the cells die. In bone-marrow transplants, the donor's marrow cells may attack the recipient's tissues, often fatally. Lung transplants have greater chance of success as part of a heart-and-lung transplant. Seealso heart transplant, kidney transplant.
Learn more about transplant with a free trial on Britannica.com.
Replacement of a diseased or damaged kidney with one from a living relative or a legally dead donor. The former's tissue type is more likely to match, reducing the chance of rejection; but removal puts the donor at risk, and a kidney from a dead donor is more likely to be available. The new kidney is implanted and its blood vessels and ureter sewn in place. A near-normal life may be resumed within two months, but the drugs that prevent rejection leave the patient vulnerable to infection. Seealso transplant.
Learn more about kidney transplant with a free trial on Britannica.com.
Procedure to remove a diseased heart and replace it with a healthy one from a legally dead donor. The first was performed in 1967 by Christiaan Barnard. The diseased heart is removed (except for some atrial tissue to preserve nerve connections to the natural pacemaker). The new heart is put in place and connected to the recipient's blood vessels. Patients and donors are matched for tissue type, but the patient's immune system must still be suppressed to prevent rejection (see immunosuppression). A successful transplant can enable the recipient to have an active life for many years.
Learn more about heart transplant with a free trial on Britannica.com.
The Bruckner Organ, 18th century; in the church of the Abbey of Sankt Florian, Austria
Learn more about organ with a free trial on Britannica.com.
National monument, southwestern Arizona, U.S., at the Mexican border. It was established in 1937. With an area of 330,689 acres (133,929 hectares), it preserves segments of the mountainous Sonoran Desert and is named for the organ-pipe cactus. Wildlife includes Gila monsters, antelope, coyotes, and a variety of birds.
Learn more about Organ Pipe Cactus National Monument with a free trial on Britannica.com.
Learn more about Forster, E(dward) M(organ) with a free trial on Britannica.com.
In Ireland, the word is found in the commonly used phrase "cat melodeon". This simply means that something is awful. For example, if it is raining, one might say that the weather is cat melodeon.