Unlike all other instruments, the organ can actually form part of the building in which it performs and its effect on church architecture has been matched only by that of the choir. While the internal workings of the organ have changed little over the centuries, one thing that has changed is the organ case.

Every instrument needs to be put away in a case or bag and the organ is no exception. However, as the organ is fixed, so the case too needs to be a permanent fixture. Organ cases help blend and direct the sound, as well as being a major decorative feature.

Early Organs

The case of the medieval and Renaissance organ looked a bit like an altarpiece. The organ on the west wall of the Cathedral of Notre Dame at Valère sur Sion in Switzerland dates from the mid-fifteenth century and is generally referred to as the oldest playable organ in the world. The doors over its face look like the wings on a medieval altarpiece. As Baroque principles took over in art and architecture, so the grand appearance of the Baroque organ developed.

The organ in the Sint Bavo Kerk, Haarlem, the Netherlands, was built between 1735 and 1738 and was played by the young Mozart. Here, the complex assemblage of pipes is gathered into a series of bundles, making it look like a regal gathering of stooks in a jewelled cornfield, and the whole is topped off by a host of statuary.

Although some organ pipes were made of wood, the most common material was a tin-lead alloy. This was hard and could be polished to a high sheen. Sometimes zinc or copper were used if the tin-lead alloy was judged too expensive. The metal was cast as a sheet, the shape cut out and then beaten round a ‘mandrel’ rather as shoe leather is shaped round a last, and the resulting joint soldered.

Organ Technology

The core of the organ’s ability to make music is its ranks, or rows, of pipes, ranging from very large, for low pitches, to very small, for high pitches. Different pipe shapes and designs produce different tone qualities. Air is either pumped manually or, from the nineteenth century, produced by various mechanical means. It is held under pressure in a reservoir and admitted to the pipes by means of valves or ‘pallets’ operated from a keyboard.

Organs are notable for the variety of sounds they can produce. From the Middle Ages, organs had possessed levers or knobs known as ‘stops’ which, when moved, brought into play a different or additional row of pipes. The player could build up a ‘chorus of principals’ (the fundamental sound of the organ) or choose flute-like or reed-like effects.

Baroque organ builders sought to imitate a wider range of instruments. For example, the organ was capable of a brass effect. The Epistle organ in the Cathedral of Segovia in Spain was built in 1702 and 70 years...

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