Restoration of a Very Early French Harmonium: The Wind System Part 1

The wind system in a European harmonium is based on the principle of pressure. The wind system supplies a positive movement of air that blows air through the reeds to produce sound. The reed organs produced in the United States, after an initial period of development and experimentation, operated on the principle of negative pressure, or suction. The air is sucked through the reeds.  Each direction of air movement produces a characteristic tone. The European pressure instruments are often louder than their American counterparts, while the American suction organs have a more delicate, devotional tone. Most reed organs made in the U.S. were suction, whereas the demand for suction based reed organs in Europe eventually took a significant part of the market.

The Alexandre harmonium I am restoring is a pressure instrument. In this post I will begin to describe the restoration of the wind system so it functions as it was designed.

 

After I disassembled the wind system and removed it from the case I discovered some significant cracks in the bottom of the chest. The reservoir is attached below this, and this board must be air tight. 

To repair the cracks I widened them with a Japanese saw. These saws are great because they are very sharp and cut with just a few strokes. The reason for widening the cracks was to make the crack uniform in width so that I could splice in a piece of wood.

Once I fitted in the splices I planed down the excess wood so that the surface was flush.

 

After repairing the bottom board I turned my attention to the other boards of the wind system. The bottom of the reservoir was in perfect condition so it required no work other than to replace the relief valve. The boards for the feeder pumps, which are mounted under the reservoir and connect to the pedals, were another story. Here is

a picture of one of the boards, with multiple cracks. These boards were not salvageable so I reproduced them with 3/4" cabinet plywood.

The new feeder pump boards

After finishing the splices in the cracks I glued leather seals over each splice for insurance that the crack wouldn't leak. Sort of a fail safe thing.

Next time--re-covering the ribs for the reservoir and feeder pumps--and the blue paper!

Leather seals on both sides

Leather seals on both sides