pedal is balanced, the organist does not need to hold it in position, and it will balance at any point in its travel. In addition, this location for most expression pedals, above the center of the pedalboard, is much more convenient for use by both feet if necessary (although it is usually operated with the right foot). Comparison: rachet lever vs. balanced pedals Correspondence to The Musical Times in 1916 debates the merits of both the ratchet lever and balanced pedal systems of expression. One writer suggests that balanced expression pedals are either too sensitive or not sensitive enough and are unable to produce effective sforzandos (though many improvements have been made since this letter was written), and that he knows many organists who are having balanced expression pedals removed. One organist most open to the change suggests that real crescendos and diminuendos are not possible with a ratchet swell lever, as the notches provided are always either just under or just above the required dynamic level. Furthermore, he states that the balanced expression pedal affords the ease of use of either foot, whereas the previous correspondent desired two ratchet levers, one at either side of the pedalboard. Other expression technologies In 1933, Aubrey Thompson-Allen created the "Infinite Speed and Gradation Swell Engine," based on the work of Henry Willis III, the grandson of Father Henry Willis. The mechanism allowed for an infinitesimally slow as well as an instantaneous opening and closing of the swell shades. The spring-loaded expression pedal sits in what would be a half-open position on a normal balanced pedal. The mechanism opens the swell shades at a speed relative to how far the expression pedal is pressed. This uncommon device requires a completely different expressive technique than the balanced expression pedal. It is found on very few organs. Reed organs and harmoniums Reed organs and harmoniums of the late nineteenth and early twentieth centuries featured a pair of bellows pedals at the base of the instrument. When the pedals were pumped up and down, air was drawn across the organ's reeds, producing sound. This capability made the harmonium widely available to homes and small churches, though the dynamic range tended to be limited (not to mention that the organist would eventually tire from pumping). However, these free-reed organs had several ways of controlling their volume and expression. Unlike a pipe organ with a blower, the wind