HammondWiki - Waterfall Keys

Classic Hammond consoles, such as the B-3, C-3 and A-100, have keys with flat fronts and a slightly radiused edge. These are often referred to as 'waterfall' keys because of their resemblance in profile. The original model A and many other models prior to the '3' series had flat-fronted keys but without a radiused edge. Hammond "originated" this key style by using a piano keyboard as his design prototype and discovering that he could keep production costs lower with this design. The key action is a simple steel spring in the back of the key and a lip on the bottom front of the key that catches the key rail. Thus, the keys all line up neatly without a lot of adjustment.

Of the spinet organs, only the M-series had waterfall keys. Later spinets had to compete with other electronic organ manufacturers and most of them were using DivingBoardKeys. As with the consoles, only the M '3' series has radiused edges.

WaterfallKeys are preferred by non-classical organists because they're easier to play slides (glissandi) on. Unlike a thumb gliss, non-classical organists will often palm smear up and into a chord. This exposes the webbing between the thumb and forefinger to the sharp edges of other types of keys. As a special effect, they are also easier to jamb a matchbook in front to hold down a key while playing elsewhere...