In the 080601 MMD, Justin Senneff asked about keyframe placement on
fairground organs. He asks:

    "On the German organs the key frame is on the side of the organ and
    not on the back, quite the opposite of Dutch and French organs.
    While this is true, why is it this way?"

Since no one else has answered this, let me make a few humble comments.
The reasons for keyframe placement include tradition, patents, con-
venience, problem resolution, and probably many more.

Regarding tradition, remember that most of the organ builders tended to
be clustered in the same communities; so they knew each other and prob-
ably shared ideas on designs and problem solving.  Also, they tended to
use the same vendors for sub-assemblies and components, which would
push them into using common parts and designs.

Often, an organ manufacturer would use a different design simply to get
around the specifics of someone else's patented design.  Gavioli, in
France, was the originator of the book-operated organ.  So others would
adopt the idea but use a different implementation.

Problem-solving is another reason to change a design.  Keyframes either
inside an organ or hung off the back of the organ were usually driven
by a pulley off the main crankshaft and connected to the keyframe drive
by a leather belt.  I have seen a number of organs that had been well
used where the leather belt began to stretch and slip, producing irreg-
ular tempo or gaps in the music.  Organs with the keyframe on the end
of the organ (typical of German organs) are driven from a set of bevel
gears off the crankshaft, through a rotating shaft running along the
rear of the organ and connected to the keyframe via spur gears or a
small pulley.  These systems are pretty rigid with no slippage possi-
ble.

Organ owners soon found that it was not cost effective to have an oper-
ator stand there and feed individual books through the keyframe.  To
solve this, one method is to fasten a large stack of books together and
put them in a crate with the ends removable.  The books are fed out of
one crate and deposited into a second crate on the other side of the
keyframe.  When the takeup crate was full, the input end of the crate
was re-attached and the crate turned over.  Removing the output end
panel of the crate then allowed this very large book to be fed through
again.  Keyframes on the end of the organ (always away from the
crankshaft) had enough room for these crates.

Another solution to the book feeding problem was to glue a large number
of books together into a continuous loop.  The output of the keyframe
deposited the books into a round-bottomed tub.  The books slid down the
tub and the music was picked up from the other end of the tub and fed
back into the keyframe.  These tubs were generally four or five feet
long.  There wasn't room for one of these tubs underneath a keyframe on
the end of an organ, but a tub would fit nicely under a keyframe on the
back of the organ.

So there are a number of possible reasons for keyframe placement on an
organ.  I am sure our other members can think of lots better ones than
this.

Finally, Justin asks:

    "Also, if Marenghi is French, why [are] their music books on the
    side as well?  What sounds better?"

See above for why Marenghi may have chosen a specific placement for the
keyframe.  Which sounds better?  The sound of an organ is not dependent
on the keyframe, keyless-frame, paper roll frame, or pinned barrel.
The possible exception is that some systems allow for more rapid repe-
tition of notes.  But this is a design execution feature, not a func-
tion of the location of the keyframe.  In general, organs sound good,
bad, or otherwise as a result of their pipe designs, voicing, scale,
and registration.  The keyframe is simply the reader of the stored data
(books or rolls) containing the musical program.

Bob Conant
Bradenton, FL