Further to what Richard Vance wrote about pressure/vacuum systems,
which was very good and should clear up a lot of points for the person
enquiring, I would like to add...

The vacuum operated Aeolian "Grand" (which had a 73-note keyboard,
but was the first to play the standard 58-note roll) was made from 1896
to around 1900.  Yes, some later models of so-called Orchestrelle were
vacuum operated.  I had a model "S" (S = suction) Orchestrelle for ten
years, but in Australia they marketed a model "M" which looked the same
as an "S" and had same stops but was _pressure_ operated.  I have not
seen this in USA or Europe.

The roll motor was not always 6-lobe like player pianos.  The early
46-note models -- Victolian and Princess, from 1889 onwards -- and all
Aeolian Grands which I have seen had a 3-part single acting motor with
pneumatic cloth (vacuum operated).

I have a Model "V" Orchestrelle #1801, dated 1898 which has a pressure
motor in a sealed box which has _four_ large rectangular cylinders
which are leather covered, with card formers to stop it bulging
outwards.  These move up and down vertically like cylinders on a steam
engine and they 'fire' 1-3-2-4.  It is a powerful motor and I have seen
quite a few over here on early pressure Orchestrelle with _wooden_
tracker bars made before 1905.  I have seen 6-lobe motors as Richard
described only on later Orchestrelles with brass tracker bars made
after 1905.

Also, early Orchestrelles were shipped to England ready to play,
assembled with American screws which are of diameters 5, 7, 9, 11, 13,
etc., while later ones as far as I have found were send over here to be
assembled at Hayes factory, west of London with English screws 4, 6, 8,
10, 12, etc.!

The more I research these instruments the more I realise that I know
very little about them, even though I have found over 280 of them world
wide and have played around 100 of them in several countries.

If any one has _original_ Aeolian organ literature I would like to get
a copy from you.  I can offer many instrument and roll catalogs in
exchange which show models not featured in any of the well-known books
on mechanical music.

By the way, is anyone making new 116-note organ rolls yet?  I know
176-note are being made, but there are only four them left here in
England, but around sixty instruments which play 116-note.

I hope this is of interest; it's a pity we can't have an Aeolian Organ
Owners meeting -- there would be many interesting stories to swap!

Kevin McElhone