Sources for Photoplay Music
This music has been out of print since 1928, so it can be hard to find. Keep your eyes open, watch eBay, visit nearby university music libraries, and ask about their special collections. Be very nice to the librarians! A few places have finding aids on line, but -- and it's a big but -- you need to know what you're looking for, and the titles are rarely an indication of the quality or usefulness of the piece. Browsing through the actual music is the most efficient way of searching.
The Photoplay Music Starter Kit
I have assembled a curated collection of over 90 arrangements. They are available from the Photoplay Music Starter Kit page. This will give you a basic toolkit with which to score almost any silent film.
The Silent Film Sound and Music Archive
A growing collection of scanned cue sheets, sheet music, and audio for silent films can be found at the Silent Film Sound and Music Archive. Searching is awkward, but many of the pieces are available as downloadable PDF files, and quite a few are arranged for full orchestra.
University of Colorado, Boulder
The American Music Research Center has finding aids for a variety of their collections, including the Alvin Layton collection, the LaVigne Collection, the Hank Troy collection, and the Grauman Theatre Collection.
University of North Texas Collection
UNT has a very extensive catalog of photoplay music. Search for "Silent Film Music" at the UNT Digital Library for a list of scanned pieces that can be downloaded. Their physical collection goes way beyond these pieces.
University of California Los Angeles (UCLA) Music Library
The Music Library has several collections, not all of which are on line.
The Capitol Theater (New York, NY) Music Collection consists mostly of piano parts. With its 71+ piece orchestra, one would have expected the full orchestrations; and being one of the premiere venues in America for live-orchestra film (directed by Erno Rapée, William Axt, and David Mendoza; all of whom were involved in publishing the Capitol Music Series), it should be an excellent collection. Greg Breed, a San Diego area theatre organist, tells me that this collection was from the projection room where films were scored, so only piano parts were needed. The collection that was in the library for the full orchestra is now at The New York Performing Arts Library..
The Schnauber collection (originally from the Film Music Society) is stored off-site, and when you place an order they have to send someone out to find things -- so it's smart to place one large order rather than a bunch of small ones. The catalog is particularly detailed, and has authors, titles, and arrangers. If you click on a number, it will show you the orchestration, and often the catalog includes film cues that are pencilled on the first violin part.
The New York Public Library
The New York Public Library has a collection that originally belonged to the Capitol Theater in New York. Musician Greg Breed wrote to me:
I have actually obtained music from this collection and each piece is stamped "Projection Room Copy" on the top with a further musical classification. My guess is that the Capitol Theatre had a separate projection room that was used for scoring films, probably equipped with a projector, a piano and file cabinets of this collection. After the score was compiled in the projection room this would probably be used for an assistant to pull the full orchestra parts from the main library(the collection that now resides in the New York Performing Arts Library) to build the scores.
Southern Illinois University of Edwardsville.
These are very helpful people. The Rader collection leans heavily towards classical music, but photoplay and popular music are scattered throughout. There are several other collections at SIUE that are not on line yet.
University of Pittsburgh
The collection at the U of P includes a lot of orchestrated photoplay music in the Mirskey Collection as well as other music. As far as I can tell, you have to search their entire library for composers or titles you're interested in. Searching for "silent film music" (in quotes) brings up a lot of the titles. Use interlibrary loan to get scans of the pieces you're interested in.
The Dorman Hundling Archive at Drake University
Drake University's Dorman Hundling Archive is a collection from a Newton, Iowa movie theater, quite comprehensive. They currently charge $1 per page, and can scan to PDF.
Cleveland Public Library
There are some small orchestra photoplay pieces at the Cleveland Public Library, which also has a large collection of popular sheet music.