On my web site is a complete page of patent info and summary for the
Electra / Standard Music Roll company.  This was the work of G Howlett
Davis.  If you read through the actual patents in chronological order
you can see the way that they set out to make workable electrically
operated perforators.  The later patents show the revisions they made
to their earlier work and give you an understanding as to why those
revisions latterly became necessary.  There are plenty of diagrams to
trawl through in the full online patents.  The Howlett Davis perforator
technology is upon the accepted principles of functional and practical
commercial perforation equipment.  See the page at:

  http://www.themodist.com/electra.html

For the full copies go to the US Patent Office web site and simply type
in the numbers ; it's as easy as that.  Although they are quite a long
read, if you do read through them you will get a very good understanding
of the original perforation technology.  Howlett-Davis' first patent
shown (659053) is for a fully developed electrically operated machine
working from a master-roll which could also produce hand-played
recordings.  This patent was filed in 1896 - the year the push-up
pianola was introduced.  It gives you some idea of just how advanced
Howlett-Davis' ideas were at that time.

Sincerely,
Adam Ramet
http://www.themodist.com/