Having worked as a projectionist during my '53-'55 Army stint, I was kept busy enough threading the new "penthouse" Cinemascope four-track sound heads, trimming the carbon arcs, rewinding and boxing the reels, and making changeovers. I can only imagine how the "silent" projectionists dealt with the new technologies of separate disks and reels, keeping them in order, with all the other normal duties plus making good changeovers.
--- On Thu, 6/25/09, George Brock-Nannestad <[log in to unmask]> wrote:
> From: George Brock-Nannestad <[log in to unmask]>
> Subject: Re: [ARSCLIST] Recording Innovations
> To: [log in to unmask]
> Date: Thursday, June 25, 2009, 11:39 AM
> From: Patent Tactics, George
> Hello, Bob Hodge wrote re catching up with missing film
> frames in a sound-on-
> disc projection system so that lip sync could be
> > The method of retard or advance was a special mount
> that allowed the tonearm
> > to be advanced or retarded while the record continued
> at a constant speed.
> > The tonearm mount rotates on a portion of the support
> column below the
> > turntable gearbox.
> > Darned clever those WE engineers!
> ----- yup, you could say that. However, a bit of
> calculation demonstrates
> that there is a limit to the total number of frames for a
> whole reel that
> could be corrected.
> The records ran at 33 1/3 rpm, which calculates to 200
> degrees per second.
> This corresponds to 24 frames. This means that you have to
> move the pivot of
> the tonearm 8.33 degrees for each frame lost, or a right
> angle (give or take)
> for 11 frames lost. If the WE equipment was good and the
> film reasonable I
> suppose this never happened. So, we may conclude that if
> the tonearm mount
> was swivelable over a right angle they would be home free.
> However, the
> differential that was used by other makers was continuously
> variable and did
> not have to be reset when a new reel (corresponding to a
> new disc) was
> Kind regards,