Page 16 - RD_2000-12

interlaced and upside down with respect to each present! This claim must be regarded as
other. On projection, after running the film hyperbole; with valve amplifiers of that era
through it was not rewound but transferred from working at lull output something like five per
the take-up to the feed spool and run through cent harmonic distortion would have been about
the projector a second time when the second the best achievable with ironcored output
reel of film with its associated sound track transformers and output valves like the
would be reproduced. ubiquitous 6L6<J.

To achieve this a special Harper The most powerful lamps of the
projector was designed and made day tor portable 16mm projectors
using many of the same components, were I ,000 watts with a biplane
eg. sprockets and feed rollers as filament used with conventional
were used in the printer, but no condenser optics and uncoated
comprehensive details are included projection lenses. A long throw for
in the Patent Specification, only a an audience in excess of 500
general mention. would have needed at least a 3"
pr~jeetion lens of probably fl2.5
The equipment was designed and aperture. This with the relatively
made in a research department of inetlicient light source/condenser
Miles Aircraft under the overall system and the slow pull down of
direction of Mr. F. G. Miles. The the maltese cross intermittent
development and constructional would have resulted in a very dim
aspects were directed throughout by picture. Probably a sensible
Mr. K W. Hole. Ref4. maximum audience would be
Ref 4. shows an illustration of a eighty to one hundred.
three quarter front view of the There have been a few short and
Harper 16mm S.O.F projector. Not sometimes inaccurate
Fig. 3
surprisingly it bears a close accounts/mentions of the Harper
resemblance to the larger semi- system in magazines since 1948.
professional machines of the later 1930s with a eg. Refs 5, 6 and 7, and even in The Miles
rectangular cabinet containing the lamphouse magazine, Re( 4, this latter states:- "With these
and mechanism with the feed and take up arms alterations the speed of the film through the
and reels on the top. Re£4 states that the camera remained the same .... "
projector would also accommodate normal
16mm S.O.F. prints but no specific details are There was never any intention to produce a
given as to how this was achieved, except for camera for the Harper system and none were
mention of a small "friction sprocket" driven by ever designed or made. The sole function of the
the film fitted to the projector about 3" below printer and projectors was to reproduce existing
the gate to allow for the difference in spacing 35mm films onto the 16mm gauge with
between sound and picture on 35mm films as enhanced quality of sound reproduction.
opposed to the spacing on normal 16mm prints.
A switched speed control would also have been Ref 5 states- "alternate frames are upside down
necessary but this is not mentioned. A maltese 'q «;:~ch o,the~ ~d alt~rnate frames-- only , are
cross and sprocket provided the intermittent projy~~Qdl'. 'As read, a series of upright and
motion to minimise wear on th~ film. A 14 watt inverted images would be superimposed on
amplifier was built into the base of the projector each other, alternately, clearly n9-( <(<)Fr~~t
but could be detached as a complete assembly if
necessary. It was claimed, Re£ 4, that the It is not known how many Harper projectors
undistorted volume produced from the were made or what happened to them. The fate
individual loudspeakers was sufficient to fill a of the special film perforator and the dual
hall with about five to six hundred people purpose special printer is also unknown. By the