The Museum Film and Video Archive



From the earliest days of the cinema various inventors have produced different film gauges and systems, sometimes to circumvent patents, sometimes to try and make improvements in picture quality and/or sound reproduction. According to Rogge, Ref. 1, a hundred years of cinema has yielded almost one hundred film formats. An interesting and informative account of many of these is given in Ref 2. Most of these have long since been consigned to oblivion.

The origins of narrow gauge (I hate the description sub-standard) non-theatrical and amateur films go back to 1912, the year when 28mm was the first gauge to use the new non-inflammable tri-acetate film base invented simultaneously in France and the USA. Ten years later in 1922 9.5mm was launched by Pathe Freres to be followed six months later in 1923 by 16mm developed by Eastman-Kodak in the USA.

Commercial/theatrical 35 mn sound-on-film became firmly established in the period 1927-30 whilst development commenced in 1927 to achieve acceptable sound-on-film on 16 mm. The first projector for 16mm S.O.F. was Model PG.30 manufactured in 1930 by the Radio Corporation of America, Ref.2.

A proposed standard for 16mm S.O.F.(1932) was published in the Journal of The Society of Motion Picture Engineers (SMPE) in November 1932 and is reproduced on page 113 of Ref.2. This was adopted by the American Standards Association in 1935. This progressively became accepted as an international standard enabling 16mm "talkie" films to be distributed and shown in virtually every major country. Initially Germany adopted a similar standard but with the optical sound track and perforations on opposite sides of the film to the American standard. These films, to DIN standards, could be projected on machines built to SMPE specifications by revering the films laterally in the gate and then placing a reversing prism in front of projector lens to reverse the image to show correctly on the screen. (The 17.5mm and 9.5mm S.O.F. systems developed primarily for home use during the mid to late 1930s are considered to lie outside of the context of this article).

Once 16mm S.O.F. had been demonstrated to be a practical proposition it quickly became used by traveling showmen, schools, industry and science as well as home entertainment for the small number of the more affluent members of society. It was also used extensively during World War Two by the various armed services to all combatant powers for training and entertainment of the troops.

However, during the early days of 16mm S.O.F in the 1930s, although acceptable for many purposes, the sound quality left much to be desired. Film manufacturers were struggling with emulsion problems because of the considerably different characteristics required for optimum picture quality and optically reduced, or re-recorded 35mm sound tracks. Printer and recording optics were not coated to reduce flare and amplifiers were basically crude with large thermionic valves. The concept of negative feedback was still a novelty and not always fully understood or used. The struggle to improve sound quality on 16mm led to many different recording systems from unilateral variable area to bilateral variable area to variable density to name only three.

Enter Martin Harper, an employee of the Miles Aircraft Company of Woodley, Reading, Berkshire. The reasoned that the quality of 16mm S.O.F. would be considerably improved if 35mm sound tracks could be directly contact printed, full size, on to 16mm picture prints, and then run, during projection at the correct linear speed for 35mm sound tracks of 18" per second. This is more than twice the speed of 16mm S.O.F. of 7.2" per second and left the problem of how to marry the 16mm picture speed of 72" per second with the 35mm sound track speed of 18" per second on the one strip of 16min film.

Harper's solution to this problem was to design a special dual purpose film printer for which he obtained a British Patent Specification No. 509009 for which he applied on January 4th 1938. The complete specification was left on May 14th 1938 and accepted on July 4th 1939. Ref.3.

To achieve his aim the area available on 16mm had to be reallocated. Edge perforations were no longer used. 3mm each side of the film were reserved for sound tracks leaving 10mm in the centre for the width of the 16mm picture frame. The height of a 35mm picture frame is 18.75mm and this was divided as follows:- 2.75mm was utlised used by two perforations of 35mm standard size set either side just inside the 3mm margin reserved for the sound tracks. Then two 8mm spaces for the 16mm frame heights plus the 2.75mm perforations equal the 18.75mm of a 35mm frame. This resulted in the format shown in Fig 1. At later stage of development this format was modified slightly to accommodate a third centrally placed sprocket hole. Fig 2. This was apparently to ease the strain on the film now traveling at the higher speed of 18" per second. (Remember that in the 1930s much tri-acetate film was liable to become brittle and crack and much development was being carried out by the manufacturers to improve its flexibility and long term characteristics). Harper designed a new film perforator Ref.4 to produce this new type of 16mm film stock but this is not mentioned in the Patent Specification.

Martin Harper Martin Harper

In order to obtain his special 16mm projection prints Harper designed a special and rather complicated dual purpose printer. This is described in great detail in the full Patent Specification and is too lengthy and involved to reproduce here. On the first run through the printer the optical sound track of the 35mm film was held in intimate contact with one of the 3mm track width on the 16mm print stock. A second print run was then undertaken whereby the pictures corresponding to the optical track were optically reduced on to the print stock but each successive picture frame was printed on to every other frame on the 16mm film. The process was then repeated for a second reel of 35mm film whereby the other 3mm track on the 16mm film received the second 35mm track and then the pictures of the second 35mm reel were printed into the frames spaces left blank by the first run.

This resulted in a 16mm film which carried two reels of 35mm film and sound with the pictures interlaced and upside down with respect to each other. On projection after running the film through it was not rewound but transferred from the take-up to the feed spool and run through the projector a second time when the second reel of film with its associated sound track would be reproduced.

To achieve this a special Harper projector was designed and made using many of the same components, eg. sprockets and feed rollers as were used in the printer, but no comprehensive details are included in the Patent Specification, only a general mention.

The equipment was designed and made in a research department of Miles Aircraft under the overall direction of Mr. F. G. Miles. The development and constructional aspects were directed throughout by Mr. K. W. Hole. Ref 4.

Ref 4. shows an illustration of a three quarter front view of the Harper 16mm S.O.F projector. Not surprisingly it bears a close resemblance to the larger semi-professional machines of the later 1930s with a rectangular cabinet containing the lamphouse and mechanism with the feed and take up arms and reels on the top. Ref.4 states that the projector would also accommodate normal 16mm S.O.F. prints but no specific details are given as to how this was achieved, except for mention of a small "friction sprocket" driven by the film fitted to the projector about 3" below the gate to allow for the difference in spacing between sound and picture on 35mm films as opposed to the spacing on normal 16mm prints. A switched speed control would also have been necessary but this is not mentioned. A maltese cross and sprocket provided the intermittent motion to minimise wear on the film. A 14 watt amplifier was built into the base of the projector but could be detached as a complete assembly if necessary. It was claimed, Ref. 4, that the undistorted volume produced from the individual loudspeakers was sufficient to fill a hall with about five to six hundred people present! This claim must be regarded as hyperbole; with valve amplifiers of that era working at flill output something like five per cent harmonic distortion would have been about the best achievable with ironcored output transformers and output valves like the ubiquitous 6L6G.

The most powerful lamps of the day for portable 16mm projectors were 1,000 watts with a biplane filament used with conventional condenser optics and uncoated projection lenses. A long throw for an audience in excess of 500 would have needed at least a 3" projection lens of probably f/2.5 aperture. This with the relatively inefficient light source/condenser system and the slow pull down of the maltese cross intermittent would have resulted in a very dim picture. Probably a sensible maximum audience be eighty to one hundred.

There have been a few short and sometimes inaccurate accounts/mentions of the Harper system in magazines since 1948. eg. Refs 5, 6 and 7, and even in The Miles magazine, Ref. 4, this latter states:- "With these alterations the speed of the film through the camera remained the same...."

There was never any intention to produce a camera for the Harper system and none were ever designed or made. The sole function of the printer and projectors was to reproduce existing 35mm films onto the 16mm gauge with enhanced quality of sound reproduction.

Ref 5 states - "alternate frames are upside down each other and alternate frames only are projected". As read, a series of upright and inverted images would be superimposed on each other, alternately, clearly not correct.

It is not known how many Harper projectors were made or what happened to them. The fate of the special film perforator and the dual purpose special printer is also unknown. By the time that the system was completed and demonstrated W.W.2 was about to commence. Improvements in normal 16mm S.O.F. had been rapid and sound reproduction was quite acceptable and in widespread use. The Miles Aircraft Company had to turn its attention to much more urgent wartime production.

It can now he seen that clever as it was the Harper system was the product of misplaced ingenuity and effort. It suffered from a number of short comings including: a) the layout of the film format allowed no provision for edge runners to hold the film flat in the projector gate. Over the long term this would lead to either the sound track or edge of picture frame becoming scratched. Whilst this could be minimised by using a curved gate with edge guides as in the old wartime L.516 there is no claim for this in the literature; this also still leaves the problem of sprocket cheeks.

b) The introduction of a non-standard format when the SMPE specification had become, or was becoming, an internationally accepted standard, and the market was well supplied with a wide variety of 16mm projectors from such established firms as RCA, Bell & Howell, BTH and Gaumont British.

c) Film librarians would have needed special editing and splicing equipment to handle this format and normally libraries instruct borrowers not to rewind films before return to allow them to examine for damage and carry out necessary repairs without the necessity for a double rewind which in itself can cause accumulative damage due to electrostatic attraction of dust and possible cinching.

d) If giving a continuous show the necessity to stop to change a reel from take up to feed arms and rethread the machine would be an unwanted break in the programme. Even if two machines were used it would mean that when printing long films alternate reels would need to be printed on the same 16mm reel; a ready source of confusion?

The Miles Aircraft Company was taken over by Handley Page in the early 1950s which in turn was dissolved in later years. All of the buildings at Reading were dismantled and the original airfield has been developed as an industrial estate and for housing. lt is only remembered in the names of the various local roads, such as Miles Way, Comet Way, Hurricane Way, Spitfire Way, Perimeter Road and many others. In 1993 the Museum of Berkshire Aviation was established on part of the remaining ground previously occupied by the Miles factory near where Douglas Bader crashed in 1931. Although the Museum has several thousands of feet of 16mm film which is currently being examined and catalogued no trace of the Harper system has come to light. As the Film and Video archivist of the Museum I shall be very glad if any reader can add to the present knowledge of the Harper system. It would also be very interesting to know what 35mm films were printed onto the Harper system and what demonstrations, public or private were given. Ref.7 includes a picture of three frames of a 16mm projection print. It will be seen that the films are instantly recognisable by the unusual perforations. Fig.3.

Martin Harper

Acknowledgments are due to the following for supplying information to assist in the compilation of this article:-

Mrs Jean Fostekew. Chairman of the Committee of the Trustees of the Museum of Berkshire Aviation for the loan of Reference 4. Gerald McKee for discussion and a copy of Ref.7. Roderick Bale for Ref 6. Wanton Parfitt for Ref.5.


1. "One Hundred Years of Film Sizes" Michael Rogge. Fotographica Society, Netherlands in 1996 (in Dutch). Reproduced in Raw Deals in English. 2. "Early History of Amateur Motion Picture Film" Glenn E. Matthews & Raife G. Tarkington. Journal of the SMPTE March 1955. Volume 64 pp 105 - 116. 3. Patent Specification No. 509009. January 4th 1938 and July 4th 1939 "Improvements in Apparatus for use with 16mm combined Sound and Picture Film". The Patent has long since expired but copies are available from The British Library for the cost of photocopies to callers but for an all inclusive charge of £10 if ordered by phone. 4. "Sound Reasoning' "Development in Detail" No.9 by Robert Russell. The Miles Magazine, October 1947 pp.32-38. 5. Amateur Cine World "As a Matter of Fact" by Locum. November 1947 pp.442 and 445. 6. Amateur Cine World "As a Matter of Fact" by Locum. February 1948 pp.443 and 445. Amateur Cine World. Letter to Editor from C. E. Cantwell plus illustration of three frames of Harper film. January 1962 pp.44.

Article and photographs by kind permission of the Amateur Cine Enthuiast Magazine.