298 REPORTS ON THE STATE OF SCIENCE, ETC. 



less costly silent film would probably by now have become a recognised 

 class-room aid, and films of the kind we still desiderate would be available in 

 both quantity and variety. In the Committee's opinion, the silent film will 

 in the long run replace the optical lantern in the class-room. It is easier to 

 make and to manipulate, and therefore cheaper, than the sound film, and it 

 lends itself readily to the give-and-take between teacher and pupil, which 

 is so characteristic of English teaching method. But the sound film has con- 

 quered in the Picture House and holds the interest of both teachers and 

 children. The Industry, too, has concentrated upon sound films, and the 

 silent film is not made to-day, save for special purposes. The sound film 

 will undoubtedly have its place in the educational scheme ; and, as things 

 are, will probably dominate the situation for a time. 



As though the struggle between sound and silent films were not enough, 

 the sound film itself is a battle-ground of opposing types, both of which are 

 used in the cinemas and neither of which as yet shows signs of being able to 

 oust its rival. In the sound-on-disc type a silent projector exhibits the 

 pictures and a gramophone geared up to it reproduces the sound in syn- 

 chronisation. In the sound-on-film type there is one instrument, the 

 projector, and the sound is reproduced from a track which runs along the 

 side of the film. With both types, of course, amplifiers and loud-speakers 

 are necessary. Both types of instrument have been made available in the 

 sub-standard i6-mm. size during the last few months. It is, of course, a 

 comparatively simple matter to gear up a silent projector with a gramophone 

 so that they will run in synchronisation, but much more than that is needed 

 to secure a realistic correspondence between sight and sound, and a good 

 instrument is bound to be costly. 



The sound-on-film system has its own difficulties to overcome in the 

 recording of an adequate sound track on i6-mm. film. The minimum 

 number of sound variations or cycles which must be recorded in one 

 second, if the reproduction is to be smooth, is 3,000. Frequencies up to 

 10,000 per second are used now in professional cinema work, and higher 

 frequencies still are being experimented with. The rate at which the 

 pictures go through the gate in a sound film is usually 24 per second, as 

 against a minimum of 16 per second with a silent film, and as there are 

 some 40 pictures to the foot of sub-standard i6-mm. film, the corresponding 

 sound variations per second have to be recorded in a length of not more than 

 7 in. The width of the sound track on the narrow i6-mm. film presents 

 another problem. The Committee are aware of only two firms which are 

 prepared to market sub-standard sound-on-film projectors. Other firms 

 are, however, understood to be working at the problem. 



The time has clearly not yet arrived for a considered evaluation of the 

 comparative merits of the two types — at any rate in the sub-standard size. 

 The two systems will be in competition, which from the point of view of the 

 development of cinematography is all to the good, but for the time the pro- 

 duction of sub-standard educational sound films of either type will be inevit- 

 ably impeded. Whether both types will be so developed as to continue to 

 exist alongside, or whether one will become predominant, is a question for 

 the future. 



Suggested National Film Institute. 



The Committee were called into being as an auxiliary for research purposes 

 to the Educational and Cultural Films Commission and similar bodies. They 

 now ask to be continued so that they may be in a position to deal with any of 

 the problems indicated in this Report which may assume special importance, 

 or to co-operate with the Film Commission, should such co-operation be 

 called for. The Committee are glad to know that the Commission is to 



