British Kinematography (1948)

IS Even in a " dry " construction it is usual — indeed necessary — -to operate the intermittent unit in an oil bath, the level of which must be maintained. The " oil bath " construction enables a constant flow of filtered oil to this vital and heavily loaded unit, also to all gear contacts, as well as to bearings, with exclusion of injurious dirt and grit, and the only attention required is maintenance of oil level. Technically, the case for the oil bath construction does appear overwhelming, but in fairness, I must emphasise that well known projectors of dry types have a deservedly high reputation for good service and reliability. DISCUSSION Mr. Wilkins : You stated that the illumination of the gate is equivalent to 1 h.p. In modern H.I. lamps, the wattage dissipated is equivalent to somewhere near 10 kW. Where is the disparity between the consumption of the lamp and the concentration on the picture gate ? Mr. Robertson : My figure of 1 h.p. was a rough-and-ready computation based upon the screen size and illumination and the dissipation within the lamp. Of the total lamp dissipation only part is picked up and reaches the screen. Mr. R. H. Cricks : Do you think the proposal to build the projector and soundhead as a single unit has sufficient technical advantages to outweigh the obvious commercial defects ? Mr. Robertson : There are obvious technical advantages in combining the two but from the commercial view there are serious drawbacks. Confining one's self to a projector used with a particular sound-head limits the possible market very considerably. Mr. R. H. Cricks : Would not a longitudinally curved gate assist in reducing lateral film buckle and possibly reduce the tension needed on the film ? Mr. Robertson : There are definite technical advantages in some curvature of the gate. The film is stiff in the gate and one can apply side pressure rather than by applying pressure on the surface. But optically, from the point of view of definition, it is more satisfactory that the film should be in a plane than that it should be in a curve. If it is curved, it is preferable that the curve should be with a radius on the same side as the lens, as curvature in that direction facilitates the lens designer in obtaining the utmost quality in his lens. Curvature in the reverse direction makes things more difficult optically, because of the natural aberrations of tlje lens. Mr. R. H. Cricks : One could curve the gate above the aperture, leaving the aperture flat. Mr. Robertson : One has the manufacturing difficulties of combining a radius into a straight plane. Mr. C. G. Heys-Hallett : I must cross swords with Mr. Robertson. Personally, I feel that the days of the separate projector, separate sound-head and separate arc lamp are numbered. TRAINING AND RESEARCH IN SPAIN A few months ago mention was made in this Journal of the very extensive programme of the Institute of Kinematographic Researches and Experiments of Madrid (Instituto de Investigaciones y Experiencias Cinematograficas). Further material from the Director of the Institute, Sefior Victoriano Lopez Garcia, indicates that its curriculum has been further extended both in the scientific and the artistic field. The artistic section is particularly well catered for ; lectures are given in artistic realisation, literary orientation, history of the arts, etc. Amongst other things, the students have to be familiar with Shakespeare and Bernard Shaw. For those interested, the detailed programme of the Madrid Institute can be consulted at the B.K.S. library. J. C. C.