British Kinematography (1951)

158 BRITISH KINEMATOGRAPHY Vol. 18, No. 5 sidering television — and 1 think in spite of the fact that the quality of reproduction is, generally speaking, not good, still the intelligibility of speech or dialogue is probably satisfactory from most home receivers. Because of that fact I think that the questioner may have lost sight of the fact that in a larger auditorium such as the kinema, the intelligibility is to a very considerable degree tied up with fidelity of reproduction, and where, at least in so many instances, the fidelity is poor, intelligibility is also poor. Where that is the case the patron does not get satisfaction. Furthermore, in the kinema there is a large picture, and where there is a picture you are quite aware of the setting; if you have a large orchestra or a chorus, you can see the individuals singing or playing; if you are in a vault, you can plainly see you are in a vault and you expect certain results. I think in such a public place the patrons have preconceived notions as to what the sound normally would be like, and, therefore, if it varies widely from what they have preconceived, they do not get the same satisfaction. I think, therefore, that it is a mistake for anyone to under-estimate \he intelligence or taste of individuals as regards the quality of sound reproduction, and that it is important that the highest possible fidelity be obtained if you wish to cater for the general public. Mr. Kadleigh: I consider that the policy because one thing is bad to make the other thing bad also, is completely untenable. TECHNICAL ABSTRACTS The following abstracts are printed by courtesy of Messrs. Kodak Ltd. CRYSTALLOCHEMICAL MECHANISM OF THE FORMATION AND DEVELOPMENT OF THE LATENT PHOTOGRAPHIC IMAGE P. D. Dankov, /. Phys. Chem. (U.S.S.R.), No. 9, 1949. A theory of latent-image formation and grain development is given which combines most of the features of the Gurney-Mott scheme with proposals previously made by the author. An observation of fundamental importance, which has been neglected by Gurney and Mott, is the excellent correspondence of the atoms in the silver and silver bromide crystals in certain planes. In latent-image formation, the trapping of an electron by the metallic nucleus and the subsequent diffusion of metal ions in the electron field, as suggested by Gurney and Mott, are not necessary. A more probable scheme permits an electron which is approaching the nucleus to combine with an ion, and the neutral atom will add to the nucleus. The shortage of metal ions created near the silver-silver bromide interface will set up a diffusion (not induced by an electrical field) of metal ions towards the nucleus. At the same time, diffusion of " positive holes " will occur away from, the latent-image nucleus towards the grain surface. The existence of electrical fields during the flow of charged particles is of secondary importance. In addition, sensitivity specks are of importance only because of certain cry stallo chemical reasons, and not for the reasons proposed by Gurney and Mott. The crystallochemical idea is elaborated by a detailed description of the positions and motions of atoms in the region of the silver-silver bromide interface formed at (100) planes in the two crystals. According to this scheme, the silver is continually forced away from the interface by migrating silver ions and electrons. The same picture is used in describing the development process, except that electrons are supplied to the nucleus from the developer. A development scheme of Faerman, which proposes that silver is deposited from solution on the free surface of the silver nucleus, is criticized, since it does not explain the observation that the halide grains may be forced away from the silver growth which appears on development. C. R. B. ASHCRAFT COLOR METER /. Biol. Phot. Assoc, No. 1, February, 1950. To use the Ashcraft Color Meter, a dial is set for the desired color temperature. The meter is pointed at the light source, or at a white card (supplied) if used outdoors, and color-correction filters (not supplied) are placed in front of the photocells until a filter is found which causes the meter needle to rest at zero. This filter is then used on the camera. B. M. S.