In the field of communication the principal results have been achieved in the research development of efficient means of fac simile reproduction and television. Facsimiles transmitted by radio waves have already advanced to the stage in which a tabloid journalism of the air is within reach. After years of research, physicists and engineers have abandoned the mechanical scanning devices of early television, and have evolved a method of record ing images upon a mosaic within a vacuum tube. The scene to be televised is focused by an optical system upon this mosaic, made up of globules which are in effect small photo-electric cells. On the mosaic the scene takes the form of a mass of small spots having varying degrees of light intensity. Scanning of the mosaic by means of an electron beam converts the light registered by each globule into an electric impulse. These impulses are amplified and used to modulate the transmitter, which, in turn, transmits the impulses by the medium of radio waves, to the receiver. In order to overcome the physical restrictions of transmitting ultra-short waves beyond the visible horizon, telephone engineers undertook the development of a cable for the linking of distant stations. The outcome has been the production of the so-called coaxial cable, suitable for the establishment of television networks resembling those of radio, as soon as the television industry is in a position to acquire and to finance the laying of this cable in large quantity. Television has now reached the stage in which adequate reception is assured within a limited area about the transmitting station, but progress must be made in the commercial aspects of television be fore this form of intercommunication comes into general use. Research which produced the photo-electric cell is now occupied with finding applications for it, replacing men in routine jobs, speeding manufacture, improving quality, ensuring standardiza tion, and exercising remote control over mechanism. By means of the photo-electric cell electrical action can be brought to bear instantly on what it sees, at any distance, and at any time without the interposition of human hands. The future development of this device carries with it a vast range of future economic effects. Research into the polarization of light offers a solution to the vexed question of glaring headlights on automobiles. Universal adoption of this invaluable safety device must, however, wait upon State legislatures passing laws that impose penalties upon owners of cars who drive with dazzling headlights. Meanwhile, pending the passing of such legislation, other applications for this lam inated glass which polarizes light waves are being exploited. Be tween two sheets of glass is a layer of transparent plastic with mil lions of uniform needle-like crystals in colloidal suspension. All the crystals are oriented in the same direction, so that light waves, instead of vibrating in all planes, are controlled within one.
It has applications in sunglasses, windows and photography. A valuable industrial use has been found for it in the examina tion of strains and stresses of materials. A model of the part to be tested is made of phenolic resinoid plastic. This is subjected to a proportionate stress, and the strain is revealed by the dis tribution pattern of the polarized light transmitted by the model.
Elsewhere in the field of optics research has produced many refine ments in photography. Noteworthy has been the development of the high-speed camera and its employment in the study of strains and stresses in rapidly revolving machines. Optical systems have been further refined and applications ranging from the new 20o-inch telescope to the improvement of lenses for cheap cameras, have been developed. Numerous improvements in film emulsions have increased
the flexibility of photography.
A new form of indoor and outdoor lighting has been introduced as a result of research into the properties of fluorescent materials. Glass tubes, filled with mercury vapour under low pressure, have their inner walls painted with a fluorescent material. On turning on the light-switch an electric spark is introduced into the mercury vapour and ultra-violet radiation is produced. This activates the fluorescent material which glows with high illuminating power. Many coloured lights may thus be obtained which were hitherto unobtainable by incandescence, and a daylight effect can be achieved that is more stable than natural daylight, which varies with the time of day. A conspicuous feature of this fluorescent lighting is the absence of infra-red radiation which, on absorption by glass, results in the generation of heat. This form of lighting, therefore, is well adapted to rooms where temperature must be retained at low levels. Extensive research has been conducted in the production of artificial lightning to facilitate the study of insulating materials suitable for the pro tection of power lines exposed to the hazards of natural lightning.
A century ago the useful metals, excluding the noble metals, were iron, steel, copper, lead, tin, a few of their alloys, and a few other metals more rarely used. As a result of industrial research, today there are more than 5,000 alloys used in industry. The obvious result of the introduction of these has been the construction of new mechanisms not possible to conceive within the narrow limitations of choice offered the engineer of a hundred years ago. The average automobile, for example, has more than 8o different alloys in its construction. Metallurgical research is pressing further toward the production of alloys to meet specifications designed to meet individual needs.
One of the most expensive wastes in metal construction is caused by corrosion, so that it is natural to find much research is devoted to overcoming the disintegration of metal from this cause. Although aluminium has played an important part in protecting susceptible metals from corrosion, and research workers persist in the hope of utilizing magnesium, most of the recent development centres around the applications of stainless irons and steels. The German invention, the so-called "18 and 8" rustless iron, containing 18% chromium and 8% nickel, has had a phenomenal development. For many years stain less steel had been used for cutlery but owing to difficulties in fabri cation the use of stainless iron and steel for structures had been limited, largely because of its tendency to corrode in the neighbour hood of welds. A new welding process has been discovered which does not affect the fabric of the steel or its non-corroding property, so that the past few years have shown great increases in the use of this inexpensive steel.
Much progress has also been made in the electroplating of metals as a protection against corrosion. Silver, gold, and nickel have long been used for plating, but research has facilitated the use of other metals adapted to this process. During the past 55 years chromium plating has come into wide use. Anodic coatings for metals have also been developed. In this process the metal is hung at the anode of an electric circuit in a bath containing either chromic or sulphuric acid. This builds up a coating of the oxide of the metal which acts as a protection.