VACUUM PLANT
In mercury arc rectifiers progress is illustrated by the latest pumpless steel-tank alr cooled type, the first British design in which the complete unit is mounted on wheels and is withdrawable from its cubicle.

The applications of high vacua have been considerably extended, and diffusion pumps for commercial use are now made in diameters up to 32 inches, together with associated equipment such as vacuum valves and gauges. Many vacuum evaporation plants have been made: a recent application is the deposition of a metal reflecting surface on a synthetic resin backing, thus producing a plastic-based mirror of the shape required in television apparatus. A new 300-kV x-ray equipment has been designed to provide deep therapy in the treatment of cancer; the x-ray tube is fed by a 1000-c/s resonant transformer, giving a self-contained unit that is easy to handle.

RADAR
Marine navigational radar is an important outcome of wartime developments, embodying the experience gained in the Company's extensive work on radar for the services. Many types of wartime equipment had been found useful as navigational aids in fog, rain and darkness, and some of them were fitted on the larger merchant vessels on war service. While not the ideal form of navigational radar, these sets provided data for a provisional specification issued by the Ministry of War Transport in 1945. Within a few months the Company had demonstrated the first production model, and M-V sets, known as Seascan, were subsequently chosen for installation in the first merchant ships to be fitted with British-made commercial radar.

In the latest Seascan model the relative position of the ship and other objects in range is shown on a 9-inch cathode ray tube, and the set has four ranges up to 1, 3, 9, and 30 miles respectively; on the shortest range it is effective down to 50 yards, and ranges can be measured to within 1 per cent of the range scale in use. The bearing of the object can be read directly with a maximum error of 1 degree.

Seascan radar is intended to be used in conjunction with other navigational equipment in order to lessen the risk of accident in bad visibility. By increasing the master's confidence in his judgment of the ship's position it enables him to steer a more direct course and often to dock safely when vessels without radar have to wait for better weather. It has been fitted to some 130 ships ranging from liners like the Caronia and Willem Ruys to Norwegian whaling factory ships, from small coastal craft to the Queen Mary and Queen Elizabeth.