An Interesting Introscope

IT has long been general engineering and scientific practice to employ some form of refracting instrument for the visual inspection of interior details where the detection of small flaws is of the greatest importance. Such instruments vary from the large periscopic torch carried by aircraft inspectors when looking for damage or bad workmanship in the structure of an aeroplane, down to the delicate appliances used by doctors when making similar researches into human beings. The development in recent years of very precisely manufactured details in machinery and armaments, such as the hollow‐stemmed, sodium‐filled valves of aero‐engines, the delicately ground cylinders of hydraulic selector units, the intricate interiors of compression‐ignition injector valves, and the increasingly accurate rifling of the bores of modern small arms has led to the designing of a very neat instrument for the inspection of such parts. This “mechanical eye,” as the manufacturers, the Foster Instrument Co., Ltd., call it, is an Introscope of very varied application. It is almost as delicate in size as the medical profession's appliances, but is more robustly made and easily capable of withstanding the ordinary usage of the inspection room.