During his connection with the firm he had travelled over a large portion of the world on its behalf. His experience at a comparatively early age in organising and carrying out large displays—where the safety of thousands of spectators is in the hands of the directing mind—no doubt did much to develop those qualities of self-reliance and self-confidence which were so marked a characteristic of his Service career. Wing-Commander Brock was responsible for many pyrotechnic inventions, and for the practical development of many ideas and inventions not his own, but which required technical knowledge and experience to ensure success. It is perhaps as the “inventor of the smoke screen” that he is best known, a quite mistaken idea, the fallacy of which a moment’s consideration will show. There are many references to the use of smoke as a screen in classic times and even in mythology. The smoke ball, as we have seen, was a recognised military store up to the middle of the last century. It is just as absurd to credit Commander Brock, or for that matter any living man, with the invention of the use of the smoke screen in warfare as to credit the inventor of a patent fire extinguisher with the idea of putting out fires. What Commander Brock did do was to provide the means when the demand arose of producing smoke suited to the particular purpose for which it was to be used, whether for screens, signalling, or other purposes. As an example the “E” float may be cited. A demand had arisen for a smoke-producing device for use on board merchant ships to assist escape from enemy submarine attack. Commander Brock, with characteristic energy, in a very short space of time produced the “E” float, which for ease in manipulation by untrained operators and volume of smoke produced was probably unsurpassed by any subsequent device, and on the score of cheapness it undoubtedly held the field. This store, which was in reality a triumph of pyrotechnic design, was in appearance so simple as to mislead some at least to whom greater insight might have been credited as to the ingenuity of its design. Counsel at a sitting of the Royal Commission on Awards to Inventors, described the float as “half-a-dozen or so drain rockets in a box.” A remark which might be considered as accurate as to describe a clock as some pieces of metal in a box, were it not for the fact that the box in question contained no drain rockets, or anything resembling them more closely than one firework resembles another designed for quite a different purpose. [Illustration: Smoke Float in Action.]