De Chales wrote that for many things this method of projection--direct with a strong light source--was “the best and most certain.” Doubtless he was right, considering available means. He also pointed out the military uses of the projector and other mirror-lens devices. Today in enemy waters or where hostile sea or aircraft are expected and a “radio silence” must be maintained--ships and planes must use optical signaling devices and de Chales was the first to consider carefully this subject. De Chales’ most important refinement in the projector was the introduction of a two-lens projection system. He described in his book how the magic lantern first came to his attention. “We have seen here at Lyons a dioptric machine, called a magic lantern. Rays of light are projected through a tube for a distance of ten or twelve feet. An enlarged image, about four feet in diameter, is shown in all its colors.” The effect was considered wonderful, according to de Chales. He noted, however, that a convex lens was used but pointed out that it would be better to use a double lens “as he demonstrated.” De Chales did not discard the concave mirror, used as the light collector on almost all types of projectors from Kircher’s to those of the present day. In a subsequent chapter de Chales gave more information on this subject. “As I have indicated in the preceding chapter a learned Dane” (very likely the same Walgenstein of whom Kircher wrote as a popularizer of his lantern projector) “came to Lyons in the year 1655.” De Chales continued, “This Dane was well versed in optics and among other things showed a lantern.” De Chales again noted how he had developed an improvement, using two lenses, which made possible a projection to the then amazing distance of 20 feet. The present projection “throw” at the Radio City Music Hall, Rockefeller Center, New York, is approximately 200 feet. In addition to optics and many other fields of study, de Chales was interested in navigation. He wrote a book, probably on the order of the King’s general staff, _The Art of Navigation demonstrated by principle and proved by many observations drawn from practical experience_. He devised a paddle-wheel ship that would go against the current, “without sails, without oars and without the traction of any animal”--surely a military weapon! His most important military work was _The Art of Fortifying and Defending and Attacking according to the French, Dutch, Italian and Spanish Methods_. De Chales mentioned in his writings Alhazen, Witelo and other ancient authorities. He must have read the first edition of Kircher’s book and also Gaspar Schott’s before his own was written. However, de Chales made a definite improvement with his lens system which is essentially the modern one. Also, his work helped to popularize and extend the art and science of light and shadow. He was another strange man in this complex story--a missionary, a teacher and a military expert.