I305

Double Reflex's are more powerful than single ones, and the Shadows interposed between the incident Rays and these Reflex's are scarcely sensible. A simple Reflex is that which is formed by one enlighten'd Body alone; whereas a double Reflex receives Light from two, and a triple one, from three. To come then to the proof of our Proposition, let A be a Luminous Body, [Tab. 1. Fig. 6.] A N and A S direct Reflex's, N and S parts illumined by A, O and E parts of the same Bodies, illumined by the Re- flex's, A N E a simple Reflex, and A N O and A S O a double Reflex: the simple Reflex E is formed by the enlighten'd Body B D, and the double Reflex O by the two enlighten'd Bodies B D, and D R; hence the Shadow of the double Reflex will be very thin, and scarce perceptible, being found between the Incident Light and that of the Reflex N O S O.