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Hovery describes its beauty thus: "Each rosette is made of countless fibrous crystals; each tiny crystal is in itself a study; each fascicle of carved prisms is wonderful and the whole glorious blossom is a miracle of beauty.
The first of these, which is plane and simple, is used when it is desired to give the fascicle all the concentration possible; the other, which consists of cylindrical lenses, spreads the fascicle horizontally, so as to make it cover a wider space. The range of the concentrated fascicle is about 86,000 feet.
Various interesting experiments have been made with a view to utilizing luminous captive balloons for optical communications. As we have already seen, this maybe effected by using opaque balloons, and throwing upon them at unequal intervals a luminous fascicle by means of a projector.
It possesses so remarkable optical properties that it has been adopted by nearly all powers. The fascicle of light that it emits has a perfect concentration. In front of the projector there are two doors.
If, then, in the line of travel of the luminous fascicle emitted by the optical apparatus, or in a portion of such fascicle, we interpose a fragment of selenium connected with the two poles of a local pile, it is easy to see that the current from the latter will be opened or closed according as the luminous ray from the apparatus will or will not strike the selenium, and that the length of time during which the current passes will depend upon the length of the luminous attacks.
I shall, therefore, begin this chapter with a number of letters written by the composer during this period to his friend Franchomme, and then endeavour to describe Chopin's mode of life, friends, character, &c. The following fascicle of letters, although containing less about the writer's thoughts, feelings, and doings than we could wish, affords nevertheless matter of interest.
"That explains," he answered. He drew a fresh sheet of paper toward him as he looked at me. I glanced from him about his apartment and back to the little table. A fascicle marked very distinctly "1" caught my attention, and I took it up. I smiled in his friendly eyes. "Very well," said I, suddenly at my ease, and he nodded and went on writing.
When we wish to correspond at a short distance, say two miles, and make signals visible from the entire horizon, the mirror, A, is put in place, so that it shall reflect the luminous fascicle vertically. The fascicle, at a distance of about fifty feet, meets a white balloon which it renders visible from every point in the horizon.
Two French officers, working independently, have hit upon the same idea of receiving the indications transmitted by the vibration of the luminous fascicle directly upon their travel. The method consists in the use of that peculiar property of selenium of becoming a good conductor under the action of a luminous ray, while in darkness it totally prevents the passage of the electric current.
Opposite the two slits, a and a', there are two powerful converging lenses, l and l', whose foci coincide with two sorts of selenium plate rheostat, z and z'. The result of this arrangement is that as soon as one of the slits, as a consequence of the displacement of the helix, r, allows a luminous fascicle to escape, this latter falls upon the corresponding lens, which concentrates it and sends it to the selenium plates just mentioned.
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