CHAPTER XX.--THE MAGIC-LANTERN, AND ALL ABOUT IT.
I.--PLEASANT HOURS WITH THE MAGIC-LANTERN.--BY A. A. WOOD, F.C.S.
The magic-lantern is of very respectable antiquity. As early as the seventeenth century a Jesuit, named Kircher, had constructed one. He was not unwilling to excite the fears of the persons who witnessed the effects of his apparatus, and not only did he apply the word _magic_ to his lantern, but when exhibiting it he had the darkened room divided into two compartments, in one of which was the lantern, and in the other the spectators. These gazed on the shadowy forms before them in amazement, and were unable to perceive how they were produced.
Kircher’s lantern consisted of a large wooden box, with a door on one side and an opening in front for the reception of a tube containing a magnifying lens. The light was obtained by means of an oil lamp with a polished brass reflector, the smoke of the lamp being conveyed away by a chimney in the top. The pictures exhibited were painted on long strips of glass, and were passed through a groove in the front tube, and although the effects thus obtained must have been of the most imperfect character, yet from their novelty they produced a most profound impression.
There are reasons to believe that the lantern was in use even earlier than the seventeenth century, and that the mysterious figures which the old astrologers produced in the smoke of their mystic fires were produced in the same way as Kircher’s, the smoke forming the screen. With this brief description of the history of the magic-lantern, we must be content. Our main business is to describe the construction and use of the lantern as manufactured now.
The magic-lantern, as now constructed, consists of a box or chamber of japanned tin-plate, with a lamp for the source of light, a large lens to converge the light, and a smaller lens to magnify the object to be exhibited. The large lens is called the _condenser_, and the smaller lens is designated the _objective_. Between the _condenser_ and the _objective_, immediately in front of the former, an aperture is provided for the reception of the painted slide. This aperture is called the slide-holder. We may separate magic-lanterns into three great divisions, the distinguishing difference between them being the kind of light employed. In the first division the lamps are constructed to burn colza or sperm oil; in the second division a mineral oil (purified paraffin) takes the place of the sperm or colza oil; and in the third division some form of lime-light is employed. We will describe these varieties in order.