We have given a description of the simpler forms of the magic-lantern burning sperm or colza oil with a solid wick, and now we will explain the construction of that known as the phantasmagoria lantern. The term ‘phantasmagoria’ was originally applied to a lantern exhibition, in which the figures on the screen varied suddenly in their dimensions, seeming at one time as though they were rushing on to the spectators, and at another vanishing away in the distance. At present this name is used as the distinctive title of a particular form of magic-lantern, otherwise known as the ‘No. 8.’
In the phantasmagoria lantern the condenser consists of two lenses (usually a meniscus convex and a double convex) fitted into a brass cell and placed in the lantern with the concave side towards the lamp. The objective is also formed of two lenses fitted into a brass tube with a diaphragm in front. This tube slides into a brass jacket fixed in front of the lantern, and the lenses are placed in the tube with their convex sides towards the condenser.
Fig. 2.
Fig. 3.
The lamp employed for illuminating the phantasmagoria lantern is the Argand fountain lamp, with hollow cylindrical wick ([Fig. 2]). In preparing this lamp for use, a new cotton should be fitted to it. To do this with facility the cotton should be put on to a taper-stick ([Fig. 3]), on to the base of which the brass wick-holder fits, the cotton can then be pushed on to the wick-holder without any difficulty. The wick-holder and wick are to be replaced in the lamp and screwed down to the bottom, and if there be any superfluous wick standing above the top of the lamp it is to be ignited and allowed to burn itself out. (This must be done before any oil is supplied to the lamp.) The wick being ready, the cistern at the back of the lamp is to be lifted out and inverted, and then filled with oil. The plug or valve which serves to close the orifice in the cistern through which the oil has been poured is to be pulled up and so held while the cistern is replaced in the lamp. The oil should be supplied to the lamp about half an hour before it is required for use, in order that the wick may be thoroughly saturated, and camphorated sperm oil is decidedly the best oil to be used in this lamp. When the lamp is first lighted the wick should be raised but a short distance above the tube that supports it, and after it is ignited all round, the lamp should be replaced in the lantern, the glass chimney (which is screwed on to a metal oxydator and gallery) placed on it, and the wick turned up as high as it will admit of without smoking. The lantern is then to be placed on the stand or table in front of the screen, at a distance of from nine to twelve feet off, a disc of six feet in diameter being obtained at the former distance, and eight feet diameter at the latter. After the lamp has been placed in the sliding tray provided for it at the bottom of the lantern, its position has to be adjusted. If the lamp be too near to the condenser, the centre of the disc will be darkened; if too far off, the margin of the disc will be obscured; the proper distance will be easily ascertained when the lamp is lighted and placed in the lantern.
4.—THE EUPHANERON LANTERN.
The phantasmagoria lantern continued for some years to maintain its character as the best lamp-lit lantern ever made. And this might have still continued, but for the discovery that the art of photography could produce transparent slides suitable for the magic-lantern.