THE MAGIC LANTERN. 



drawbridge, is exhibited; the portcullis rises, and a knight in 

 armour issues from it on horseback, and crosses the drawbridge. 



The opening of the portcullis is in this case produced by a 

 moveable plate attached to the slider representing the castle, and 

 the figure of the knight is produced by means of a second lantern, 

 so skilfully managed as to throw the image of the knight upon the 

 screen, and to move it, so as to make it appear to cross the 

 drawbridge. 



11. The optical effect produced by two lanterns working 

 together, called dissolving-views, with which the public has been 

 rendered familiar, at several of the public institutions in London, 

 depends on the alternate opening and closing of the nozzles of two 

 lanterns, in the manner already described, the mistiness and 

 confusion which is exhibited in the gradual disappearance of the 

 one view, and the gradual appearance of the other, arises from 

 the circumstance of the nozzles of both lanterns being partially 

 open at the same moment, so that both views, faintly illuminated, 

 are projected upon the screen at the same time. The mixture of 

 their outline and colours produces the mistiness and confusion, 

 with which all spectators of such exhibitions are familiar. 

 According as the nozzle of the lantern which contains the disap- 

 pearing view, is more and more closed, and that which contains 

 the appearing view more and more open, the latter becomes more 

 and more distinct, and becomes perfectly so, when the one 

 lantern is completely closed, and the other is completely opened. 



12. These, and innumerable other optical effects, are limited in 

 their object to the mere purpose of amusement. Without reject- 

 ing such lighter use of the lantern, its possessors should not, 

 however, forget that it is capable of infinitely more important 

 uses. It may be made extremely useful in impressing upon the 

 minds of young persons the most important events and epochs in 

 history and chronology, by the exhibition of series of portraits 

 and scenes accompanied by observations and comments upon 

 them proceeding from an intelligent instructor. Its use in 

 conveying general notions of natural history is well known. 

 Paintings of the various classes of animals and plants are executed 

 sufficiently well for the purposes of such instruction, and sold by 

 the opticians at a very moderate price. The use of the lantern 

 in this department might be considerably extended, if similar 

 paintings of insects and animalcules, on a magnified scale, could be 

 obtained ; these being still more enlarged by the lantern, many 

 of the effects of the solar microscope might be exhibited, and 

 much instruction imparted. 



13. In the same manner, the first notions of geology might 

 be conveyed by sections of the strata properly painted on the 



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