180 THE BOOK OF THE LANTERN. 



a great variety of curves. It will be thus seen that this 

 instrument simply gives a variation of the burnt-stick 

 experiment already alluded to. 



Mr. Beale, of Greenwich, has invented a most ingenious 

 and amusing apparatus for the lantern which also depends 

 upon " persistence of vision." This is called the choreuto- 

 scope, and is made in two different forms. In its more elabo- 

 rate shape it consists of a circular plate having upon it figures 

 drawn upon glass, and so arranged with their limbs in 

 different attitudes, zoetrope fashion, that when one figure 

 is rapidly changed for the other, the image seems to be in 

 actual movement. The contrivance is so arranged that 

 before the figure actually changes a little screen obscures 

 it for the moment, so that the movement of the disc is not 

 apparent upon the sheet. Mr. Beale has of late years 

 simplified this instrument. In this case the figures are 

 painted upon a slip of glass about seven inches in length, 

 and by means of a special form of slide they are rapidly 

 brought in front of the lens in the manner just described. 



The most effective set of figures of any is a skeleton, the 

 reason being that it consists only of white on black. 

 Such figures can therefore be cut out, stencil fashion, in 

 a sheet of thin copper-foil ; the openings in this plate per- 

 mitting a far larger amount of light to reach the screen 

 than if the figures were drawn upon glass. 



Another far more perfect and elaborate device for illus- 

 trating the phenomena connected with persistence of 

 vision is an instrument called by the somewhat ponderous 

 title, the Astrometeoroscope. The inventor of this clever 

 piece of apparatus was the Hungarian mechanician, 



