56 SCIOPTICON MANUAL. 



mill-wheels, the movable astronomical diagrams, &c. 

 Suppose a mill and the surrounding landscape painted 

 on the fixed disk, and the sails on the disk revolved by 

 rack and pinion, then on turning the handle, the mill 

 appears in operation. 



THE CHROMA/TROPE. 



Fig. 21 represents the pulley form of the chromatrope, 

 bnt can give no idea of the dazzling brilliancy of the 

 effects it produces on the screen. There is nothing it 

 resembles so much as the kaleidoscope, with the addition 

 of constant motion and rapid change. It consists of two 

 disks of glass, painted with an almost endless variety 

 of geometrical and other designs in brilliant colors. By 

 turning the handle shown in the figure, the multiplying 

 band causes the rapid revolution of one disk over the 

 other, producing two apparent motions; and with good 

 designs the result " beggars all description." 



Fig. 91. 



In another form the motion is accomplished by means 

 of a double rack and pinion, instead of a band. As 

 there are two disks, revolving one over the other, each 

 is necessarily furnished with a toothed rack, and the 

 one pinion works both. 



