128 



SCIENTIFIC RECREATIONS. 



M. Reynaud cannot be too much commended for so cleverly applying his 

 knowledge of physics in the construction of an apparatus which is at the 

 same time both an optical instrument and a charming source of amusement. 

 Amongst the toys founded upon the .persistency of impressions upon 

 the retina we may instance the " Dazzling Top " (fig. 131). This remarkable 

 invention is quite worthy of a place in every cabinet, and is an ingenious 

 specimen of a perfected Helmholtz top. It is a metallic toy put in motion by 

 means of a cord wound round a groove. The axis is hollow, admits a metallic 

 stem, and fits into a handle which is held in the hand. The top is placed 



Fig. 131. The Dazzling Top. 



upon a little cup in an upright position, and it is then set spinning in thf 

 usual way with the cord. The stem and handle are then withdrawn, and as 

 the top will continue to spin for a long time, discs and various outline shapes 

 can be fixed upon it, and various objects will be shadowed thereon. Cups, 

 bowls, candlesticks, and jugs can be seen plainly revolving as the top carries 

 the wire representation in outline rapidly past the eyes. Coloured cardboard 

 can be worked into various patterns, and much amusement will be created 

 amongst children and young people. 



