THE BOOK OF THE LANTERN. 



201 



Magnetic experiments are always attractive, and can be 

 well shown with the lantern, for they gain greatly by the 

 magnification possible with that instrument. Fig. 52 shows 

 a simple form of slide which can be manufactured without 

 much trouble ; it consists of a bar of soft iron, bent as 

 shown, and pointed at its ends. These ends or poles are 

 brought to within half an inch of each other. Two 

 wooden or cardboard reels, wound with a quantity of silk 

 covered copper wire, complete the arrangement. The 

 battery already recommended can be used with this mag- 

 netic slide. Here are a few experiments possible with the 



FIG. 52. 



contrivance. Drop upon the poles some iron filings, and 

 show that they are not attracted until the battery connec- 

 tion is made, for then and only then has the iron magnetic 

 properties conferred upon it. Drop a number of small 

 French nails, technically known as pins, upon the poles, 

 when they will meet and assume curious forms, until the 

 current is broken, when they will fall upward, as it will 

 appear. A tiny disc of iron attached to the end of a silk 

 thread and hung between the poles will take up a rigid 

 position directly the battery connection is made, a similar 



