OF ARTS AND SCIENCES. 



131 



be used in the open air, but is impracticable when the waxed plate is 

 covered by a non-conducting material. 



After some further rude work, we constructed the table of which a 

 diagram is given below : — 



Two Bunsen burners are enclosed in an iron case, which is itself 

 enclosed in a wooden case, surrounding it at a distance of 5 to 7 cm. 

 Through the top of the iron case is put a bent copper rod, heated at 

 either elbow by one of the Bunsen flames. The wooden case rests on 

 a floor fastened beneath the table. The ends of the rod, rising from 

 the iron case, and surrounded and held firmly in place by tin cylinders 

 closed at both ends, and themselves secured to enclosing wooden pipes, 

 project some 5 cm. above the top of the table. 



Around this to"p is a guard, within which are wooden cleats, by 

 means of which to level the non-conducting material. This non-con* 



