602 SPANGLED TUBE. 



brought near to the conductor of the machine. The 

 finger-tips of the outstretched hand, the ends of pro- 

 jecting hairs of the head, and many other objects, 

 exhibit luminous points when at a distance of 1 or 2 

 decimetres from the conductor. 



By allowing a discharge to pass through a series of 

 small conducting bodies all separated by a very short 

 distance from each other, sparks can be simultaneously 

 obtained at all the intervals between the successive 

 bodies. This may be well seen in the c spangled tube ' 

 represented in fig. 318, A. . 



A glass tube, about O m '5 long and from 12 to 15 mm 

 wide, is provided with a metal knob at one end and a 



A 



FIG. 318 (A | real size, B real size). 



ring of tinfoil at the other ; between the knob and the 

 ring runs a spiral line of small bits of tinfoil, which are 

 very close to one another. If the end with the ring is 

 taken in the left hand, and the conductor of the machine 

 is repeatedly touched with the knob while the machine 

 is worked continuously with the right hand, a fine spiral 

 series of sparks is obtained each time ; if the wooden 

 ring is upon the conductor, the sparks are more 

 brilliant than without it. If the knob is left for 

 some time in contact with the conductor while the 

 machine is worked, small brushes instead of sparks 

 are often obtained not only between the bits of tinfoil 

 but also extending into the air, and near the conductor 



