522 



Mr. E. C Rimington on Luminous 



Fur. 11. 



produced in the bulb. If now a second bulb is placed within 

 the first coil a luminous ring will be formed in it, and the 

 ring in the other bulb will be much weakened or altogether 

 extinguished. Exactly the same effect is produced if a metal 

 plate or closed coil be brought near the first coil in lieu of the 

 bulb. 



Sensitive State of Discharge. 



If a single turn of insulated wire surround one of the 

 exhausted bulbs as in fig. 1, and the spark-gap be adjusted so 

 as to produce a rather faint luminous ring (the fainter the 

 better) ; on approaching the finger and touching the wire at 

 any point the discharge appears to be repelled, and takes the 

 shape shown in fig. 11. Instead of touching the wire with 

 the finger a small piece of tinfoil may 

 be laid between the wire and the bulb, 

 as at A (fig. 11), and this may be touched 

 by the finger or connected to any large 

 object, insulated or otherwise ; the effect 

 produced is the same. Connecting the 

 tinfoil to one of the outer coatings of the 

 jars does not produce this effect, and 

 it is scarcely, if at all, visible when 

 the luminous ring is brilliant, due to 

 a longer spark-gap. With a wire ring 

 of several turns the author has not been 

 able to obtain it. If a turn of bare 

 wire be employed the effect is produced 

 when the finger is brought very near to the wire, but if it be 

 brought into actual contact the effect is no longer visible. 

 This apparently shows that it is due to the capacity between 

 the finger or tinfoil and the wire ; it is probably of 

 same nature as the " sensitive state " in an ordinary vacuum 

 tube, 



Addendum, May 1st, 1893. 



Since writing the above the author has made a further 

 experiment* which at first sight appears to contradict the 

 one f given in the paragraph on u Magnetic Effects of Dis 

 charge/' 



* Called hereafter the second experiment, 

 shown when the paper was read. 



t Called hereafter the first experiment. 



This experiment was 



