1881.] 



the Phenomena of the Electric Disrhnrqe. 



480 



made intormittcnt by an interval of air in one of the connections (an 



air spark). Sec Fig. 20. 



The preparations wliicli were necessary in order tliat this lecture 

 could bo given have occupied a considerable time. In tlic first place, 

 most of the tubes I liave sliown you liad to be specially j) re pared, 

 during the last three montlis, and reserved for this occasion. For all 

 tubes completely alter their character if a current is repeatedly passed 

 through them, and then they no longer present the beautiful phases of 

 stratification you have witnessed. Moreover, it was not possible to 



Fig. 2G. 



remove the battery from ray laboratory, as its construction would not 

 permit it. I therefore have had built up by Messrs. Tisley and Co. 

 an entirely new series, in such a way that the battery can be carried 

 away, when requisite, without injury. The construction of the battery 

 was commenced in June 1879, and was finished in August 1880. 

 The charging of the battery occupied a fortnight, and was finished in 

 the second week in December. 



It only remains for me to thank you for your flattering attendance 

 under such adverse meteorological conditions.* 



♦ Occasioned bj' a very heavy snowstorm on the 18th of January, 



