vii WORK AT MANCHESTER 169 



was put up outside, it frequently rained and all sorts of 

 difficulties would arise. Sometimes the zincs in some 

 of the cells were not properly amalgamated and they 

 were corroded very rapidly, or, what was worse, some- 

 times the porous cells had been injured in transit and 

 the nitric acid got at the zinc, and then there was a 

 nice mess, and the battery had to be taken to pieces 

 and cleaned. 



The responsibility of making all the experi- 

 ments succeed is no light matter, and no one but 

 those who have gone through the experience can 

 understand the excitement and worry which such 

 lectures entail. The lecturer has to assume a confident 

 air, and yet he cannot be certain that at the last 

 moment he will be able to perform what he has pro- 

 mised. Where merely drawings have to be exhibited 

 or slides shown the thing is entirely different. To 

 carry out a lecture on spectrum analysis at that time 

 without help of the dynamo required all one's presence 

 of mind and skill. Nothing detracts more from the 

 effect of a lecture than when a certain result is antici- 

 pated and explained beforehand, as it is necessary to 

 do, the thing does not come off. It does not mend 

 matters when the lecturer says, " Oh, well, this is not 

 very important ; we will go on to the next." 



I did not, as a rule, allow my public lecturing to 

 interfere with my college work, and I have often, after 

 packing up all my apparatus, a matter of no slight 

 difficulty, travelled late at night in order to meet my 

 class at nine o'clock the next morning. I remember 

 on one occasion I had to give a lecture in Birmingham. 

 I met my class at Owens College in the morning ; I 

 packed all my apparatus after the lecture, took the 

 train to Birmingham, arrived there about three o'clock, 

 worked for three or four hours in preparing the lecture. 



