404 



Prof. Ayrton and Mr. Medley on 



from the published accounts of experiments previously made 

 on glow-lamps, to expect any such result, we thought it 



Fig-. 9. 



might be due to some err*or in our measurements. We 

 therefore made a number of tests to satisfy ourselves that 

 this was not the case. 



A current nearly twice as large as the maximum required 

 to be measured was sent through the manganin strip for 

 several hours, but the deflexion of the d'Arsonval galva- 

 nometer for a given current was not altered, so that the 

 effect was certainly not due to the heating of the strip or 

 galvanometer-coil. 



As the voltmeter was connected with the terminals of the 

 lamp sockets and not with the terminals of the lamps them- 

 selves, we tested whether any resistance was introduced by 

 the sockets, or whether any alteration occurred when they 

 got warm after the lamps had been glowing for some hours. 



