78 



Prof. J. A. 



Fleming on the 



carbon and with its plane perpendicular to the plane of the 

 horse-shoe. 



The aluminium plate was 5 ceutims. long and 1 centim. 

 wide, and distant from the nearest leg of the carbon about 

 *5 centim. This lamp therefore differed from lamp no. 4 in 

 having the plate outside the carbon loop rather than between 

 the legs. It may be noticed that in this lamp the current 

 here obtained by joining the positive lamp electrode to the 

 plate through a galvanometer was slightly greater when the 

 leg nearest the plate was negative than when it was the positive 

 leg, whereas in the case of lamp No. 2 it is just the reverse. 

 This lamp exhibited also the same effect as lamp No. 4, in 

 that the current flowing between electrode and plate is very 

 liable to "jump" from one value to another even when the 

 lamp is kept at constant volts. The following tabular result 

 of the observations shows this. This lamp is called Lamp 

 No. 6 and was a 50-volt horse-shoe carbon lamp, taking 1*33 

 amperes of current at a working electromotive force of 

 50 volts. 



Table No. 11. Lamp No. 6. Milamperemeier. 



Table showing the potential-difference between the positive 

 electrode of the lamp and the aluminium plate, and the 

 current in milliamperes flowing through a galvanometer 

 connecting them. Vacuum good. 



Working 



volts of the 



lamp. 



Potential- 

 difference of 

 the positive 

 electrode 

 and plate 

 in volts. 



Milliampere 

 current 



through the 

 galvano- 

 meter. 



Working 



volts of the 



lamp. 



Potential - 



difference of 



the positive 



electrode 



and plate 



in volts. 



Milliampere 

 current 



through the 

 galvano- 

 meter. 



32 



•1 



•016 



46 



3-8 



•601 



34 



•3 



•047 



J5 



3-5 



•555 



36 



•6 



•095 



'5 



14-1 



2-23 



37 



•8 



•126 



47 



3-8 



•602 



38 



10 



•158 



., 



16-2 



257 



39 



1-2 



•190 



48 



4-1 



•650 



40 



1-7 



•221 



1 



17-7 



2-80 



41 



2-0 



•317 



49 



42 



-666 



42 



2-3 



•364 



5> 



18-3 



2-90 



43 



2-8 



•444 



50 



19-5 



3-03 



44 



3-1 



•491 



n 



20-0 



3-17 



45 



4-0 



•634 



n 



4-1 



•650 



