1885.] when raised to High Incandescence. 225 



Experiment 5. — No. 9 Lamp (double platinum). 



Filament. 



Shunt. 



Remarks. 



Volts. 



i 



Pi 



a 



Calculated 

 resistance 

 (hot). 



Calculated 

 E.M.F. 



Current in 

 milliamperes. 



Ohms. 



Left. 



Eight. 



Left. 



Right. 



Left. 



Right. 







ohms. 



volts. 



volts. 













80 



0-56 



142-9 



5-46 



5-46 



0-39 



0-39 



140,000 



140,000 





84 



•60 



140-0 



3-8 



3-8 



0-83 



0-83 



45,700 



45,700 





88 



•65 



135 -4 



24-5 



24-5 



1-56 



1-56 



15,700 



15,700 





90 



•68 



132-4 



20 -5 



20-5 



2-05 



2-05 



10,000 



10,000 





94 



•72 



130 -6 



16-2 



16-2 



3 27 



3-27 



4,950 



4,950 





100 



•79 



126-6 



15-4 



15 '4 



5-85 



5-85 



2,630 



2,630 



Slight blue tinge perceptible. 



110 



•92 



119-6 







Doubt 



ful. 









8. Although the maximum effect was produced by Mr. Edison when 

 the plate was fixed between the limbs, he obtained a current when it 

 was fixed in any part of the rarefied space. If the effect was due 

 primarily to the Crookes effect, or to the projection of molecules 

 from the carbon filament on to the metal plate, since this bombard- 

 ment takes place in right lines, we ought to have obtained effects 

 when these lines were projected on the plate, but no effects when they 

 could not strike the plate. Several lamps were made, which are 

 shown in the following sketches. 



9. The metal plate was taken from between the limbs of the fila- 

 ment, and placed at the end of a tube which had a portion of the fila- 

 ment exposed to the plate. 



Fig. 3. 



