PHYSICS: R. A. MILLIKAN 
81 
The experiments are made with a device shown in figure 1 by which 
clean new surfaces of potassium, sodium, and lithium can be produced 
by shaving in an extreme vacuum, and photo currents and contact EMF's 
„ ifSxiO LQ {.r 70 Jf to cf <jo <34- ,00 [OS- no ) 
S, /Trft , 
ilfflfflffllMM 
^5 £? Sf a « 6S 
FIG. 6. 
measured immediately thereafter. The tube has a projection toward 
the reader not shown in the diagram with the aid of which the wheel w 
may be rotated by means of an electromagnet similar to F and a third 
armature similar to M and M\ 
