660 
Prof.  Fleming  on  Oscillation  Valves 
loop.  The  oscillation  valve  is  most  conveniently  mounted  for 
tins  purpose  on  a  special  form  of  stand  (see  fig.  1).  In  using 
the  valve  the   carbon  filament    must    be    brought  to  brio-ht 
Fi°\  1. 
B,  Exhausted  glass  bulb.     C,  Nickel  cylinder.    TL  T2.  Carbon  filament 
terminals.     T3,  lusulated  cylinder  terminal. 
incandescence,  about  equal  to  that  which  in  a  carbon  glow-lamp 
would  correspond  to  a  so-called  "efficiency"  of  3  watts  per 
candle.     So  used,  the  valve  euables  us  to  employ  a  sensitive 
Fi*.  2. 
P,  Primary  oscillation  circuit.  S;  Secondary  oscillation  circuit. 
G,  Galvanometer.  V,  Valve.  B7  12-volt  battery  for  incan- 
descing filament  of  valve. 
mirror-galvanometer  of  the  ordinary  type  to  detect  the 
presence  of  electric  oscillations  in  a  circuit  and  to  institute 
comparative  measurements. 
