A. A headlight having an electric incandescent lamp in the reflector in
place of the usual oil or acetylene gas flame, and electric instead of
oil cab lamps, the electricity being generated by a small combination
steam-turbine and electric generator. Suitable wiring distributes the
electric current.

45. Q. In what manner does the incandescent headlight differ from the
arc headlight?

A. It is not so powerful. An incandescent or bulb type of lamp takes the
place of the arc lamp in the headlight reflector. The current being less
than is required for an arc, is supplied by a smaller turbine.

46. Q. What type of incandescent lamp is used in the reflector?

A. A low voltage, gas filled bulb, containing a very compact or
concentrated fillament.

47. Q. Why cannot a standard or house type of lamp be successfully used
in the reflector?

A. Because the fillament or light-giving wire inside the bulb is not
sufficiently compact or concentrated to reflect the light in the form of
a beam. The voltage of the house lamp is also too high to be used on a
locomotive installation.

48. Q. How is the lamp held in place in the reflector?

A. By the usual socket, into which the lamp screws. The socket is a part
of the focusing device, one type of which holds the lamp in a horizontal
position, while in the other the lamp is held vertically or upright.

49. Q. Before turning the steam into the turbine, what precautions
should be observed?

A. The turbo-generator should be lubricated by a small amount of black
or engine oil, placed in the cup on the turbine or steam end. On the
generator end, the oil should be maintained within one-half inch of the
top of the hinge-cover cup; using black oil. The drainage of the steam
end is cared for automatically by a three-eighth inch drain pipe without
a valve. The pipe should be kept open.

50. Q. How do you proceed when you wish to use the light?

A. Open the globe valve in the steam pipe to the turbo-generator, at
least two turns. The water-glass, steam and air gauge lamps in the cab,
and the number indicator lamp in the headlight case should light up as
soon as the turbo-generator reaches full speed. A double-throw knife
switch in the cab controls the headlight. In one position the switch
gives the full brilliancy of the headlight. The opposite or "dimmer"
position reduces the brilliancy about one-half. When the switch bar is
in neither position the headlight is entirely out, and only th