Above.  10 volt 25 watt signal bulbs - the most common.  This bulb voltage allows for line voltage drops when using a 12 volt power supply.  With their 2.5 amp current draw, battery power is not recommended.  Some signal bulbs contain two filaments - a low resistance high power primary filament for normal operation and a high resistance low power filament for fail-over purposes.  During normal operation, the primary filament draws most of the current due to its lower resistance.  When this filament fails, the low power filament provides enough light for signal operation to enable continued movement of the trains.  The low signal intensity also signals the engineer to put a call in for bulb replacement.

Above.  Single aspect H-2 units.  These units do not have the ability to change aspects.  They contain no mechanism for changing aspects and do not have relays or glass bottom covers.

Red roundels with an elongated aluminum holders.  On a normal roundel, the aluminum is just a thin rim around one the edge of the glass cone.  I understand that these were used during WWII to further narrow the beam cast by searchlight signals so as to better avoid the possibility of rail line attack from enemy aircraft.

Above.  Small background for use on ground signals.  Because of the sight hole located above the signal lens, this back ground could also be used on a mast mounted signal.

Above and below.  Maintenance manual for the H and H-2 style searchlight signals.  These were often placed inside the signal for easy reference.  This may account for the condition.

Above.  Side and front view of H-2 outer doublet.  Solid glass.  8 3/8 inches in diameter and two inches thick.

Above.  Signal person’s “Best Buddy”.  This connecting device contains spring clips which slip over the connecting studs on the back of the internal unit.  Wires can then be connected to the screw terminals on the front of the device.  While I believe this unit was primarily designed for bench testing internal units, it could also be used in actual signals where quick change-out of the internal unit may be needed. 

Above and to the left.  Single aspect color light signal.  Appears like a searchlight signal with characteristic ribbed background.  Note the unique adjustment mechanism..