Seeing the night-time postcards reminded me that I didn't know who did the illumination. Somewhat difficult to find out, since most references lead to Tesla and Westinghouse at the 1893 World's Columbian Exposition.
However, I eventually found the full text of "
The St. Louis electrical handbook; being a guide for visitors from abroad attending the International electrical congress, St. Louis, Mo., September, 1904":
http://www.archive.o...00amer_djvu.txt
Which states
"On the inside of the pillars forming the Colonnade are
vertical lines of lamps, each unit consisting of three
incandescent lights, the first having a clear bulb, the sec-
ond a ruby, and the third an emerald tint. This enables
many color effects to be obtained, as all the lights of one
color can be turned on or any combination of them can
be blended. This is obtained by arranging the colored
lamps upon different circuits.
The current supply is from a three-phase system, sep-
arate feeders extending to each color of light with a com-
mon neutral for all three. Water rheostats are arranged
in each circuit so that the effect of the lights gradually
increasing in brilliancy up to full power can be obtained.
With these different combinations set programs are ar-
ranged for the edification of the evening visitors."
"Three phase" of course must mean it was an alternating current system (a la Westinghouse/Tesla).
The text also says that they expected to use a total of a half million 8-candle power lamps, and arc lighting was not used because it would clash with the glow of low power incandescent lamps.
I also found a less credible source (it has mistakes about the first use of AC lighting) that says the Ferris wheel was powered by electricity in St. Louis. Other soruces say it was powered by a 1000 horsepower reversible steam engine in Chicago (plus it had a second steam engine for backup), and it seems more likely it was also steam powered in St. Louis. This may be sloppy research and refer to the illumination only. One source says it was illuminated by "Edison bulbs"; if so, it must also have had a steam engine with a DC dynamo. Can anyone provide a reference for the electricity source for the Ferris wheel illumination (as opposed to the Expo illumination)?