Figure 8
Power House Generators, Marconi Towers
Three of these five kilovolt direct current generators
produced fifteen kilovolts for the spark transmitter.
The fourth generator was a spare.
The Wayback Machine has a copy of this webpage from the early days:
Power House Generators, Marconi Towers
Archived: 2001 June 9 http://web.archive.org/web/20010609163134/http://www.geocities.com/newscotland1398/marconi100/marpic08.html