I play with tarot cards, so it does not concern me if the roof is a triangle. So... ( the formatting is wonky, sorry)
I imagine Russell was into pyramidology , a lot of upper class folks passed the time speculating about things like that and the spiritualism type religions were very popular among the upper class- which Russell was. many of them wre into séances.
for the paranoid among us I included the link about triangles. Oh and I have a cousin who is a Free Mason now. He says all those rumors are nonsense.
http://en.wikipedia.org/wiki/Pyramidology
http://en.wikipedia.org/wiki/Spiritualist_church
http://www.bibliotecapleyades.net/sociopolitica/codex_magica/codex_magica18.htm