So many things I don't know much about

Two examples:

I learned this morning from watching a Youtube video (by someone I don't recall watching before) a succinct history of the development of lighthouses.  It included the point that the very heavy rotating light mechanism worked by floating it in a pool of mercury.  And that the resulting mercury fumes have been speculated as contributing to at least some cases of lighthouse keeper madness.   (A pity that I didn't learn this from The Lighthouse!)

Here is the video.  (The torch he has looks very cool - if slightly dangerous - too.)   

  

 

The second example - from a review of yet another book about Rasputin: 

Beevor’s narrative goes on to show that in fact, the downfall of Emperor Nicholas II and Empress Alexandra was overdetermined. Their reign was a parade of disasters, from the fatal stampede after Nicholas’s coronation that killed more than a thousand people to Nicholas’s decision to continue playing dominoes as the revolution began in February 1917. Beevor quotes one cleareyed contemporary who observed that “the problem was not Rasputin, but the regime that made Rasputin’s influence possible.” 

I've never read much about Russian history, and feel that a lot of people know about the fall of the Romanovs because of the inherent drama and ambiguity of the role of Rasputin.  But I feel I should have heard about the fatal coronation stampede before...