Puzzle: How Was This Sex Chair Used?

[livius drusus]

It's called the siège d'amour, the love chair, and Victoria's son and heir Prince Bertie had it made for his personal use at the famous Parisian brothel of Le Chabanais. It's supposed to have enabled him to have sex with two women at a time without too much effort. (He got a little unwieldy during his long, long wait for the crown.)

The question is, how exactly?





So there are stirrups and handgrips but still if you've got a person on each level, I'm not seeing how the twain meet. It's quite the historical mystery.