"Table Turning" is a reference to Séances

On page 366 of Lydia Davis' translation of Swann in Love, the Countess de Monteriender says "...I've never seen anything so powerful...since the table turning!"

What does this mean? Here's one place where I looked in vain for another one of Davis' invaluable footnotes!

Here's the original:

«C’est prodigieux, je n’ai jamais rien vu d’aussi fort…depuis les tables tournantes!»

This picture should explain it all.