Even if you weren't completely enraptured by the working of the terrible machine, the look on your brother's face alone would be enough to make you want to sit in that chair. He steps aside sweaty to watch you take your turn.
You lower yourself into the chair. You don't have to wait as long as your brother did. You feel a tingle in the base of your spine and you think it must be warmed up from your brother sitting in it and then everything stops for you. The angle of something changes, just slightly, and every atom and instant of you is wracked with more pain than you ever thought possible, and it's still getting stronger. The pain, oppressive, too thick to breathe in, everybody's pain. It shuts your eyes like nails and you are filled and filled and filled with it and you burst and burst and burst with it.
But through it all, You can hold on to your brother's presence, and after a certain point, if you don't hold onto it as hard as you possibly can, You Are Gone.