I Make Myself Invisible in Articles by Aleister Crowley.
“Later, when I was transferring my apparatus to my house in Scotland, I employed two workmen to remove the mirrors. As they were working they were suddenly overcome, knocked out by unseen assailants. It took several hours to revive them.
People passing the doorway suddenly fell down in fits. That flat remained without a tenant for years after I had left it. All this was because I had not enough experience to control the forces.” [via, also]