[quote="Ed Sukach"]Thinking about this, I remembered an article in the dear, departed ... and severely lamented Camera and Darkroom, expressly about easel tilting and its comparison to view camera tilts, swings, rise, fall ... and other esoteric "jiggling". The title of the article WAS "The Brick Trick".
That was a great publication, and I treasure the ones I have in my bookcase. There was a similar article where someone grafted a four-bladed easel to a ball head and used that to correct distortion. I also seem to remember some company advertising a similar product.
Me I don't use bricks they always leave a mess behind, but use books and any other suitable object I have lying around.