So there are a dime a dozen websites which will explain the meaning of stress in typography, so I am just going to give a quick explanation
The first typefaces, designed in the 15th and 16th centuries, emulate calligraphy, therefore there is a certain variation in the stroke of the letters, the transition of the thick to thin in the stroke of the letter is called stress.
When you draw a line through the thinnest points of the letter “O” you can see the angle of the stress.
I thought it would be interesting to actually measure the angle and therefore gauge how “stressed” an old style typeface is.
So I guess it’s safe to say Jenson was a lot more stressed than Garamond, and it was almost a breeze for Caslon!