Which one of these figures has bowlegs and which knock-knees? Easy to see that the knees of the one on the right incline toward each other, while the other gentleman carries his legs on a gentle outward curve?
Easy, is it?
Well, it so happens that neither of them is knock-kneed or bow-legged. In fact the legs of both of them are perfectly straight. Take a ruler and prove it. It's just simply a case of the eyes being deceived. An optical illusion and a very common one.
There are a lot of things like that. No two persons see the same thing alike and when a thing is made with intent to deceive, as this was, it would take an expert to discover the deception.
Actors take advantage of this fact in their make-up on the stage, and dressmakers are known to use it. For instance, a short, stout woman wearing a dress with horizontal stripes will look still shorter and fatter with horizontal stripes will look still shorter and fatter and a tall, thin woman wearing a dress with perpendicular stripes will look taller and thinner.