Hi guys i was reading through da vincis notebooks on the proportions of the face and found what may be a mishap, or maybe just a mistake in translation
Da vinci says that the face is from the hairline to the chin, and that the face can be separated into thirds by lines at the brow and the base of the nose, which by his illustration he means the base of the nostrils. He says that the distance from the base of the nose(nostrils) to the parting of the lips is 1/7 of the face. Also he says that the distance from the parting of the lips to the chin is 1/4.
Now, if we suppose a face of 200 cm, and split it into thirds, that would make 3 sections of 66.6(repeating) cm. And if we took the bottom fourth of the face it would be 50 cm. With that bottom section of 66.6 cm we take off the bottom 50 cm from the parting of the lips to the chin that leaves 16.6 cm for the distance from the bottom of the nose to the parting of the lips. If one does the math then, 16.6 is not 1/7 of 200, but it is 1/12.
I foresee some people misunderstanding me so heres a bit of a diagram.
I mean, proportions alter slightly between different individuals, races, genders, ages... I measured out thirds, quarters and a seventh in Photoshop and checked them against photos and the mona lisa - they vary in their correctness and the only solid rule seems to be the third between brow and nose - even that isn't exact.
If he got his maths wrong - well technically, yes he did (i'll take your word for it, fractions were never my strong suit). But I don't think he inteded for it to be taken with such pedantry. As rough measurements, they work out pretty well.