I think this may be the original rule of thumb:

Swift, Jonathan. Travels into Several Remote Nations of the World ... by Lemuel Gulliver. London: Benjamin Motte, 1726, page 108:

The Sempstresses [of Lilliput] took my Measure as I lay on the ground, one standing at my Neck, and another at my Mid-Leg, with a strong Cord extended, that each held by the end, while the third measured the length of the Cord with a Rule of an Inch long. Then they measured my right Thumb, and desired no more; for by a mathematical Computation, that twice round the Thumb is once round the Wrist, and so on to the Neck and the Waist, and by the help of my old Shirt, which I displayed on the Ground before them for a Pattern, they fitted me exactly. [boldface added]