Move around to the back of the loom and the light is reflected differently off the threads.
As this warp was tied on to the previous one, it's still the same threading: jeans twill, or 3-end twill. The 2/1 twill plays off against the 1/2 twill for some subtle effects with no floats longer than 2.
Just finished reading The Inventor and the Tycoon: The Murderer Eadweard Muybridge, the Entrepreneur Leland Stanford, and the Birth of Moving Pictures. I'd have enjoyed it more if there had been less about the murder and more about moving pictures; however, it was a fascinating account of early movie technology, and I recommend it for photography and movie fans. The sections about 19th century California history were interesting, as well as the bits about the founding of Stanford University. And yes, while galloping, horses at some point have all four hooves off the ground, thus becoming, however briefly, airborne.