Do horses legs leave the ground at a gallop?

There’s a famous photo series by Eadweard Muybridge that shows, unequivocally, that while galloping all four of a horse’s legs leave the ground. I’d always heard that’s what they trying to find out at the time, but from what I’ve read it was more a question of at what points do a horse’s legs leave the ground. The photos show the somewhat surprising state of leaving the ground while the horse’s legs are tucked, not when they are outstretched. It’s a lovely example of what Edward Tufte calls small multiples .