The Ringling Brothers and Barnum & Bailey Circus opened at the Garden on Thursday. We took in the spectacle from the cheap seats Saturday. The crowd was healthy; we estimate 80 percent attendance (third show of the day!) Clowns are still not funny; the big laugh one got by falling splashily into a pool of white paint suggests that something more violent, in line with Heath Ledger’s Joker, may be in order. (“Mr. Gravity” nemesis doesn’t cut it.) High-wire and derring-do a little drawn out, but riveting nonetheless because where else do you see that? Human cannonballs are still grand wish-fulfillment. Animal acts delightful or torture depending on your point of view; a tiger hopped across the floor on its hind legs; elephants docile as children in a school pageant posed for the cameras. Music, provided by a real band, lively and Disney-ish (sample lyric: “Now we’ll cut this girl in half/or maybe two-thirds/you do the math”); dancing awful. Children liked counting down with the ringmaster and the expensive souvenirs (stuffed tiger: $24). Children and adults both scooped up the blue wizard hats, to emerge later at jam band concerts. The show is at MSG through April 13.