…into the remainder of the fluid. I would like to give a demonstration of the diffusion of vorticity, which requires that Mr. Harvey assist me by smoking his pipe. We're going to do the following. From this, there comes a vortex ring as before. And…

…And it is no smoke in the box. And so it has carrying clean air. Now, as it goes through a mess of smoke, which Harvey will create here, The vorticity is spreading into the other air and picks up some of the smoke. And so the vortex ring, which…

…plan the lecture earlier. There's one of those. What kind of substance is it? It's a screw. What was he showing on this one, Harvey? Harvey tried to make it. Maybe you could talk to him. He liked to try it. We almost made it, but we didn't have…

…plan the lecture earlier. There's one of those. What kind of substance is it? It's a screw. What was he showing on this one, Harvey? Harvey tried to make it. Maybe you could talk to him. He liked to try it. We almost made it, but we didn't have time…