Reset Button. Most boilers have safety devices built in, so if these are tripped a simple reset may get your whole system working. The reset button is normally on the front of the boiler. Sometimes it's a dial that needs resetting to zero and turned back on.
A typical diffusion constant for a medium-sized molecule in water is about . If we want the smell to travel a quarter mile, or a little less than , we get a speed of. This speed is fantastically slow, and says that it would take ten million years for blood to diffuse out to a shark a quarter mile away.
The shark's nose may work so well because it doesn't have to do anything else. Sharks use their noses just for smelling. Breathing is accomplished with a shark's gills, and the shark's sense of smell is not connected to its mouth in any way. Sharks often don't know how something is going to taste until they've taken a bite. This is how some people are able to escape from a shark attack -- the shark gets a little nibble of a foot and decides to reject the prey. Can sharks hear as well as they smell? Find out on the next page.