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.
A great white shark, for example, would be able to detect a single drop of blood in an Olympic-size pool. Most sharks can detect blood and animal odors from many miles away. Another amazing thing about a shark's sense of smell is that it's directional. The twin nasal cavities act something like your two ears: Smell coming from the left of the shark will arrive at the left cavity just before it arrives at the right cavity. In this way, a shark can figure out where a smell is coming from and head in that direction. Sharks also have a very acute sense of hearing.