Figure 4.
We like to have some idea of what the temperature is inside a kettle grill as foods cook. A grill thermometer inserted through the vents on the lid can tell you if the fire is too hot or if the fire is getting too cool and it's time to add more charcoal. You can control the heat level to some extent by adjusting the vents on the lid and base of the grill. Opening the vents gives the fire more oxygen and will cause the coals to burn hotter at first, but then the fire will cool down more quickly as the coals peter out. Closing the vents partially (don't close the vents all the way or the fire will die) lowers the heat but keeps the coals from burning up too fast and helps the grill retain heat.