It will be found in the morning that the entire charge of coal is well burned or partly coked. The coked fuel, or that which sticks together in a mass, should be broken up by the poker and more added generally as by rules given in other sections. It must always be remembered that the soft coals mined in different parts of the country have widely varying heat-making capacities. To obtain satisfactory results brands must be selected which have an established reputation for excelling results in small boilers. =For Burning Coke.=--It is best to keep the pot _full_ of fuel--keeping a large body of coke under a low fire rather than a little fuel under a strong fire. It must be remembered that coke makes a very “hot fire” because the coke is free-burning. Care should be taken not to leave drafts on too long in boilers not having regulators. Coke burns best for house-heating purposes with less draft than is required for coal, therefore to keep a low fire the ash-pit draft damper should be kept closed, and the smoke-pipe damper almost entirely closed. The regulator (when used) can be set to keep the dampers about as here advised. Coke is practically smokeless and its quick-burning character makes a cut-off damper in the smoke pipe (which will stay fixed as it may be set) quite necessary. It is well to keep a layer of ashes on the grates and when shaking stop before red-hot coals come through the grate. The coke then burns more slowly, which increases its effectiveness. With some drafts it may be well to “bank the fire” at night with coke--pea coal size. This is a matter of experiment, and depends on the character of the chimney draft. Fire should be tended regularly--two times a day, or four at the outside. With an extra strong draft, at night the fuel should be packed down by tamping with the back of a shovel. With ordinary condition of draft, crushed coke, small egg size, should be used. =Other Rules for Water Boilers=--_To Fill System._--Open the feed-cock when the heater is connected with a city or town water supply; if not, fill by funnel at the expansion tank. Fill until the gage-glass on the expansion tank shows about half full of water. In filling the system see that all air cocks on the radiators are closed. Then beginning with the lower floor, open the air cocks on each radiator, one at a time, until each radiator is filled; then close the air cock and take the next radiators on upper floors until all are filled, after which let the water run until it shows in the gage-glass of the water tank. After the water is heated and in circulation, vent the radiators by opening the air valves as before. Then again allow the water to run into the system until it rises to the proper level in the expansion tank gage-glass. Always keep the apparatus _full of water_ unless the building be vacated during the winter months, when the water should be drawn off to prevent freezing. _Never draw water off with fire in the heater._