The cold brooder house should have a system of heating if birds are to be raised for an early market. The same system of pipes used in the warm brooders should be run around the sides of the building, about 2 or 3 feet from the floor. This will give sufficient heat for the house and keep the birds comfortable. These pipes may be connected with the same heater used for running the warm brooder pipes. In the Northern States, in extremely cold weather, raisers also use the heating pipes in the warm brooder house in addition to the cold brooder pipes. [Illustration: Fig. 18.--Plans of brooder.] An excellent plan is shown in fig. 20 for the arrangement of the heater for connecting the pipes in the warm and cold double brooder house. It will be seen that the heater is placed in the center of the building; the warm brooder house is shown on the right and the cold brooder house with runs attached is shown on the left, and pipes, indicated by dotted lines, run in both directions. This is the most economical house to build and lessens the work in attending the stock. The room in the center of the building will be found very useful and is generally used as the feed room. The heater is in the cellar beneath this room. This plan is used by one of the largest and most successful raisers of ducks on Long Island, and it has his highest indorsement. The building may be of any size, the plan being as successfully carried out on a large scale as on a small one. If a small building is used at first, it may be enlarged on either end to suit the growing business, and extended upward of 100 feet in either direction, thus making the building more than 200 feet in length. The heater must be considered, when put in, with this object in view. A heater capable of heating the 200-foot house can easily be regulated to heat one of 50 feet, but a heater that will heat properly only a 50-foot or 100-foot house would be insufficient to heat the larger one. Another difference between the cold brooder house and the warm brooder house is that the former has outside runs attached. These runs are used for feeding and watering when the weather permits, instead of the feeding troughs inside the house. The ducks should be allowed the freedom of the outside runs as soon as the weather is suitable. Ducks like a life in the outer world, and they will grow more rapidly there than when they are confined to the house. [Illustration: Fig. 19.--Plans of a double brooder house.] [Illustration: Fig. 20.--Plan of a double brooder house, showing arrangement of beating pipes.]