Construction of Out-take Flues (Continued)

scientifically designed and are more efficient than wooden cupolas. Not only that, they are lighter and their construction guards against a down draft. It is important that a cupola should extend at least three feet above the ridge of the barn or any surrounding barns if the best results are obtained. The principle is just the same as that of a chimney and if the requirements of an efficient chimney are kept constantly in mind it will aid greatly in constructing these out-take flues. The preceding pages have covered in as brief and concise a manner as possible, the fundamental principles of ventilation. These principles are those on which recognized authorities agree and on which all successful ventilating systems are based. From the explanations given and the illustrations shown, a practical system of ventilation can be figured out to suit any ordinary requirements. There may be special cases, not covered in the suggestions outlined. But THERE IS ALWAYS A WAY TO VENTILATE, and to take care of such cases we shall be glad to have you call upon our BARN PLAN DEPARTMENT for advice and co-operation. This department has made a thorough study of ventilation from a practicalstandpoint and is prepared to assist you in every way possible in figuring out problems of ventilation as well as barn equipment. Size of Out-take Flues Due to the variance in humidity, temperature, height of duct and velocity of wind, it is difficult to outline a cut-and-dried formula for figuring the size of out-take flues which will apply under different climatic conditions, etc. However, most authorities will agree that a safe rule to follow is to allow thirty-two square inches of area for each cow and forty square inches of area for each horse. For example : in a barn stabling ten cows and two horses, the combined area of the out-take flues should equal about four hundred square inches. In other words, a flue twenty inches square, inside measurements, would be ample. Where conditions arise making sharp angles or bends necessary, the area of the flue should be increased to offset the loss of efficiency due to friction. When the flue has to be flattened somewhat, so that its shape is neither round nor square, the area should be relatively greater. This rule is as practical a basis on which to figure as any that has yet been established. Page One Hundred Sixty-seven