One of the most serious problems in the design of a machine shed is the insertion of doors. Wide doors are an absolute necessity, especially for certain machines. An eight-foot door is large enough for the majority of farm machines, even allowing the modern binder with its folding grain dividers to enter in safety. The wide drill, the rake, and several other implements require a much wider door than this and it may be necessary to provide an opening 12 or even 14 feet wide. This leaves a long unsupported section of the plate directly above the doorway. To keep it and the roof from sagging, special provision must be made either by putting in an exceptionally strong plate at this point, by building up a small wooden truss, or by making a truss of wood and iron as shown in the illustration. (Fig. 10.) The doors themselves should be very solidly and substantially made. It is a matter of good practice to have as few doors as possible. In the average machine shed one 8-foot door and one 12 or 14-foot door are sufficient to meet requirements. A door wider than four feet should not be swung on hinges under any circumstances, as it is sure to pull out the hinges or to sag very badly. Sliding doors of good construction are to be recommended in preference to hinged doors (Fig. 12). It is entirely possible to make a good close-fitting door of this type and there need never be any trouble in its operation. The use of other buildings for the storage of farm implements is not a desirable procedure except in certain instances, such as keeping wagons in the driveway of cribs, leaving the spreader at the end of an alleyway of a barn for convenience in loading, etc. In general, other buildings are much more expensive than a machine shed and those portions of them devoted to the storage of farm implements could in most cases be more profitably used, especially when the very small unit floor-space cost of a machine shed is taken into consideration. Then, too, if a special place is not provided for the implements, the farm animals may come in contact with them, causing injury of the animals or damage to the machines. REPRESENTATIVE TYPES OF SHEDS