[Illustration: Figure 174.--Top View of the Hay-Track Roof Extension, showing the ridgeboard and supporting jack-rafters.] [Illustration: Figure 175.--Side view showing plan for building a Hayfork Hood to project from peak of a storage barn. The jack-rafters form a brace to support the end of the hay-track beam.] [Illustration: Figure 176.--Slaughter House. The house should be twelve feet wide. It may be any length to provide storage, but 12 x 12 makes a good beef skinning floor. The windlass shaft should be ten feet above the floor, which requires twelve-foot studding. The wheel is eight feet in diameter and the winding drum is about ten inches. The animal is killed on the incline outside of the building and it lies limp against the revolving door. The door catch is sprung back and the carcass rolls down onto the concrete skinning floor.] Halftone illustration of farm animals or buildings are better used on separate advertising sheets that may be folded in with the letters when wanted. [Illustration: Figure 177.--Rule of Six, Eight and Ten. Diagram showing how to stake the foundation of a farm building so the excavation can be made clear out to the corners without undermining the stakes.] [Illustration: Figure 178.--Roof Truss built strong enough to support the roof of a farm garage without center posts.] [Illustration: Figure 179.--Design of Roof Truss Intended to Span a Farm Garage.] [Illustration: Figure 180.--Roof Pitches. Mow capacity of the different roof pitches is given above the plates in figures.] Typewriters are so common that a hand-written letter is seldom seen among business correspondence. A busy farmer is not likely to acquire much speed with a typewriter, but his son or daughter may. One great advantage is the making of carbon copies. Every letter received is then filed in a letter case in alphabetical order and a carbon copy of each answer is pinned to it for future reference. [Illustration: Figure 181.--Double Corn Crib. Two cribs may be roofed this way as cheaply as to roof the two cribs separately. A storeroom is provided overhead and the bracing prevents the cribs from sagging.] The cost of furnishing a farm office will depend upon the inclinations of the man. A cheap kitchen table may be used instead of an expensive mahogany desk. A new typewriter costs from fifty to ninety dollars, but a rebuilt machine that will do good work may be obtained for twenty. A useful magnifying glass with legs may be bought for a dollar or two. Or considerable money may be invested in a high-powered microscope. SPEED INDICATOR