PLOWS. Since the year 1880 the improvements made in the plow of the ordinary type have concerned mainly the materials and manufacturing methods. Modifications of form have been limited to iiiinor details, important as increasing efficiency and durability, without novelty in the general form. Cast-steel and chilled iron have been liberally adopted for the wearing parts of plow bottoms, and the advan tageous skilful manipulation of these materials is naturally confined to large and costly establish ments, in which alone can the forming and polish ing, of the mould-board be done with due preservation of the evenness of the temper and conservation of the greatest percentage of good wearing surface. The hydraulic process of " chilling " is the most pronounced improvement in the manufacturo of plowshares during the last decade. It cheaply secures uniformity and exactness of contour and extreme hardness of surface. Fig. 1 shows a result of one of the applications of the process. In this instance the under skin of the metal, shown white. is chilled to extreme hardness, and the upper por tion of the material left comparatively soft ; so that, in plowing, the upper face of the share wears away next the edge enough faster than the under face to yield a continuously sharpened edge of the thin chilled skin, avoiding the heavy draft of a dull sham without the need of the usual frequent visits to the smith to have it sharpened. Mr. James Oliver, who has been prominent in the introduction and manufacture of chilled-iron plow bottoms, states t hat his first success was in using hot water in the chills, drying the moisture in the foundry flasks and preventing blow-holes. His next success was in ventilating the chills by introducing grooves along the face of the mould, which allowed the escape of the gases which form within the flask when melted iron is poured in, letting the liquid metal come in direct contact with the face of the chill and all its surface, thus removing all the soft spots in the mould-boards, and leaving the surface smooth and perfect ; but that his crowning success was in the use of the anneal ing process, which deprived the metal of its brittleness. Malleable iron is now used for the frog of the plow. It unites the advantages of economical manufacture and interchange ability," owing to the uniformity easily attained in malleable iron pieces, every frog fitting all plows of the same pattern in case of necessary repairs. Welded frogs or those forged from wrought-iron are liable to spring in manufacture or in use; and if it becomes necessary to supply a plow with a new land-side or mould-board an expert smith is required to fit the new parts. With the malleable iron frog an unskilled person can place the new parts with
ordinary home tools. Composite metal is used with singular success for the share and breast of plows, made by superposing molten crucible steel in a layer on a red-hot malleable founda tion. The ingots thus produced are used in the manufacture of shares, the inner layer of soft iron permitting the tempering of the share hard without crackling or distortion. Some of the best plows are now made from rolled plates of cast-steel highly and evenly tempered and exquisitely polished. Fine, moist earth adheres more annoyingly to a soft, low-tempered than to a hard-tempered surface passing through it. The mould-board particularly should, therefore, be not only well shaped but well tempered to "scour" and prove durable. The large permanent plow manufacturing establishments now keep stocks of duplicate parts for modern-made plows, readily obtained and applied even years after the plow was made. Im provement in outline also marks the products of all the great factories, as will be evident by inspection of the modern hand plow (Fig. 2).
Deere's _RI:dilly Plow (Fig. 3) is a light, three-wheeled implement made of wrought and malleable iron and steel. The wheels are steel and carry the heel of the land-side clear of the furrow bottom, so that there is no weight except on the wheels. The swing of the tongue to right or left unlocks the spindle of the rear furrow wheel, which then becomes a caster, admitting of a square turn of the plow at corners. When the horses are again straightened out this wheel returns directly aft and locks itself rigidly in line with the furrow until again unlocked by the swing of the tongue at the next corner. The plow bottom draws by a steel beam pivoted to the front of the frame, and is thus self-lining. The bottom on this class of plows can be changed to suit different sorts of plowing. In opening a furrow the front furrow wheel is lifted and held up by a suitable lever. The depth of plowing is regulated by the left-hand lever. The amount of land taken is regulated by adjustment of the tongue slightly toward right or left by appropriate means. On arriving at a corner the end of the furrow can still he kept down to standard depth by raising the front furrow wheel slightly at the moment of turning.