PLOW. 124 PLOW. plows,' with short, steep, ovtTli;uij;iiig iiuildboaid, which break up tlic furrow .-.lice a!i<] pulverize the soil. Knglish plows are generally of the first type. The modern American plow is generally of the second type, although |)l()ws of the tirst type are made and used to a considerable extent for special purposes in America. It may be said to date from September 1, 1819, when Jethro FlO. 4. MOUNTED OAXO PLOW. Wood of Scipio, New York, took out a patent for an improved cast-iron plow having the mold- board (of pulverizing type), share, and land- side east in three separate pieces so that they could be replaced by new parts «hen worn. Ander- son found that Hr> per cent, of the draught of the plow is consunieil in cutting the furrow slice, 12 ])er cent, in turning it. and Xi per cent, by the sole and land side. Since such a small per- centage of the energy rcipiired in plowing is con- sumed by the mold-board, it would seem to be economy to make this of such form that it will disintegrate the furrow slice as coinpletelj' as possible. Sich lircaking of the furrow slice makes it easier for the tillage implements follow- ing the plow to tine the soil thoroughly without disturl>ing the buried sod and vegetation. A further imp<irtant advantage of the work of such plows is the increased opportunity afforded tb the soil for weathering. jjloyed for water-furrowing, etc.; the hillside or swivel plow, which is provided with a reversible mold-board, so that the team may walk in the opposite direction, but always place the furrow against the one previously turned. Another special form of plow is the double-furrow or gang plow (Fig. 4), which consists of an iron frame, usually mounted on a wheel or wheels, carrying two or more plows, one set a little to the rear of the other, and at the distance it is de- sired the width of the furrow should ))e. The sulky plow (Kig. o) has also ccnne into exten- sive use, the object of such jilows being to lessen friction and reduce the labor of the plowman. The draught of such jdows, however, was found by Sanborn to be not materially less than that of the ordinary swing plow. The tirst patent for sulky plows in America was granted to H. lirovvn in 1844, but practical plows of this type were not made until about 1804, and the manufacture of such plows is still in a state of evolution, al- though numerous forms are found on the market. The disk plow (Fig. fi), which is a comparatively recent invention, is attracting wide attention on account of its eft'ective work under certain con- ditions. The principal feature of this plow in its more perfect form is a tempered steel disk I'la. fi. ari.KV ei.ow. There are numerous other kinds of i)lows used for special purposes, such as trench or ilitching plows, which are made on the same principle as the common plow, but larger and stronger, so as to bring up a portion of the subsoil to the sur- face: or subsoil plows, Mhich have no mold-board, and merely stir and break up the subsoil, thus facilitating drainage. These plows are not used so nuich as formerly. There are also double mold-board plows, which are merely common plows with a mold-board on each side, em- FlG. 6. UI8K PLOW. 2.") tij .'iO inches in diameter, and usually set at an angle to the furrow and to the siirface so as to tirn and pulverize the soil. It is kept from clogging and assisted in pulverizing the soil by an adjustable scraper. The disk is carried by a steel framework mounted on wheels and provided with a scat for the driver and levers for control and adjustment of the plow. The idea of the use of engines and machinery to i>Iow the ground seems to have originated with David Ramsey and Tlionuis Wililgosse ia 1(J18, but the motive power they proposed to use is not made clear. Francis Moore in 17li!) first attempted to use the steam-engine for this pur- pose. The history of practical steam plowing dates from the invention of Fowler, assisted by Smith, in 18.54. The inventions along this line have included plans for engines traveling over the surface of the ground, drawing jilows or other cultivating implements along with them; engines working on tramways, ami drawing im- plements after them; engines moving along oppo- site headlands, and working implements be- tween them by means of wire ropes and station- ary engines driving im])lements also by means of wire ropes. The steam plows used most widely in Kngland belong to two classes — double-engine and single-engine or 'direct' and 'roind-alioit' (Figs. 7 and 8). Gang plows carried on wheels are usually employed in these systems, the plows being in two series facing in opposite directions
