ENID
619
ENSILAGE
the wood between them being cut away. In metal-engravings the plate, having been inked and wiped on the surface, keeps the ink only in the hollowed lines, from which it is conveyed to the paper by the pressure of the printing-press. In wood-engraving only the raised part of the block is inked, by means of a roller, and it prints as a raised type.
The metal most commonly used for engraving has been copper; but during the 19th century steel was largely used on account of its hardness, which enables it to stand the wear of printing and to throw off a far larger number of impressions than could possibly be got from a copper-plate. Steel, however, is less readily engraved than copper, and the finished engraving is thus apt to be not so good. By a late invention the surfaces of copper-plates are protected by a very thin coating of steel, placed upon them by an electric battery, which enables them to give a larger number of good impressions without being worn. Zinc-plates have also been used for etchings. In line-engraving the main tool used is the burin or graver, a small bar of steel, pointed at one end and with the other fixed in a rounded wooden handle. This burin is held between the engraver's thumb and forefinger and pushed forward by the pressure of the palm on the handle, and cuts upon the plate of polished metal a line, broader or deeper according to the pressure and the angle at which the burin is held. In etching the plate is coated with a thin, transparent surface or ground that acid will not eat. The plate is then smoked black, so that the lines drawn by the etcher will show the shining metal underneath. The design is drawn with an etching-needle — a sharp steel point in a handle. The needle merely takes away the ground, showing lines of the bare metal ready to be acted on by the acid. The back of the plate is coated, to protect it, and the plate is put in a nitric-acid bath. The acid attacks and corrodes or eats the metal along the lines drawn. When the lines which are to be the lightest and palest in the etching are bitten, the plate is taken out, and these lines covered with a varnish which keeps the acid from eating them any deeper. Then the plate is put back for the acid to eat the other lines out more deeply, till the etching is finished. What is called soft-ground etching is simply another method (of which there are many) of drawing the design. In mezzotint engraving the plate is roughened— raising a "bur" of small metal points — so that if the plate were then inked and printed it would yield a uniform black impression. The mezzotinter draws his design and then scrapes away all but the lines he wishes to appear black in the printed engraving. Engraving in recent times has
suffered much because of the work done by photographic processes. The beauty of what are known as photogravures or heliogravures, reproducing paintings, drawings and photographs, makes it likely that this process will altogether take the pla^e of engraving. See WOOD-ENGRAVING, LITHOGRAPHY, PHOTOGRAVURE; also Etcher's Handbook^ by P. G. Hamerton; Ottley's Early History <?/ Engraving; and Bryan's Dictionary of Painters and Engravers.
Enid, county-seat of Garfield County, Oklahoma, 50 miles from El Reno. It is located in a good agricultural region, in which the leading crop is wheat. Its industries include railroad-shops, flour-mills, a brick-works, yeast, broom and ice-factories. It has good schools, a fine courthouse and substantial business-blocks. The city was established in 1893, a^ ^ne opening of the Cherokee strip, and has grown steadily. It has the service of three railroads and a population of 15,799.
En'silage or silage, the general name given to green crops, especially corn, packed in enclosures constructed for that purpose called silos, to be fed to stock. The practice of thus preserving gr®@m crops for fodder originated about iSo©, and in the United States about 1875.
Silos are quite simple in construction. They may be built of wood, and so are comparatively inexpensive. The essential points to be observed in their construction are (i) to have the walls as smooth as possible inside, (2) to have few corners, preferably having it round or square and. (3) to have them as nearly air-tight as possible. If built of wood, the walls may be coated with coal-tar.
In filling the silo with corn, the entire plant is taken at maturity, just before the leaves begin to lose their moisture. It is cut into pieces one or two inches long and then closely packed in. If the silo is airtight and the corn is evenly and tightly packed, there is little danger of its spoiling. If the crop is unusually dry, a considerable amount of water should be poured upon it while it is being packed. The layer at the top may be kept from spoiling by covering it with eight inches of chaff or cut-straw until ready for use.
It is calculated that food equivalent to four tons of hay can ordinarily be produced from one acre of corn. This makes corn preserved in a silo a profitable crop, especially as it can be so compactly and economically stored. Though corn is the most satisfactory crop for ensilage, red clover, oats, rye, alfalfa, millets and cow-peas are also used. About one cubic foot of silage (30 or 40 pounds), along with other foods, is considered the right quantity per day for one cow. Though silage has been successfully fed to horses, sheep and beef-cattle, it is especially suitable for
