The warp-threads next are drawn through the interspaces between two dents or strips of the sley or reed. This is done with a wire hook called a sley-hook or reed-hook. Two warp-threads are drawn in each space. The sley or reed is composed of a row of short and very thin parallel strips of cane or metal, somewhat like comb-teeth, called dents, fixed at both ends closely in two long, strong, parallel bars of wood set two or three or even four inches apart. There may be fifty or sixty of these dents to one inch, for weaving very fine linen; usually there are about twenty, which gives a "bier"--a counting out of forty warp-threads to each inch. Sleys were numbered according to the number of biers they held. The number of dents to an inch determined the "set of the web," the fineness of the piece. This reed is placed in a groove on the lower edge of a heavy batten (or lay or lathe). This batten hangs by two swords or side bars and swings from an axle or "rocking tree" at the top of the loom. As the heavy batten swings on its axle, the reed forces with a sharp blow every newly placed thread of the weft into its proper place close to the previously woven part of the texture. This is the heavy thwacking sound heard in hand-weaving. On the accurate poise of the batten depends largely the evenness of the completed woof. If the material is heavy, the batten should be swung high, thus having a good sweep and much force in its blow. The batten should be so poised as to swing back itself into place after each blow. The weaver, with foot on treadle, sits on a narrow, high bench, which is fastened from post to post of the loom. James Maxwell, the weaver-poet, wrote under his portrait in his _Weaver's Meditations_, printed in 1756:-- "Lo! here 'twixt Heaven and Earth I swing, And whilst the Shuttle swiftly flies, With cheerful heart I work and sing And envy none beneath the skies." There are three motions in hand-weaving. First: by the action of one foot-treadle one harness or heddle, holding every alternate warp-thread, is depressed from the level of the entire expanse of warp-threads. The separation of the warp-threads by this depression of one harness is called a shed. Some elaborate patterns have six harnesses. In such a piece there are ten different sheds, or combinations of openings of the warp-threads. In a four-harness piece there are six different sheds.