There are various devices for securing the wire to the end posts, but the commonest method is to wind them about the post once and secure them with a staple, or twist the end of the wire back upon itself, forming a loop. The wires should be drawn taut to prevent sagging with the weight of fruit and leaves. In order to allow for the contraction of the wires in winter, some growers loosen the wires after harvest and others provide some device which will relieve the strain. The Yeoman's Patent Grape-Vine Trellis is a simple and effective lever-contrivance attached to each wire, and which is operated to loosen the wires in fall and to tighten them in spring. The end post is sometimes provided upon the back with a square-headed pin which works tightly in an inch and a half augur hole and about which the end of the wire is wound. A square-headed iron wrench operates the pin, while the tension of the wire around the side of the post keeps the pin from slipping. This device is not durable, however. An ingenious man can easily contrive some device for relieving the tension, if he should think it necessary. As a matter of practice, however, the wires soon stretch and sag enough with the burden of fruit and vines to take up the winter contraction, and most growers do not release the wires in fall. It will be found necessary, in fact, to tighten the wires and to straighten up the posts from year to year, as they become loose. It is always a profitable labor to tamp the ground firmly about all the posts every spring. The wires should always be kept tight during the growing season to prevent the whipping of the vines by wind. This is especially important in white grapes, which are discolored by the rubbing of leaves and twigs. Unless the vines are very strong it will be necessary to stretch only one wire the first winter. Trellises are often made of slats, as shown in Fig. 18, but these are always less durable than the wire trellises and more expensive to keep in repair; and in the older portions of the country, where timber is dear, they are also more expensive at the outset. They catch the wind, and, not being held together by continuous strands, are likely to blow down in sections. Fuller particulars concerning the styles of trellis are given in the discussions of the different systems of training.