The tying up of parcels in paper is an operation which is seldom neatly performed by persons whose occupations have not given them great facilities for constant practice. Whether the paper be wrapped round the objects, as is the case usually when it is much larger than sufficient to enclose them, or merely folded over itself, as is done by druggists, who cut the paper to the required size, it is important that the breadth of the paper should be no more than sufficient to enable it to be folded over the ends of the object enclosed, without passing over the opposite side: it is impossible to make a neat or close parcel with paper which is too broad; excess in length may be readily disposed of by wrapping it round; but excess of breadth should be cut away. With regard to turning in the ends, the mode adopted by grocers is the best. The most common cause of failure in parcels is their being badly corded; we will, therefore (however unnecessary the description of so simple a performance may appear to those already acquainted with it), describe the most readily acquired mode of cording. [Illustration: _Fig. 21._] Let a single knot be made in the end of the cord, which is then passed round the box or parcel. This knotted end is now tied by a single hitch round the middle of the cord (_Fig. 20_) and the whole pulled tight. The cord itself is then carried at right angles round the end of the parcel, and where it crosses the transverse cord on the bottom of the box (_Fig. 21_), it should (if the parcel is heavy, and requires to be firmly secured) be passed _over_ the cross cord, then back underneath it, and pulled tightly, then over itself; lastly, under the cross cord, and on around the other end of the box. When it reaches the top it must be secured by passing it under that part of the cord which runs lengthways (_a_, _Fig. 20_) pulling it very tight, and fastening it by two half hitches round itself. The great cause of parcels becoming loose is the fact of the cord being often fastened to one of the transverse parts (as _b_, _Fig. 20_) instead of the piece running lengthways, and in this case it invariably becomes loose. The description may perhaps be rendered clearer by the aid of the figures, which exhibit the top and bottom of a box corded as described. The cords, however, are shown in a loose state, to allow their arrangements to be perceived more easily. VII. ON THE OPERATIONS AFFECTING WATER.