It may perhaps be necessary in some cases to wash the fabric under examination, lest in what is termed the “getting up for the market,” some animal matter or size might mislead. But the jury ought to be acquainted with all such difficulties, and they should state the method they took for investigating them. The microscope is of great use in the detection of adulterations in most vegetable substances. § Every object produced is subject to certain defects, and possessed of certain excellences: these should be clearly enumerated. Whenever such statements are expressed by numbers, the information will be more satisfactory. Thus, in cutting tools, as applied to various metals, it is very important that the angle at which the tool is applied, should be stated: it is also necessary to state the angle which the edge of the tool receiving the shaving cut off, makes with the surface cut. The velocity of the tool in cutting should be stated, also the names of the fluids, if any, used in cutting. The durability of woven fabrics, as well as of a great variety of other manufactured articles, is a most essential quality, on which, combined with the price, their chief value to the customer depends. It is very desirable that the jury should find satisfactory means of testing this most important character, which is not discernible, even by the most curious and instructed spectator. The knowledge of the weight required for tearing asunder any woven fabric, as a ribbon, a stay-lace, tape, &c., together with the breaking weight of their individual threads, and the number of these threads in an inch, may in some cases be very valuable, especially in coarse articles, such as sailcloth, sacking, &c. In other cases, the articles may be submitted to twenty or thirty washings and dryings, during which it may repeatedly be examined. The greatest change will most frequently occur on the first washing, which removes the dressing. § In many articles the durability of different parts varies considerably. In some cases one part will wear out, if replaced, many times before the remainder of the article is at all injured by use. In all such cases the jury should adopt such rules as the following:— Examine the durability of each part, and also the difficulty and the expense of replacing it when injured. Examine also, for the same purpose, what parts are most exposed to injury or destruction by accident. Examine also the _relative_ expense of putting the article in a working state when first purchased and brought home. These rules will be best understood by an illustration. Let us suppose a jury to be examining the relative merits of several cottage stoves for cooking. Of course the first inquiry will be as to which admits of the best performance of the operations of— Boiling, Baking, Stewing, Supply of hot water, Roasting, Ironing, Broiling, &c.