62] COR the shells of fishes. It is cele- brated as a vermifuge, and, ac- cording to Geo.feb.oy, may be given in powder, from 10 grains to a scruple, or half a dram per day, with considerably good effect. But we doubt whether it possesses any medicinal virtues, as it is per- il' try insipid to the taste, and ope- rates merely as an absorbent earth. CORD, a combination of several threads of hemp, twisted together by means of a wheel. Cords are extensively useful for various purposes of domestic life, but more particu'arly in the rigging of ships ; in which case they are, according to their size, called ca- bles, or ropes, to which we re- fer. Hence, the manufacture of these articles has become an object of considerable importance. In the common way of making- cordage, it has been found, that, by being twisted too light, ropes v< re rendered incapable of raising weights beyond a certain propor- tion, and that, from the friction occasioned by their inelasticity, the) were neither very durable, nor always sate. Various means ave been devised to obviate ties defect, and several patents have lately been granted, {rum which we select the following. In July ];p2, Mr. James Mit- chell, of Poplar, and Blaekwall, Middlesex, obtained a patent for a method of manufacturing cor- dage on a scientific principle. It apparently consists in subdividing the twists or cylindrical parts of ropes, or cordage, and giving til em a peculiar turn, so as to make the m blend ami unite; and also to operate in such a manner that the component parts act in spiral di- r< eiaons, similar to parallels. By this mode, tin- yarns all bear to- COR gether, so that the cordage acquires-' an increased degree of tension, as well as a greater power of resist- ing fluids and friction, and also a more uniform elasticity. A patent was also granted, in January 1/ps, to Mr. W. Chap- man, of Newcastle-upon-Tyne, tor a new method of manufactur- ing ropes or cordage. The patentee describes his invention to con- sist in placing those parts that separately twist the rope and strands (each of which contains a number of yarns twisted together) at a certain determinate distance. By such means, the process of t isting is not completed through the whole length at once, but only in the intermediate space. With this circumstance, the patentee combines a mode of twisting the cord or rope itself by an arbor or shaft, perforated either through the whole or a part of its extent, and revolving round its own axis ; and which, at the same time, twists its several parts, by mean-! of separate arbors or shafts, either perforated or otherwise, each of which performs a like revolution. Thus, not only the operation of twisting the cord or rope is effect- ed, but also that of coiling it up, by the motion of the machine, while both time anil length of ground are saved, which, accord- to the prevailing mode of mak- ing cordage, are uselessly occu- pied. Another patent which we shall notice, is that granted in August. 1799, to Joseph Huddakt, of Islington, Ksq. for an improved method of forming the strands in the machinery for manufacturing cordage. The loading principle of this invention is, to give the length of the yarns composing the sti. a cecg
