A TREATISE

ON THE QUALITY, MANUFACTURE, AND CHOICE OF CORDAGE, FOR MINING PURPOSES, WITH RULES AND TABLES FOR THE WEIGHT AND NUMBER OF THREADS CONTAINED IN ANY SIZE ROPE.

It is certainly very desirable, if not absolutely necessary, that every person who is intrusted with the management of a mine should possess some means of obtaining, with a degree of certainty, the quality and weight of the ropes he may have occasion to use; otherwise the lives and property intrusted to his care will be continually placed in jeopardy, and his employers be always subject to impositions respecting the charge; because in many cases (from the magnitude of the material) it cannot be weighed, and therefore its weight can only be ascertained by computation; consequently, if the agent is ignorant of the matter, the right of the adventurers will solely depend on the truth of the manufacturer's calculation.

The following tables will enable the agent to find the weight of any rope, and the ensuing remarks will help his judgment respecting the quality thereof; being far the most important part of the subject.

There are various methods of discovering the quality of hemp; but as miners have seldom an opportunity of inspecting the article in this stage of preparation, we shall pass on, and show how it may be proved after its having been completely manufactured.

The first thing that commands our particular attention is, the size of the yarn or thread of which the rope is composed. There

is a certain gauge or standard for this, known among ropemakers by the terms, sixteens, eighteens, twenties, &c., which means 16, 18, or 20 yarns in the strand, or third part of a rope 3 inches in circumference. The following table shows the weight of the different sizes of yarn before it has gone through the operation of tarring.

Now the true standard size for shroud-laid rope is twenties,* and it is of consequence that agents should give their orders accordingly, and afterwards be assured that their ropes have really been made with yarns of this gauge.

In order to prove this, first, girt the circumference of the rope, then count the yarns in the strand, and, lastly, refer to the table (page 403), and note if the number corresponds with that standing in the proper column, opposite the dimensions of the rope.

Manufacturers have many inducements for spinning their yarn large. First, it is less expensive, for it requires no more time to spin a large yarn than to spin a small one, and 16 or 17 yarns (in their way) will answer the end of twenty. Secondly, in large yarns, inferior or refuse hemp can be spun, which cannot be done in yarns of a smaller size; and this consideration, if there was no other, should cause the agent to be exceedingly particular in having his rope made of standard yarns; and let it be remarked, that although a rope made of sixteens or eighteens will be nearly equal in weight to another made of twenties, yet by no means will it be equal in strength, even if made of the very same kind, or indeed of superior hemp. This is too plain a truth to need any illustration: for though it may be argued that what is wanting in number is made up in bulk, yet it will support an equal weight no more, in proportion, than a body of raw hemp the size of a cable will be as strong as the cable itself.

By inspecting the table (page 403), it will be seen that the

* Of which it is shown in the preceding table that 170 fathoms weigh only 3 lbs. 8 oz., or 3lbs.

strand of a 16-inch capstan-rope made of twenties contains 569 yarns, but if made of sixteens, only 455 yarns; making a difference in the whole rope of 342 yarns.

We shall now give a plain and expeditious, though infallible, method, of proving the quality of hemp and yarn, viz., from the end, or fag, of the rope cut several of the yarns in fathom lengths, each of these (standard size) should suspend, or bear up separately, 70 pounds weight at the least.

Regard must next be paid to the last part of the manufacture, called the lay, or twist, of the rope; and this should undergo a strict examination, as much depends on the skill and attention of the manufacturer in this part of the process; for it is very possible that the best materials may be used, the yarn spun of the proper size, and with the greatest care, and yet the rope be very defective, and by no means fit to be depended on. This may be easily discovered when the rope is laid in a straight line; then, if either of the strands is observed to mount or fall,* that is, rise above or sink beneath the others, in any degree, the rope has been crippled, or inevitably spoiled; for if the former case, of one strand rising, in the event of trial, that strand will be found to bear little or none of the weight, when the other two will break; and in the latter case, of one strand sinking, that strand will break before the other two have been brought to the strain, or have borne any considerable part of the weight.

These great defects in cordage are too often to be found, and almost as often pass unobserved; but they may always be de

* This fault or defect is known among ropemakers by the term "pinch,” and as the remedy occasions a great deal of trouble and delay, it is too often suffered to pass, especially as few persons are able to detect it, or are aware of its injurious tendency.

There are many casual occurrences whereby ropes are exposed to injuries in mines, out of the common course of working. We may notice an instance or two, viz., inattention or ignorance in taking them from the coil when new; they should always be taken out the contrary way from which they were coiled in; that is, if a capstan rope is coiled into a wagon, the uppermost end should be put down and drawn from the under part of the carriage: also, in small cordage, the inward extremity of the rope should be taken and drawn through the aperture of the reel. The general disproportion of capstan gear in mines has a most destructive effect on the ropes; the sheaves or pulleys, as well as the barrel, of the capstan being considerably too small; indeed there is still room for much improvement in this part of mining machinery.

tected by a close inspection, and thereby many of the serious injuries and fatal accidents which so often take place in mining, be happily prevented.

We shall close these observations after remarking, that as nearly all cordage used in mining is much exposed to the alternate influence of sun and moisture, which tends greatly to accel erate its decay, it ought by all means to contain a greater quantity of tar than is generally used. The common rule is 1 to 5, or 1 to 6; but the proportion of 1 to 41, or 1 to 5, would be much better: but we recommend this increase for standing ropes only, such as capstan-ropes, &c.; as from the comparative unfrequency of their use, and the length of time they endure, are equally liable to injury from mould and decay, as from strain and friction.

The common practice of tarring the surface of the rope after it has been manufactured is of very little service: the way we recommend is, by reducing the ordinary weight suspended to the lever, during the process of tarring the yarn in the manufactory, when it is drawn in a body from the heated coppers through the knipper, whereby the tar being lodged in the internal part of the rope cannot fail of preserving it under all circumstances.

The following rules, examples, and tables will be found plain, convenient and correct.

TO FIND THE NUMBER OF THREADS IN A SHROUD-LAID ROPE.*

Rule.-State the question as in direct proportion, square the first and third terms, multiply the second and third terms together, and divide the product by the first.

EXAMPLE.

How many standard yarns, or threads, are there in a 14-inch capstan rope?

* The term "shroud-laid" is used to distinguish a rope of three strands or parts from another of nine strands, which is termed "cable-laid." The latter may be said to be 3 shroud-laid ropes twisted together. It is seldom that any other but three-strand ropes are used in mines.