Книга или автор
0,0
0 читателей оценили
266 печ. страниц
2019 год
0+

Various
The Atlantic Monthly, Volume 18, No. 106, August, 1866 / A Magazine of Literature, Science, Art, and Politics

HOW MY NEW ACQUAINTANCES SPIN

The strictly professional man may have overcome his natural aversion to some of the most interesting objects of his study, such as snakes, and toads, and spiders, and vermin of all kinds; but people in general have always required that any attempt to force such abominations upon their notice should be preceded by a more or less elaborate and humble acknowledgment of their hideous aspect, their ferocious disposition, their dark and bloody deeds, and the utter impossibility of their conducing in any way to human comfort and convenience.

But, while admitting the truth of much that has been thus urged against spiders as a class, I must decline, or at least defer, conforming to custom in speaking of the particular variety which we are about to consider, and I believe that it will need only a glance at the insect and its silk, and a brief notice of its habits, to justify my indisposition to follow the usual routine.

Without apology, then, I shall endeavor to show that in the structure, the habits, the mode of growth, and, above all, in the productions of this spider are to be found subjects worthy the attention of every class of minds; for to the naturalist is exhibited a species which, though not absolutely new to science, was never seen nor heard of by Professor Agassiz till the spring of 1865, and which is so narrowly circumscribed in its geographical distribution that, so far as I can ascertain, it was never observed by Hentz,—a Southern entomologist, who devoted himself particularly to spiders,—and is met with only upon a few low, marshy islands on the coast of South Carolina, and perhaps of other Southern States. Its habits, too, are so interesting, and so different in many respects from those recorded of other species, that the observer of living creatures has here an abundant opportunity, not only for increasing his own knowledge, but for enlarging the domain of science. And this more especially in America; for while, in England, Blackwall and others have been laboring for more than thirty years, spiders seem to have received little attention on this side of the Atlantic.

We have now, moreover, in our observation of these insects, an incentive of sovereign effect, namely, the hope of increasing our national wealth; for to the practical man, to the manufacturer and the mechanic, is offered a new silken material which far surpasses in beauty and elegance that of the silk-worm, and which, however small in quantity at present, demands some attention in view of the alarming decrease in the silk crops of Europe. This material is obtained in a manner entirely new,—not, as with the worm, by unwinding the cocoons, nor yet, as might be suggested for the spider, by unravelling the web, but by drawing or winding or reeling directly from the body of the living insect, even as you would milk a cow, or, more aptly, as wire is pulled through a wire-drawing machine.

To the admirer of the beautiful and perfect in nature is presented a fibre of absolute smoothness, roundness, and finish, the colors of which resemble, and in the sunlight even excel in brilliancy those of the two precious metals, silver and gold; while the moralist who loves to illustrate the workings of God's providence in bringing forth good out of evil, by comparing the disgusting silk-worm with its beautiful and useful product, may now enforce the lesson by the still more striking contrast between this silk and the loathed and hated spider.

The statesman who, after a four years' war, sees few indications of a better spirit on the part of the South, and is almost ready to exclaim, "Can any good thing come out of Nazareth?" may now perhaps discern a spot, small indeed, but brilliant, on the very edge of the dark Carolina cloud; and it may not be too much to hope that, in course of time, the cords of our spider's golden and silver silk may prove potent bonds of union with the first of the rebellious States.

As to the mathematician who believes in the inborn tendency of mankind to variation and imperfection, and holds up to us, as shining examples of mathematical accuracy, the work of certain insects, and who—since Professor Wyman has shown that the hexagonal form of the bee's cell is not of original design, but rather the necessary result of difficulties met and overcome in the most economical manner, though by no means always with perfect exactness and uniformity—has fallen back upon the ancient and still prevalent belief in the precise construction of the spider's web, (which, as will be seen, really displays it no more than does the bee's cell,)—to this disappointed man of geometry and figures is now offered the alternative of either finding a new and truer illustration, or of abandoning his position entirely.

Let us, then, wait till we have seen this spider and heard his story. His story! That reminds me of another class which may possibly be represented among my readers, and whose members, in the contemplation of the domestic economy of these insects, will, I fear, discover many and weighty arguments in favor of the various opinions entertained by the advocates of Woman's Rights; for here is a community in which the females not only far exceed the males in number, but present so great a contrast to them in size and importance, that, but for absolute proof, they never would be regarded as belonging to the same species.

Here, then, is a life-size picture of our spider and of—I was about to say, his partner; but in truth it is she who is the spider, and he is only her partner. Such is the real physical, and, so to speak, mental superiority of the female, that, even if we insist upon the legal equality at least of the masculine element, we can do so only in name, and will find it hard to avoid speaking of him as the male of the Nephila plumipes, thus tacitly admitting her as the truer representative of the species. Their relative size and appearance are shown by the figures; but it may be added that she is very handsome; the fore part of her body, which, being composed of the head and chest soldered together, is termed cephalothorax, is glossy-black and covered, except in spots, with white hairs; she has also upon six of her legs one or two brushes of black hairs;—while he is an insignificant-looking insect of a dull-brown color and half-starved look, with only a few scattered bristles upon his slender limbs. He does nothing for himself, leaving her to make the web and provide the food, and even to carry him on her back when removal is necessary; but she makes up for the imposition by keeping him on short allowance and at a respectful distance, excepting when the impregnation of her eggs is necessary; and even then she is mistress of the situation, and, etiam in amoribus sæva, may afterward eat him up. But of this contrast between the two sexes, of their functions and their relations to each other, more hereafter. It is sufficient to observe that, when this spider is mentioned, and the sex is not specified, the female is always referred to.

Fig. 1. Male and Female Nephila plumipes.


When, where, and how was this spider discovered? and why is it that we have never heard of it before? To answer these questions, we must go back three years, to the 19th of August, 1863, and to the camp of the Fifty-fifth Regiment of Massachusetts Volunteers, on a desolate island a little south from the harbor of Charleston, South Carolina, and in sight of the fortress which Gillmore had just begun to strengthen by the addition of tons of Union shot and shell, till, from tolerably strong masonry, its walls became solid earthworks which nothing could pierce or greatly injure. There, at the north end of Folly Island,—scarce wider than our camp at that point, and narrower than the magnificent beach which, at low tide, afforded ample space for the battalion drill,—I found in a tree a very large and handsome spider, whose web was at least three feet in diameter.

Glad enough to meet with anything new, and bearing in mind the interest with which, when a boy, I had watched and recorded the operations of our common house and hunting spiders, I entangled him—I didn't then know it was her, so let it pass—in the web, and carried it to my tent. The insect was very quiet, and did not attempt to escape; but presently, after crawling slowly along my sleeve, she let herself down to the floor, taking first the precaution, after the prudent fashion of most spiders, to attach to the point she left a silken line, which, as she descended, came from her body. Rather than seize the insect itself, I caught the thread and pulled. The spider was not moved, but the line readily drew out, and, being wound upon my hands, seemed so strong that I attached the end to a little quill, and, having placed the spider upon the side of the tent, lay down on my couch and turned the quill between my fingers at such a rate that in one minute six feet of silk were wound upon it. At the end of an hour and a half I estimated, with due allowance for stop-pages, that I had four hundred and fifty feet, or one hundred and fifty yards, of the most brilliant and beautiful golden silk I had ever seen.

During all this operation the spider had remained perfectly quiet, but finally put an end to my proceedings by grasping the line with the tip of one of her hind legs so that it snapped. I was tired, however, and contented myself with the quantity already obtained, which now formed a raised band of gold upon the quill. This specimen is now in my possession, but has been removed from the quill to ascertain its weight, which is one third of a grain.

It is worthy of notice, perhaps, that in all this was involved no new fact, but only a happy deduction from one known ages ago; namely, that a spider, when dropping, leaves her line attached, and so allows it to be drawn from her body. Nothing was more natural than to simply reverse the position of the fixed point, and, instead of letting the spider go away from the end of her line, to take the end of her line away from her. So natural, indeed, did it seem, that my gratification at having been (as was then supposed) the first to do it was, on reflection, mixed with surprise that no one had ever thought of it before, and I am very glad to find that at least four individuals have, within the last century, pulled silk out of a spider, though of these only one, whose researches I hope to make known, regarded the matter as anything more than a curious experiment.

I had never before seen such a spider, nor even paid attention to any geometrical species; though one large black and yellow variety is, or used to be, common enough in our fields at the North. Neither had I ever heard of such a method of obtaining silk. But though my first specimen was not preserved, and a second was never seen on Folly Island, yet I was so impressed with its size and brilliant colors, and especially with the curious brushes of black hairs on its legs, that when, during the following summer, another officer described to me a great spider which was very common on Long Island, where he was stationed, I knew it was the same, and told him what I had done the year before, adding that I was sure something would come of it in time.

With leisure and many spiders at his command, this officer improved upon my suggestion, by substituting for my quill turned in the fingers a wooden cylinder worked by a crank, and by securing, at a proper distance, (between pins, I think,) one or more spiders, whose threads were guided between pins upon the cylinder. He thus produced more of the silk, winding it upon rings of hard rubber so as to make very pretty ornaments. With this simple machine I wound the silk in two grooves cut on a ring of hard rubber and parallel except at one point, where they crossed so as to form a kind of signet. Another officer now suggested and put in operation still another improvement, in the shape of the "gear-drill-stock" of our armorer's chest. This, being a machine for drilling iron, was rough in its construction and uneven in its action, but, having cog-wheels, a rapid and nearly steady motion could be given to its shaft. To this shaft he attached a little cross of rubber, and covered it with silk, which was of a silver-white color instead of golden-yellow, as in other cases. The difference in color was then supposed to depend upon individual peculiarities, but the true explanation will be given farther on. With this gear-drill-stock, upon a larger ring, one inch in diameter and three eighths of an inch in width, in a groove upon its periphery one fourth of an inch in width, and across the sides of the ring in two directions, I wound three thousand four hundred and eighty-four yards, or nearly two miles, of silk. The length was estimated by accurately determining the different dimensions of the ring where wound upon, and multiplying by this the number of revolutions of the cylinder per minute (170), and this product again by the number of minutes of actual winding (285), deducting from the gross time of winding (about nine hours) each moment of stoppage for any cause.

This was late in the fall of 1864, and, our specimens being sent home, further experiments, and even thoughts upon the subject, were prevented by the expedition against the Charleston and Savannah Railroad, and the many changes of station that followed the disastrous battle of Honey Hill. But, when I was at the North in February, 1865, a friend expressed to me his confident belief that this new silken product could be made of practical utility, and advised me to make inquiries on the subject. So, before presenting it to the scientific societies, I tested the strength of the silk by attaching to a fixed point one end of a thread one four-thousandth of an inch in diameter, and tying the other end upon the arm of an accurate balance: weights were then dropped in to the amount of fifty-four grains before the line was broken. By a calculation from this, a solid bar of spider's silk, one inch in diameter, would sustain a weight of more than seventy tons; while a similar bar of steel will sustain only fifty-six, and one of iron twenty-eight tons. The specimens were then exhibited to Professors Wyman, Agassiz, and Cooke, of Harvard University, to all of whom the species of spider was unknown, though Professor Wyman has since found a single specimen among some insects collected at the South; while to them as well as to the silk-manufacturers the idea of reeling silk directly from a living insect was entirely new. The latter, of course, wished to see a quantity of it before pronouncing upon its usefulness. So most of my furlough was spent in making arrangements for securing a number of the spiders, and reeling their silk during the coming summer. These comprised six light wooden boxes with sliding fronts, each eighteen inches wide and high and one foot deep, and containing six tin trays one above another, each of which, again, held twenty-four square paper boxes two and a half inches in diameter, and with lids closed by an elastic. Into these the spiders were to be put for transportation. Then I had made a costly machine for reeling the silk, which, however, proved of no practical value.
















Установите
приложение, чтобы
продолжить читать
эту книгу
256 000 книг 
и 50 000 аудиокниг