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.
In March, with these and other real or fancied adjuvants, (some of which proved even less useful and trustworthy than the machine,) but, above all, with a determination to put this matter to the test of actual experiment, I rejoined the regiment at Charleston, which had just fallen into our hands. It was not until April, however, that we were so situated that I could make any attempt to get spiders. Of course it was not expected that the full-grown ones should be found at that season, but the eggs or young should be abundant where the spiders had been in the summer.
Before recounting my adventures in pursuit of my spinster friends, it may be well to say a few words of the locality which they inhabited.
Fig. 2. Map of Charleston and Vicinity.
Charleston stands upon the extremity of a narrow peninsula, between the Cooper and the Ashley Rivers. Charleston Harbor, supplied by these and some smaller streams, lies between Mt. Pleasant and Sullivan's Island on the northeast, and James and Morris Islands on the southwest. One cannot but be struck with the resemblance, so great as to be almost symmetrical, between the two sides of the harbor. Mt. Pleasant and James Island are quite high land,—high at least for the coast of South Carolina,—and are separated from the mainland, the one by the Wando River, the other by Wappoo Creek; while Sullivan's Island, where stand Fort Moultrie and other Rebel batteries, corresponds almost precisely to Morris Island, both being low and sandy, and being, as it were, bent inland from the sea, with sharp points looking toward the city, their convex shores forming a rounded entrance to the harbor. Extending southward from Morris Island, and separated from it by Lighthouse Inlet, is Folly Island; and in exact correspondence to the latter, north of Sullivan's Island, and separated from it by Breach Inlet, is a similar sand-ridge called Long Island. But now occurs a difference; for while between Long and Sullivan's Islands and Christ's Church Parish is an immense salt marsh intersected by creeks, but presenting an unbroken surface, in the midst of the corresponding marsh between Morris and Folly Islands and James Island is a group of low wooded islands, the largest of which lies opposite the upper or north end of Folly Island. To this no name is given on the maps, nor is it even distinguished from the marsh. It is, however, completely surrounded by water; and, though this is in the form of creeks neither wide nor deep, yet the peculiar softness of the mud, and the absence of any landing-place except upon the side toward Folly Island, render it almost inaccessible.
To this narrow strip of land, not three miles in length, was given the name of Long Island,—perhaps by our own troops, who knew nothing of an island of the same name north of the harbor; and in case it is found that no other name belongs to it, we may properly avoid a confusion, and christen it Spider Island, in honor of the remarkable insects for whose especial benefit it seems to have been made, and which, with the exception of the mosquitoes, are its sole inhabitants.
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