If you can picture to yourself a mass of pure and yellow gold, which not only reflects the light as from a smooth and polished surface, but which has all the depth and softness of liquid amber, you may realize in some degree the wonderful appearance of a sheet of spiders* silk as seen in the sunshine ; and even in the shade its luster is greater than that of gold. But to compare the silk with gold is to tell only one half of the story ; for the same spider yields silver as well, so that you may draw from its body a thread of gold or a thread of silver, or both threads together; their union giving silk of a light yellow color. These two differently-colored silks are drawn from two different parts of the spinning organ, which wiU be described hereafter; and not only are their colors thus distinct, but also their other physical properties ; for the yellow is elastic, and may be stretched slightly and regain its former length, while the whi|e is inelastic, and at once crinkles up when tension is removed during the process of drawing it from the spider. The two kinds of silk are employed also in the construSion of different parts of the web; but that has been sufficiently described elsewhere. Beauty and strength are natural partners, and we do not look in vain for the latter quality in spiders' silk. It is indeed \ something prodigious as compared with even the strength of metals. A bar of iron one inch in diameter will sustain a weight of twenty-eight tuns; a bar of steel fifty-eight tuns, and, according to computation based upon the fact that a fiber only one four-thousandth of an inch in diameter will sustain fifty-four grains, a bar of spiders' silk an inch in diameter would support a weight of seventy-four tuns. disadvantages of spidees' silk. Aside from its excessive fineness, the only thing to be said against the silk is the small quantity .which a single spider will yield, as compared with the production of a silk-worm. And when it is admitted that the latter spins big cocoon which yields, upon an average, three hundred yards of silk, weighing about three grains, while the average length which can be reeled from a spider at one time is only one hundred and fifty yards, which is so much finer as to weigh but one-twentieth of a grain, our quantitative comparison looks rather discouraging and lessens-the satisfaction we had derived from the previous comparison of quality. But there are several other facts to be considered which tend to greatly reduce this discrepancy between the production of the two insects; some of these relate directly to the one and some to the other. Let us first reduce the silk furnished by the worm from its apparent to its real amount. Three grains represents the average gross weight of silk yielded by one cocoon ; but the fiber is so covered with gum which would materially interfere with its manufacture that it has to be cleansed by prolonged boiling in soap and water, which process costs each cocoon one quarter of its weight, leaving the real amount of available silk supplied by each worm, two and a quarter grains; but even this is forty-five times the yield of a single spider, and any practical inquirer will not gain much comfort from the comparison. Having now placed the worm's production in its true light, what can we say of the spider to increase the statement of its yield ? So far from being destroyed, as is the worm, for the sake of one cocoon, and thereby being prevented from further service in way of laying its eggs, the spider is not at all injured by the reeling process and after a day or two of rest, is ready to yield us a second hundred and fifty yards, more or less, and then a third and a fourth, until it has been reeled from, say twenty times in the course of a month, nor is this probably the limit of their capacity, under favorable conditions, but it will be seen that, even granting it to be so, and its season to be limited to a month, the spider of a whole season i s twenty times as valuable as the spider of a single day, and the total yield would be about three thousand yards weighing just one grain. Now, the worm yields only two and a quarter times as much as this, and that is the end of it. Like tho swan, it expends all its life in a last effort; but the spider, like the canary, does something every day, and when no longer able to produce silk, can provide for future generations by laying five hundred or more eggs. Admitting then that a worm yields two and a quarter times as much as a spider, what is the number of each required for a piece of woven silk ? A yard of silk varies greatly in weight, and somewhat too in quality, and of course in cost; the quality we cannot here consider, but as to weight and cost, a cheap silk at two dollars and fifty cents weight from one half to three fourths of an ounce per yard. A rich silk at from six dollars to ten dollars weighs two ounces or a little over. And between these two, the ordinary grades in which the majority of people are interested cost from three dollars to five dollars per yard,and weigh from one to one and a quarter ounces. An ounce is four hundred and thirty-seven and a half grains (avoirdupois), and as each spider yields one grain, it will require, in round numbers, four hundred and fifty to produce a yard of silk ; or fifty-four hundred for an ordinary dress-pattern of tw;elve yards. The number of worms required for the same is to be ascertained by dividing those figures by two and a quarter, which makes, in round numbers, two hundred worms for a yard, and twenty-four hundred for a dress. And now supposing (for the sake of comparison) that each spider costs as much time and trouble and money as a worm, and that, therefore, a fabiic of spiders' silk costs two and a quarter times as much as one of ordinary silk, that fact by qo means indicates that the former is not worth having. Honey costs more than molasses, but every body of taste thinks it worth the difference ; a steel knife is all very well, but a silver one is worth the difference in cost to all who can afford to pay it. A cotton or woolen dress is not to be de-3pised by any one, but every woman prefers a silken gown, md counts the increasod price as small compared to the greater satisfaction it affords ; and now, so far at least, as we can judge; as honey is to molasses, as silver to steel, as silk io cotton, so is the product of our spider to that of the worm; and the superior beauty, and elegance, and delicacy of the fabric will, no doubt, more than compensate for the difference in its cost. machinery. First catch your spider, is a necessary preliminary, and although this matter properly belongs to the last division of Dur subject, it may be well to quiet the apprehensions of any one who suddenly recollects the big body, and long legs, and sharp jaws of the Nepliila plumipes, as elsewhere figured, and fears that it is an untamable creature which will resist an attempt to abstract its silken stores. I will leave the complete removal of this apparent obstacle until we come to consider the spider itself in all its relations, and merely say now that it seldom tries to escape or to bite ; that you have only to get its body between thumb and finger so that two legs are turned backward, to be perfectly safe from injury by its jaws. After many trials, the contrivance which I have adopted consists of two large corks, a bent hair-pin, two large common pins, a bit of ca and a bit of lead. One cork serves as base. Its bottom is loaded with the lead, and one half its top is beveled off at an angle of forty-five degrees; upon the oblique surface so formed is fixed the piece of card, its upper edge projecting an eighth of an inch ; into the remaining half of the upper end is cut a broad and shallow groove, and upon each side of this groove, at the middle of its length, the two pins are stuck into the cork, so as to be about an inch apart ; and now when the insect is held with the legs behind the back and laid upside down into the groove, the projecting shoulders of the abdomen bring up against the edge of the card, and the legs are kept in front of the two pins. The upper cork is rounded and smoothed at its smaller end, and a hair-pin is pushed obliquely through the lower corner of the larger end so as to form an angle of forty-five degrees with the lower side; one or two tacks will retain the pin in its place ; at the distance of a quarter or third of an inch from the cork, the pin is bent outward on both sides so as to double its width, and then stroightened. Now push the ends of the pin down between the card and the first cork, with the munded end of the second cork projecting over the card. This may be done with the left forefinger, while the first cork is held between the second finger and thumb ; the spider's abdomen is now put through the opening formed by the pin on each side, the cork above, and the cork below ; its abdomen rests in th-e groove, the shoulders come against the card, the upper cork is pressed down so that the narrow part of the pin embraces the pedicle; the legs being set free, fly up and embrace the rounded upper cork, the lower one is fixed upon a screw, turned around so that the abdomen of the spider points to the right; and we are ready to begin the reeling process. The reel is either a cylinder or ring of some smooth substance as hard rubber, or consists of a set of radii set into an axle, and having their ends bent at a right angle and en-' eled so as to present an even surface to the delicate silk. The reel I used had radii about three inches in length ; this made the whole diameter six inches, and of course at every revolution eighteen inches of silk were reeled upon it; the motion could be quite rapid, and if steady, one or even two feet of silk could be drawn each second, so that a very few minutes would suffice to exhauk the day's supply of a spider. The thread of a single spider cannot be drawn from a reel In order to obtain a compound thread of such size as to permit us to unwind it from the reel, we have only to arrange a . large number of spiders, and carry their combined threads upon the reel; by well-known mechanical contrivances the reel itself (which must not be a slender spindle) may be madd 71 to revolve in two directions, soastotwist the thread properly, and the there seems to be nothing to hinder carrying the silk directly from the spider's body to the sewing machine or the loom, for there is no gum to be removed, and its natural colors are beyond the capability of art. The spider can retard the flow of silk from its spinners by strongly pressing them against each other, but if the reeling is regular it cannot wholly prevent it. Under the head of disadvantages we must include two very unpleasant facts ; 1st, that the young devour each other to such an extent that, as a rule, only a very few out of the several hundred hatched in every cocoon ever reach the age when they separate' and build isolated webs; and, 2d, that the female spider is apt to devour her partner sometimes before, but more often after the impregnation of the eggs. The latter fact is not of so much consequence ; for the females are the spinners, and are always in the majority, not only in the number but also in the size of the individuals (the female being about 125 times as large as the male), and the males can be easily protected. But the terrible destructioii which, in a state of nature, seems necessary in order that a portion shall grow at all, is a very serious obstacle in the way of any increase of the species. This killing of each other, however, is not, apparently, from malice but from hunger, and both experiment and inference indicate that it may be almost entirely prevented by supplying the young and growing spids with suitable food. Each cocoon spun by the parent spider contains from five hundred to a thousand eggs, all of which hatch, generally in the course of a month. For several days, and even weeks, they remain huddled together in the cocoon, and whatever growth they have during that time, aside from absorption of moisture from the air, must be at the expense of the community; nor can it be well prevented. But after this time has passed, and they begin to c ome forth, either singly or in parties, and spin their little lines over the leaf to which the cocoon is attached, they may be in a great measure prevented from further cannibalism by putting in their reach drops of blood or crushed flies,*'ior very minute flies, or bugs of almost any kiad. If large numbers of them are to be reared, a special apartment should be arranged for them; each cocoon should be attached to the top of a wire frame of, say a foot in hight and nearly the same diameter, which must stand in a shallow dish of water, lest the spiders travel about the room and collect in great numbers at the top, where they could not be cared for. They will spin at first an irregular common web, and eat together from whatever food falls upon it. As they grow larger they may be separated by inverting another frame over the first; for they always ascend. After several weeks, they suddenly change their instincts; and from living together in some sort of fellowship, which really does not seem to be imcompatible with their peculiar style of eating each other up, they attempt to isolate themselves, and to make each for itself its own web, which is now geometrical, like that of the full-grown spiders; and as they now need more room, and will jealousy resent any trespassing upon their particular territory, it is time to remove them to the frames, which will be described in the following section. It is impossible to say how large a percentage may by this plan be reared from one cocoon; but the fact that two or three out of every hundred have been saved at a first trial, under very favorable conditions, show what may be expected of a plan like the above systematically conducted upon a large scale. As to the food of the young, there are some substances which breed the smaller kinds of flies, and which could be kept in a place communicating with the outer air in another room; but covered with fine wire netting. This would exclude the larger species, but would admit the little ones to deposit their eggs upon the meat, etc.; and the flies produced therefrom could enter the apartment. The growing spider, like the worm, casts its skin several times before reaching its full size, and in both the operation is attended by some danger. It is, no doubt, a disadvantage, that the spider, in moulting, is obliged to draw eight such very long legs from their old skins ; but although the legs may be occasionally pulled off in the process, yet they generally separate at the second joint from the body, and thereby no blood is lost; and, moreover, although each pair of legs has its appointed office, they act vicariously. To off*set the liability to injury in consequence of their more complicated structure, the spiders are not known to be subject to diseases, such as have so terribly destroyed the worms of late years ; but we cannot be sure that some maladies will not follow their domestication.—B, G. Wilder, M. D., in the Galaxy for July. The Ixtle Fiber. The following is a letter from Hon.J.McLeod Murphy to the Commissioner of Agriculture, accompanied with three skeins of the ixtle fiber, Bromdia sylvestris, each produced from single leaf, of which a single plant might average twenty We extract the substance of this letter from the " Report o Department of Agriculture" for May and June. " First of all, before I describe the plant and the method o its cnltivation, I beg to call your attention to the extraordina ry length and strength of the individual fibers, their suscep tibilityof being divided almost infinitesimally without break ing, their flexibility without kinking, and the readiness witl which they receive and hold vegetable or chemical dyes with out being impaired. Since my return from Mexico, I hav( had little or no opportunity of testing this plant practically but some samples, such as I send you, were given to an olc and experienced maker of fishing tackle, and he does not hesitate to pronounce the ixtle fiber as superior, in every respect, for the manufacture of trout and other fishing lines, not only account of the readiness with which it can be spun, its extraordinary strength, but its perfect freedom from kinks when wet. The only secret, if there is one, consists in the preliminary precaution of boiling the fiber (as you have it here) before twisting it. In this one respect it will supersede the use of silk. " Apart, however, from its use as a thread, I hazard nothing in saying that it forms the best paper stock that can be obtained. I speak now in reference to the imperfect, withered, rejected, and dried leaves, from which the fiber cannot be conveniently extracted by the indiff*erent mechanical means that the Indians employ. Although I have no samples of paper made from this source just now at hand, yet I can assure the department that several magnificent samples of paper for banking and commercial purposes have been made by manufacturers in the Eastern States, from the dried leaves of the ixtle plant, brought from the neighborhood of Tabasco. " The samples of fiber I send with this were obtained by the nu)st primitive means, viz., by beating, and at the same time scraping, the leaf of the plant (in a green state) with a dull machete. Then, after the removal of the glutinous vegetable matter,it is combed out and rubbed between the knuckles of the hand until the fibers are separated. The next step is to wash it in tepid water and bleach the skeins on the grass. This is the method pursued by the Indians on the isthmus of TJehuantepec ; and the average product for the labor of a man is from Jour to five pounds per day. " It is scarcely necessary to tell one so well informed as yourself, that this spontaneous product is the Bromelia sylvestris, which differs,in some respects, from the Agam Americana, the pulque de magmy, and Agave slsalana, of Campeche; a difference arising solely from soil and climatic influences. The name ixtle is given to that species which is characterized by the production of the long fiber ; and chiefly because the leaf, being shaped like a sword, has its edges armed with piickles, similar, in fact, to the weapon formed from itdi, or obsidian, used by the Aztecs. Hence the term. The pita, on the other hand, although obtained from a variety of the same plant, is a coarser and shorter fiber, which grows in the tierras templa-das. The name comes from the wordpYe5, which is given to the plantations of the pulque plant in the uplands of Mexico. But the peculiarity of the ixtle is, that it grows almost exclusively on the southern shore of the Mexican gulf, or in what is known as the 'sota vento,' that is to say, between Al-varado and Tabasco, and extending as far inland as the northern slopes of the dividing ridge which separates the Atlantic from the Pacific. The points generally selected for its culti-I vation are the edges of a thick forest, for which the small undergrowth is removed by cutting and burning. The roots of the plants are then set out at a distance of five or six feet apart; and at the end of a year the leav.3s are cut and 'scraped.' The chief object is to obtain a constant shelter from the rays of the sun, which would otherwise absorb the moisture and so gum the fibers together as to make them inseparable. " The average length of the leaf is six feet, and the time to cut it is clearly indicated by the upward inclination it makes. In other words,the radical leaves cease to form curved lines with their points downward, but stiff*en themselves out at an angle, as if to guard the source of efflorescence. When the ixtle is young its fibers are fine and white,but as it grows in age they become longer and coarser ; and in a wild state the thorns are very numerous, but by cultivationthey are diminished both in size and number,and in many instances there are none at all. Where any quantity of leaves require to be iiandled,a pitchfork would be very useful,especially if gathered for paper stock. A few days after cutting, the sun would dry them out, the thorns would drop off", and then they could be easily baled. Independent of the great value which the ixtle has for textile fabrics, and for paper, it possesses many valuable medicinal properties, to whi.ch I need not allude. It requires no labor to cultivate it, and no insect is known to feed upon it. It grows Everywhere in the primeval forests of the Gulf coasts, and, in my opinion, is far superior to any of the textile fabrics. But as yet no mechanic has succeeded in devising a means of effectually extracting the fiber, and until this is done, I presume that its real commercial value will remain unappreciated. " You will readily discover the superiority of the ixtle over the jenein of Cuba,or the hemj) which comes from Sisal and Campeche." Ocean Telegraphy, j/Telegraphy may, with propriety, be considered one of the branches of engineering, and is peculiarly of modern development. A clever writer says that it may be read by each of the five senses. On land lines each signal is made by suspending the flow of the electric current for two different intervals of time, called " dots and dashes "—the use of which in diff'erent orders,constitutes the alphabet of the telegraph. When they are printed they are read by sight,but ordinarily the operator reads them by sound,as easily as the musician reads the letters of the scale by the same sense. If the operator has no instrument he will grasp the wire in his hands,and read the signals by feeling the intermissions of the flow of the electric current. In like manner, by placing the wire across his tongue, he can "taste " the same iirtermission (but this is a dangerous experiment). And it is said that the electricity can be made to dissolve a chemical and produce a pungent odor in the telegraphic alphabet, which can be read by "smelling," but for this I do not vouch. I believe that the method ol signaling through the Atlantic cable is known in detail but few persons. The operation is exactly reversed from that on the land lines. The gutta-percha, cov ering of the copper wires under the pressure of a great depth )f water, becomes an absorbent of the electricity which is be-ng sent through them to the extent.of 90 per cent. The first Dortion of the electric wave of 10 per cent crosses the ocean 1,700 miles) in two seconds, and it woiildbe followed by a suc-;ession of waves, from the restoration of that portion of the electricity which has been absorbed by the gutta-percha in impulses, and the signal would be repeated like echoes, and pro-luce not only confusion but great delay. To remedy this, Proffessor Varley introduced a key, which sends alternate curvets, positive and negative, at such intervals as allow the first ?\ave of 10 per cent to pass forward, and then that portion ab-jorbed by the covering is neutralized by its opposite, and the iable is cleared for the transmission of a second pair of currents, rhe battery used is a very small one (three of Daniells cups), md the signal being only 10 per cent of this small current, is powerless to move any of the other instruments in use on land, rhe instrument used consists of a minute polarized needle, suspended on a single strand of a spider's web, or one from the silk worm. In the middle of this minute needle is placed an ilmost microscopic mirror, which reflects a single ray of [ight from a powerful lamp. The currents of electricity 3ff'ect this needle alternately to the right and left, for a space Df time corresponding to that occupied in the signal on the land line, the same kind of alphabet being used in both cases, rhe receiver (not operator) sits in a dark room, and the small mirror reflects the ray of light upon a piece of white paper before him, on which a black line is drawn, to the right and left of which the light is altern9g;ely reflected. The receiver reads these signals by " sight," and transmits them to another person, placed outside of the dark room, by means of an ordinary instrument. A short time since. General Reynolds told me that he had sent a message, Without either wire or cable, ninety-two miles, across an arm of Lake Superior, by means of the Heliotrope or mirror, and on the return of his messenger (who had been sent with a written coi)y) he found that the Heliotrope message had been received, understood and obeyed. He had two assistants, who had been telegraphic operators, who had for a whole summer been amusing themselves in talking to, each other with these instruments, though they were stationed ten, twenty or thirty miles apart. When the rebel General Morgan made his great raid through Indiana and Ohio he captured one of my operators, and compelled him to telegraph in Gen. Lew Wallace's name, to Cincinnati, asking how many regular troops there were in that city, Morgan read by " sound," and therefore the operator did not dare to intimate that he was under duress, and could only venture to add an extra init'al to his own signature. The receiving operator at Cincinnati knew that Morgan was in that neighborhood and suspecting,fromthe extra initial letter,that all was not right replied, greatly exaggerating the force of regulars; and the consequence was that Morgan changed his route to a circuit of twenty miles beyond the city, and thus saved it from a sack, and the probable loss o' millions of dollars.— W. J. McAlpine, Moving Machinery Hepresented. bj Photographic Projection. All persons who have recently attended the higher classes in o public schools know how much teaching has be3n facilitated by the frequent use of photographic projections with the electric, or Drummond, light. Thanks to this process, says Appleton's Journal, the most delicate objects, whether microscopic or telescopic, can be faithfully represented to an entire audience; and it was supposed, in arriving at these results, that perfection was certainly attained. M. Bourbouze, however, in explaining the gas machine of M. Hugon, experienced many difficulties not before anticipated, while demonstrating the relative movements of the slide and pistons ; and was obliged to repeat, several times, the same design, with the organs in diff'erent positions, with only a partial degree of success. In studying to remedy this defect, we are glad to say he has entirely succeeded, having invented a process that will completely revolutionize the art of projection. He constructs his photographs in movable parts : but turning a small winch, the whole design is correctly demonstrated ; the pistons and slides repeat successively the diff'er-ent relative positions taken by the real machine, and conse quently all difficulties in explaining disappear. This eltnt result has been obtained by the ingenious inventor by means of a very simple arrangement; each movable organ is photographed on a special glass, and these different glasses are arranged in' a frame which contains, on a fixed glass, the photography of the fixed parts of the apparatus represented. The movable glasses are each fixed to a connecting rod moved by a single winch ; the length of each connefting rod being calculated in such a way as to produce accurately the movement required. A RECENT discovery in the Departement de la Dordogne, France, of human skeletons coeval with the mammoths, and undeniably appertaining to the earliest quaternary period, presents features, of such unusual interest that the French government has sent M. Laiter, the palaeontologist, to make a report on the subject. He reports that the bones of five skeletons have been discovered, and that they belong to some gigantic race whose limbs, both in size and form, must have resembled those of the gorilla. But the similar origin of man must not be inferred from these analogies, as the skulls, of which only three are perfect, affbrd testimony fatal to this theory, having evidently contained very voluminous brains. The skulls are now - in the hands of a committee of savants, who are preparing an exhaustive craniological report. some dentists recommend silk floss for cleaning the spaces between teeth, but we know from experience, that No. 8 gum rings are superior. The rings are not only more convenient to handle but they slip through the spaces easier. 72 Improved Portable Iailroad. The invention herewith presented is so simple that at first sight it might strike the mind as puerile. Its practical value is, however, second to few inventions claiming the attention of the public at this time, as has been demonstrated in the large saving efiected by its use. It consists of a series of wooden rails connected together in pairs at suitable distances apart to form sections. These sections are connected to each other by simple fastenings, such as hook catches and eyes, so that they can be readily taken apart or connected as desired. With these wooden rail sections are connected turn-outs, turn-tables, switches, frogs, bridges, and other parts necessary to form a complete railroad. All these parts are made principally of wood, and so light that they can be readily handled by a few men. The sections are twenty feet long with iron straps riveted upon them. The bridges and rafts are composed of ordinary wooden rail sections supported by boards laid crosswise or lengthwise, so that such sections or bridges, when laid on marshy or soft ground, will be prevented from sinking in, and will be capable of sustaining the weight of the cars passing over them. The cars are so constructed that their contents can be readily dumped, and are so low that the operation of loading them is materially facilitated. The track thus constructed readily adapts itself to the formation of the ground on which it is laid, as indicated in the engraving, and the great advantage of the invention will be best understood from a case where it has been applied. In Prospect Park, in Brooklyn, N. Y., large quantities of earth have been moved to fill up sanken places, in excavating lakes, etc. The cost of moving by this method was thirteen cents per cubic yard, against twenty-seven cents by carts, for even a short distance. In Greenpoint, N. Y., 2,500 feet of the portable railroad was laid, and over this road twenty-three trips were made in ten hours by each horse, three horses being employed, each drawing five cars, so that three hundred and forty-five loads of earth were dumped in ten hours, each load being equal to one cubic yard. Twenty men and only three horses were employed, and the saving was over fifty per cent. From this example the great advantage of this portable railroad will be apparent in all operations, such as leveling streets, filling in sunken lots, constructing docks, making excavations, building ordinary railroads, mining, brick manufacture, etc. We take pleasure in calling the attention of the public to this meritorious and labor-saving invention. It will be found of great service in making a road quickly over soft and marshy ground, and so convenient is it to handle that one thousand feet have been laid in a single hour, by a small force of laborers. For military purposes, as well as for the objects already mentioned, it must prove valuable. Over $60,000 worth of rights have been already sold. Patented through the Scientific American Patent Agency, Sept. 4,1866, by A. Peteler, New Brighton, N. Y. For further particulars address A. Peteler & Co., at the same place. Shad Propagation. Intelligence from the Hudson received daily is most encouraging as to the propagation of shad there, under the direction of Seth Green. Mr. Green has lately returned to Rochester and left the work under the direction of his brother, Munroe A. Green who is also very successful. The nets are hauled some two miles from Coeyman's, and the propagating party are fortunate m finding as many of the kind they require as they can well use. They are hatching millions of fishes, which are put into the river. The spawn of these fish would of course be otherwise wasted. The success in this operation has far exceeded the expectations of the Fishing Commissioners and of Mr. Green. M. A. Green is now in chargeof ninety of Seth Green's patent boxes, in which the process of hatching takes place. These boxes are floating in the current, and each of them turn out its thousands of young shad every three or four days. Next year the little shad will be seen quite plentiful in the Hudson, and on the third year they will be fit for the table. Shad fishing in the Connecticut has been excellent this year—the fish that Mr. Green hatched there three years ago having matured.
This article was originally published with the title "Spiders' Silk" in Scientific American 21, 5, 70-72 (July 1869)