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the internal compressed portion to attain its normal condition before this internal portion (which is the first to break in the common gun) is subject to any strain at all. It will be perceived that if this principle could be rigorously applied, a cannon could be made so perfect that, when subjected to a bursting pressure, every fibre, from the internal to the external surface would be at that instant equally extended, each contributing its full share of resistance to fracture. The whole resistance would be proportional to the area of fracture.

This was supposed to be the case in common cylinders, before the error was pointed out by Barlow, and also by Lamie and Clapeyron. And it was this erroneous supposition that led Count Rumford to his exaggerated estimate of the force of gunpowder, as tested by its power of bursting gun-barrels. If he had used the theory which gave origin to the hooped gun, his results would nearly have agreed with modern observations.

The demonstration of the superiority of the hooped gun, with detailed directions for its construction, is contained in a paper read before this Academy in February, 1856, and published at the beginning of the sixth volume of our Memoirs. This was the first published account of the invention, which had been patented nearly a year before. Captain Blakely's pamphlet, published in England in 1858, sets forth the advantages of this construction by similar arguments; as also does an elaborate paper read by Mr. Longridge before the Institution of Civil Engineers in February, 1860. Both these gentlemen, however, were engaged in researches upon this subject at an earlier date, but not so early, it would appear, as was Mr. Treadwell.

The validity of the principle, and the soundness of Mr. Treadwell's views upon the whole subject, as set forth in his memoir, have been amply confirmed by special experiments made in England with the Blakely and Whitworth guns, and by experience in this country during the last four years with the Parrott and the Blakely guns.

It must not be supposed that the earlier invention is superseded by the later one. That is used in forming the hoops of the Parrott gun, and in most of the British guns. And the best gun which could now be made, as experience has shown, would be composed of a barrel of cast-iron or steel, enclosed and compressed by a cylinder of coil.

We need not discuss the question of priority of invention between Mr. Treadwell and others, competitors for a share in the honor of producing the modern cannon. His independence of each and all of them

VOL. VII.

has never been called in question. Nor will it ever seriously be thought that the previous futile attempts at constructing wrought-iron and banded guns, — foredoomed failures both in theory and practice, and destitute of all pretension to a knowledge of the guiding principles now clearly seen to be essential to success, — should detract in the slightest degree from the great honor which our associate has, by a clear insight into the conditions of the problem and the resources of physical science, so fairly and completely won.

Upon these two inventions has been set the seal of experience. But there is still another memoir, read by Professor Treadwell before this Academy in April, 1864, and printed soon afterwards, which promises to add a third important improvement in the construction of artillery.

Perceiving that the body of a hooped gun, if made of unmalleable cast-iron, compressed by a soft wrought-iron hoop, must give way, by the fracture of the cast-iron, before the hoop can approach the ultimate limit of its strength, and that this was, in fact, a principal cause of the failure of so great a part of the large guns of Blakely and Parrott, Professor Treadwell, as the principal result of this third investigation, proceeds to show, that, to attain with effect the end sought for by hooping a cast-iron gun, it is necessary to harden the wrought-iron hoop by cold bammering and severe stretching before placing it upon the gunbody. He computes, that, by this simple means, a hooped gun may be made more than twice as strong as those which have been constructed by Blakely and Parrott, the materials being in both cases the same.

In this important discovery, as also in other matters discussed in his latest memoir, we are gratified to see, that, although now carrying the weight of more than threescore and ten years, our veteran colleague still keeps the lead, which he gained at the start, of his competitors in this race of improvement.

So completely do these three improvements cover the ground, that if the works of all other inventors who claim a share in the great gun of the nineteenth century were lost, the gun could be restored (rifling excepted) from Mr. Treadwell's papers alone.

And now, Mr. Treadwell, in delivering into your hands this beautiful gold medal and its silver duplicate, I have much pleasure in conveying with them the congratulations and best wishes of your associates here assembled ; also the expression of their hope that you may yet longer lead the race; and especially that you may long enjoy the scientific honors which you have worthily won; and with them, if it may be so, the full recognition of the rights, and possession of the advantages, which pertain to your inventions.

On receiving the medal, Mr. Treadwell expressed his acknowledgments as follows:

Mr. President and Gentlemen of the Academy :

I receive with great satisfaction the Rumford Medal which, in accordance with a vote passed at the Annual Meeting, you have now presented to me. I prize this premium the more as coming from this body, with which I have been intimately associated for more than forty years as an active member, and for a very large part of the time as an officebearer. I may be permitted to say, however, that, although I am sensible that I am indebted for this award in a large degree to your kind partiality for an old associate, which turned your attention to his labors, yet it was made not only without any application on my part, but your motion towards it was wholly unknown, and not even thought of by mé, until the vote of the Rumford Committee was communicated to me.

The award was, as stated in your vote, (which uses the language of Count Rumford,) for “improvements in the management of heat.” But as this management of heat was incidental to, and intimately connected with, improvements in the construction of cannon, to which I had given years of labor, you have extended your examination into the character of those improvements generally. For the very thorough research which it is evident you have made into the whole subject, I feel under great obligations to you; and the very favorable conclusions which you have reached, and which have been so fully and kindly expressed by you, Sir, as to the originality and value of my researches and labors, form an additional source of satisfaction to me. This, taken alone, would constitute one of the most welcome recognitions and rewards that could be given to me. Permit me, in conclusion, to express my special obligations to the members of the Rumford Committee for directing their attention to my labors, and for the very favorable view which they have taken of their merits.

The President then introduced Dr. Burt G. Wilder, who presented the following communication :

On the Nephila Plumipes, or Silk Spider. By Burt G. WIL

DER, S. B., late Surgeon 55th Mass. Vols.

At the north end of Folly Island, which lies just south from the harbor of Charleston, S. C., on the 20th of August, 1863, I found in a tree a large and very handsome geometrical spider, whose web was about three feet in diameter. While examining the insect at my tent, it occurred to me to see how much of the silken thread could be drawn from the spinners. As it was not disturbed by pulling out a few yards, I wound the thread around a quill, and then, by turning this in my fingers, reeled off silk from the body of the spider for one hour and a quarter, at the rate of six feet per minute, making one hundred and fifty yards of most beautifully shining golden silk. This specimen is still in my possession, and, having been removed from the quill, weighs one third of a grain. I had never before seen this spider, nor had I ever heard of this method of obtaining a silken material; but when, during the following summer, another officer of our regiment * described to me a large spider as very common upon Long Island, which lies just west from Folly Island, I knew it was the same, and told him what I had done, adding that I was sure something would come of it in time. By substituting a cylinder worked by a handle for mine turned in the fingers, this officer obtained more of the silk, winding it upon rings of hard rubber, and afterward, by using a "gear-drill stock,” another officert accomplished similar results still more rapidly.

With this "gear-drill stock” I wound from a number of spiders three thousand four hundred and eighty yards of silk upon the periphery and over the sides of a hard rubber ring; the length being accurately measured by multiplying the dimensions of the ring where wound upon by the number of revolutions per minute, and this product by the number of minutes of actual winding. This was in the fall of 1864, and in February, 1865, I showed specimens of the spider and of the silk to Professors Wyman, Agassiz, and Cooke of Harvard University, neither of whom had ever heard of this way of obtaining silk, nor, with the exception of Professor Wyman, — who found a single individual among some specimens collected at the South, — had they ever seen the insect. At this time, too, a friend to whom the whole history of the matter was known, expressed his confident belief that this new silken product could be made of some practical utility, especially in view of the anticipated scarcity of ordinary silk; and it is in great measure due to his advice and assistance that the experiments and investigations recounted below have been made.

* Major Sigourney Wales, 55th Massachusetts Volunteer Infantry. | Lieut.-Col. Charles B. Fox, 55th Massachusetts Volunteer Infantry. | Dr. William Nichols of Boston.

The only mention of this spider is in the German work of C. L. Koch, “Die Arachniden,” where in Vol. VI. is described, under the . name of Nephila plumipes, a mutilated female specimen, the only one ever collected, and which is preserved in the museum of J. Sturm at Nuremberg. This description and its accompanying figure are very imperfect, but until a careful comparison can be made between the original specimen and some of my own, I will consider the latter as · representatives of N. plumipes; though an accurate description and figure shall be made as soon as possible.

The following general description applies only to the females, the males being very small and of a different color.

NEPHILA (PLUMIPES ?) Koch. A large and very elegant species of Nephila, resembling most of its congeners in the general form of the body, and, like N. clavipes and N. fasciculata, possessing peculiar collections of stiff hairs upon the legs, but differing from these two species in that these bairs are more closely set so as to justify the German term “Haarbürste” (Hair-brushes).

In general the cepalo-thorax is black above, but covered, except in spots, by silver-colored hairs. The abdomen is olive-brown, variously marked with yellow and white spots and stripes. On the first, second, and fourth pair of legs are one or two brushes of stiff black hairs pointing outward away from the body. The length of the body is one and one tenth inches, and the spread of the legs from two and three fourths in a lateral, to three and three fourths inches in a longitudinal direction. The length of the body of the male is about one third of an inch, and his general color is brown. His palpi are clubbed near the extremities, and end in a sharp point turning outward.

With the exception of the first and only specimen discovered upon Folly Island, and a cocoon found on James Island, I have met with this spider only upon Long Island and one or two similar bits of land in the vicinity. They are all low, sandy, and marshy, covered with palmetto and pine trees, uninhabited, and apparently never before visited by naturalists.

These spiders are specially abundant upon Long Island, and are

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