and barbarism. The middle class has arisen and becomes an ever-increasing power in the state, as it is fed from below by constant accessions from the most numerous order in society.*

The power of the aristocracy is gone. An Earl of Warwick could once maintain ten thousand retainers, because he retained two-thirds of the produce of his estates in the shape of rent, because men were content to serve for wages that afforded them less of comfort and luxury than fall to the lot of the inmates of the worst hovels in the filthiest quarter of a modern town. The Duke of Wellington maintains perhaps thirty. The men who keep armies now are the chiefs of industry. Thus civil and social equality are worked out gradually, and the posterity of the slave become republican freemen.

Laws which are adequate to explain the past, prophecy the future. The emancipation of the workman comes from Peace, and Concentration. It is postponed by War and Dispersion. The Zoll Verein, the union of thirty millions of people under different governments to maintain free trade with each other, and to increase it by Protection against the system which has formerly driven them to foreign trade, is the greatest among European agencies for the emancipation of labor. It is, as the Westminster Reviewer says, "a question of extending the circle of consumers, of consequently augmenting production, of giving a large share to producers, of opening a wide road to the operative for the acquisition of wealth and property-in short of putting capital and the instruments of labor within reach of every man offering a guaranty of goodwill, capacity, and morality. This question is being solved, and these objects are being attained, everywhere, just in proportion as men protect themselves from being made tributary to sustaining Great Britain in a monopoly of manufacturing, which she can only retain, by keeping wages down. Her system inculcates, to producers everywhere, that their interest should be, what Silas Wright declared our agriculture has ever been and must remain, an exporting interest. Every exporting interest is based upon keeping wages down, and all who accept such counsels, join in a conspiracy against the elevation of labor at home and

abroad.

E. P. S.

Art. VI. THE NAVAL DRY DOCKS OF THE UNITED STATES.+

THE Naval Dry Docks of the United States constitute some of the most stupendous mechanical enterprises of the country, and in one or two instances they are surpassed in extent and the difficulties of their construction by few similar works in the world. The number of these docks is seven. They are located at the navy yards of New York, Philadelphia, Boston, Portsmouth, Norfolk, Pensacola, and San Francisco. Their cost has been not less than seven millions of dollars.

Statutes regulating the wages of labor, and compelling men to labor at fixed rates, were successively enacted in England till a very recent period, the rates continually rising. Corporation privileges have been restricted-the laws preventing combinations of workmen, the emigration of artisans, &c., have been repealed, &c., &c.

The Naval Dry Docks of the United States. By Charles B. Stuart, Engineer-in-Chief of the United States Navy. Illustrated with twenty-four fine engravings on steel. Quarto, pp. 218. New York: Charles B. Norton.

By far the most extensive, costly, and magnificent of these structures is the Granite Dry Dock of New York. It is the largest in the world, and in the admirable plan and principles upon which it is built, it will remain for ages one of the proudest monuments of the engineering and mechanical skill of the nineteenth century.

We propose to give a brief history, and an outline of the plan of this vast structure, sufficient to convey to our readers some adequate idea of the extent and importance of this general subject; and our remarks will be confined chiefly to points embraced in the recent valuable work of Mr. CHARLES B. STUART, Engineer-in-Chief of the navy. This is the first work of any extent and magnitude upon the subject which has been offered to the American public. It aims to show in the most practical manner the mode of working these docks, and to give a complete history and description, in the fullest detail, of the Granite Dock at New York, the Floating Sectional Dry Dock at Philadelphia, and the Floating Balance Dry Dock, Portsmouth. It is illustrated with numerous, large, finely executed, and accurate steel engravings; and it is such a work as was wanted to give to the world the information, in regard to this branch of the public service, which has heretofore been chiefly confined to the officers of the government. The details which it contains relating to the different materials of which these works are made, the entire cost of construction, &c., are adapted to instruct statesman and the man of science. The entire appearance of the volume, its typography, engravings, paper, &c., are very fine.

The site for a naval dry dock in the harbor of New York was examined as long ago as 1826. Nothing, further, however, was done about it until 1835, when Congress authorized an examination for a definite location. But no decisive measures were taken until March, 1841, when Congress appropriated fifty thousand dollars for commencing the work. The work was afterwards suspended, a new examination of the location made, and an investigation into the merits of the various kinds of dry docks. It was not until October, 1844, that it was again resumed, under the charge of Gen. W. G. MCNEIL. By him the plans for the masonry were enlarged and matured, the coffer dam was extended, and the excavation removed to the level of low-tide.

From April, 1845, to June, 1846, the superintendence was committed to W. P. S. Songer, who continued the construction of the coffer-dam and the dredging of the excavation below the water inside the dam.

From June, 1846, to October, 1849, the labor was under the superintendence of W. J. McAlpine. It consisted of enlarging and completing the cofferdam, the excavating of the bottom portion of the pit excavation, the driving of the foundation piles, the putting in the foundation timbers and concrete, the construction of a large portion of the superstructure of the dock, and the foundations of the pump, well, and engine-house.

In October, 1849, Gen. Stuart assumed the charge of the work and continued until the date of its completion, in August, 1851. Under the direction of Gen. Stuart, the superstructure was completed, and the construction of the iron-turning gates, the various culvert gates, the pumping-engine, and pumps, the floating-gate or caisson, the iron work of the engine house, the completion of the dock apron, and the removal of the coffer-dam performed. The superstratum of the site selected for the dock, in the Wallabout Bay, was found to be chiefly formed by vegetable decomposition, to the depth of ten feet; below this there is an almost impalpable quicksand,

containing a large proportion of mica. When confined and not mixed with water, it is very firm and unyielding, and presents a strong resistance to penetration, but when saturated with water, it becomes semi-fluid and is moved by the slightest current of water passing over or through it. As it was necessary to place the foundation thirty-seven feet below mean level, a coffer-dam was required. One was, therefore, constructed four hundred and seventy feet long, and from sixty to one hundred feet wide. The total cost of this dam, including repairs of breaches, was nearly two hundred and forty-six thousand dollars.

The pit, which was excavated for the foundation, covered an area of two acres at the top and one acre at the bottom. It was sunk to the depth of forty-two feet in the earth. When the excavation had extended to within about six feet of the required level, springs of fresh water burst up and were the cause of the greatest difficulty in laying the foundations. The stratum through which it flowed was evidently at a great depth, and even when contiguous they were not united. A very interesting account of the difficulties which were occasioned by these springs is given by Mr. Stuart in his work, from which we make a brief extract:

"The difficulties did not proceed from the mere flowing of the waters, but this, as it came up, brought with it large quantities of sand, so fine and impalpable as to insinuate itself through the smallest interstices, even through the checks and cracks of the timbers, and if allowed to flow in this way would soon have endangered the surrounding works; nor could the water be checked with safety, as its pressure was found sufficient to raise the foundation, however heavily it could be loaded. It became necessary, therefore, to provide for the flow of the water, and at the same time check the escape of the sand.

"One of the most powerful springs was encountered near the temporary pump-well, at the north-east corner of the dock. The first evidence of undermining from this spring was the settling of the piles driven to support the pumps and engine, rendering it necessary to change the pump-well; but the spring followed, and compelled another change of the well. This spring was driven out of the old well by filling it with piles, but immediately burst up among the foundation piles of the dock near by. In a single day it made a cavity in which a pole was run down to the depth of twenty feet below the foundation timbers. One hundred and fifty cubic feet of cobble-stone were thrown into this hole, which settled ten feet during the night, and fifty cubic feet were thrown in the next day, which drove the spring to another place where it undermined and burst up through a bed of concrete two feet thick. This new cavity was repeatedly filled up with concrete, leaving a tube for the water to flow through; but in a few days it burst up through a heavy body of concrete, in a place fourteen feet distant, where it soon undermined the concrete, and even the foundation piles, so that they settled from one to three inches. These piles were thirty-three feet long, and driven by a hammer weighing two thousand pounds, pulling thirty-five feet at the last blow, with an average of seventy-six blows to each pile, the last of which did not move the pile over half an inch.

"This alarming result rendered paramount the adoption of the most thorough measures, to prevent any further injuries from this source. It was accordingly determined to drive as many additional piles as could be forced into the space, and by means of followers, to force those already driven as deep as possible. This was done although under many disadvantageous circumstances, the old concrete was removed to a depth of twenty inches below the top of the piles; an area of about one thousand square feet around the spring was then planked, on which a floor of brick was laid in dry cement, and on that, another layer of brick was set in mortar made of Roman cement; the space was next filled with concrete and the foundations completed over all, in the usual manner and with the greatest dispatch possible; several vent holes were left through the floor and

foundations. After a few days' interval, when the cement had become set, the spring was forced up to a level of about ten feet above the former outlet, and at this point it flowed clear, and no longer charged with sand.”

There were about forty of these springs, which were treated in the same successful manner.

The piles are chiefly sound spruce timber from twenty-five to forty feet long, and averaging fourteen inches diameter at the head. The number of bearing piles is six thousand five hundred. They were mostly driven to the point of absolute resistance. The number of blows given to each and the depth driven by every blow were recorded.

But we must pass over the details of making the foundation and of the apron to protect the front of the dock from undermining, to notice the splendid masonry of this magnificent structure. The work of Mr. Stuart will be found to contain even the minutest detail of importance.

There is perhaps no modern structure that compares with this national work in the dimensions or the durability of the materials of which it is composed, or the beauty and accuracy of their workmanship. Eighty thousand tons of stone have been used in its construction. The masonry foundations are four hundred feet in length, and one hundred and twenty feet in breadth. The main chamber is two hundred and eighty-six feet long, and thirty feet broad on the bottom; three hundred and seven feet long and ninety-eight feet broad at the top, within the folding gates. By using the floating-gate an additional length of fifty feet may be obtained. The hight of the wall is thirty-six feet. The smallest face stone exceeds three thousand pounds in weight, and the average is about six thousand pounds. The facing stones are all laid to a joint not exceeding three-sixteenths of an inch, and the joints are kept up full to the line, for the full depth of the stone. The quantity of cement used was twenty-nine thousand one hundred and forty-seven barrels.

But our limits will not permit us to follow this interesting description through the details of the construction of the "pump-well and culverts;" "the engine house;" "the turning-gates;" "the floating-gate;" "the culvert-gates;" "the iron-capstans;" "the pumping-engine and pumps ;" "removal of coffer-dam;" &c., &c.

܂

The work was just ten years in process of construction. The aggregate expenditure exceeds two million one hundred and fifty thousand dollars. Four hours and twenty minutes is the time required for the complete docking of the largest ship.

In this work, by Mr. Stuart, we are next presented with an ample account of the dry docks at Boston and at Norfolk. This is followed by a description of large and very beautiful plates in illustration of the subject, and by an appendix which concludes the first part.

The contents of the second part are the details of the dock at Philadelphia; the history and description of the California Dock, and the details of the one at Portsmouth. It would be exceedingly interesting to enter more fully into this subject, and to contrast the features of the Granite, the Floating-Sectional, and the Floating-Balance Docks; but it would lead us too far and consume too much of our limits.

We cannot leave the subject without bestowing our thanks upon the accomplished author of this work, for the splendid volume which he has produced upon a subject of such vital importance to commercial and naval affairs, and for the tasteful and elegant manner in which it has been produced by that

young and enterprising publisher, CHARLES B. NORTON, of New York. We trust the public will appreciate these labors and bestow upon them that high degree of patronage to which they are so justly entitled.

Art. VII-QUESTIONS RELATING TO THE THEORY OF STORMS.

FREEMAN HUNT, Esq., Editor Merchants' Magazine :—

DEAR SIR:-In the number of your magazine for February last, you republished some strictures on the report on storms, made by Prof. Espy, to the Naval Department of the United States. Since then, I have received officially, a quarto pamphlet entitled "ESPY'S REPORT ON METEOROLOGY."

In this addition there are a number of important generalizations. These have suggested a series of queries to Prof. Espy, as well as to meteorologists in general, which it may be expedient for you to insert in your periodical.

Every farmer, navigator, and merchant, must take an interest in whatever concerns the weather. I hope, therefore, that my queries may be sufficiently popular for insertion in a magazine, intended for a body of men so intelligent and well educated, as American merchants are in general. Truly yours,

ROBT. HARE.

QUERIES BY DR. HARE, TO PROF. ESPY, OR TO METEOROLOGISTS IN GENERAL, INDUCED MAINLY BY CERTAIN GENERALIZAIONS IN ESPY'S REPORT TO THE

NAVAL DEPARTMENT.

Having been called on officially to give his opinion on Prof. Espy's labors, Dr. Hare has preferred to publish them in full, rather than resort to a brief epistolary juridical communication.

The subjoined generalizations are quoted from the quarto pamphlet, entitled "Espy's Reports on Meteorology," page 5.

1. "The rain and snow storms, and even the moderate rains and snows, travel from the west towards the east in the United States, during the months of November, December, January, February, and March, which are the only months to which these generalizations apply."

2. "The storms are accompanied with a depression of the barometer near the central line of the storm."

3. "This central line of minimum pressure is generally of great length from north to south, and moves side foremost towards the east."

5. "The velocity of this line is such, that it travels from the Mississippi to the Connecticut river in about twenty-four hours, and from the Connecticut to St. John's, Newfoundland, in nearly the same time, or about thirty-six miles an hour."

7. "In great storms, the wind, for several hundred miles on both sides of the minimum pressure, blows towards that line directly, or obliquely."

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10. Many storms are of great and unknown length, from north to south, reaching beyond our observers on the Gulf of Mexico and on the northern lakes, while their east and west diameter is comparatively small. The storms, therefore, move side foremost."

11. "Most storms commence in the far west,' beyond our most western observers; but some commence in the United States."

13. "There is generally a lull of wind at the line of minimum pressure, and sometimes a calm."