am fully persuaded that the whole of our ships of war must be rebuilt of iron, and defended with iron armor calculated to resist projectiles of the heaviest description at high velocities.

"In the early stages of iron ship-building, I believe I was the first to show, by a long series of experiments, the superiority of wrought iron over every other description of material in security and strength, when judiciously applied in the construction of ships of every class. Other considerations, however, affect the question of vessels of war; and although numerous experiments were made, yet none of the targets were on a scale sufficient to resist more than a six-pounder shot. It was reserved for our scientific neighbors, the French, to introduce thick iron plates as a defensive armor for ships. The success which has attended the adoption of this new system of defence affords the prospect of invulnerable ships of war; and hence the desire of the government to remodel the navy on an entirely new principle of construction, in order that we may retain its superiority as the great bulwark of the nation.

"It is asserted, probably with truth, that whatever thickness of plates are adopted for casing ships, guns will be constructed capable of destroying them. But their destruction will even then be a work of time; and I believe, from what I have seen in recent experiments, that, with proper armor, it will require not only the most powerful ordnance, but also a great concentration of fire, before fracture will ensue. If this be the case, a well-constructed iron ship, covered with sound plates, of the proper thickness, firmly attached to its sides, will, for a considerable time, resist the heaviest guns which can be brought to bear against it, and be practically shot-proof. But our present means are inadequate for the production of large masses of iron; and we may trust that, with new tools and machinery, and the skill, energy, and perseverence of our manufacturers, every difficulty will be overcome, and armor-plates produced which will resist the heaviest existing ordnance.

"The rifling of heavy ordnance, the introduction of wrought iron, and the new principle of construction with strained hoops, have given to all countries the means of increasing enormously the destructive power of their ordnance. One of the results of this introduction of wrought iron and correct principles of manufacture is the reduction of the weight of the new guns to about two-thirds the weight of the older cast-iron ordnance. Hence follows the facility with which guns of much greater power can be worked, whilst the range and precision of fire are at the same time increased.

"Iron Bridges. — We have seen a new era in the history of the

construction of bridges, resulting from the use of iron; and we have only to examine those of the tubular form over the Conway and Menai Straits to be convinced of the durability, strength, and lightness of tubular constructions applied to the support of railways or common roads, in spans which, ten years ago, were considered beyond the reach of human skill. When it is considered that stone bridges do not exceed one hundred and fifty feet in span, nor cast-iron bridges two hundred and fifty feet, we can estimate the progress which has been made in crossing rivers four or five hundred feet in width, without any support at the middle of the stream. Even spans greatly in excess of this may be bridged over with safety, provided we do not exceed eighteen hundred to two thousand feet, when the structure would be destroyed by its own weight. "Importance of Good Machinery. It is to the exactitude and accuracy of our machine-tools that our machinery of the present time owes its smoothness of motion and certainty of action. When I first entered Manchester, the whole of the machinery was executed by hand. There were neither planing, slotting, nor shaping machines; and, with the exception of very imperfect lathes, and a few drills, the preparatory operations of construction were effected entirely by the hands of the workmen. Now everything is done by machine-tools, with a degree of accuracy which the unaided hand could never accomplish. The automaton, or self-acting machine-tool, has within itself an almost creative power; in fact, so great are its powers of adaptation that there is no operation of the human hand that it does not imitate. "Telegraphy. — A brief allusion must be made to that marvellous discovery which has given to the present generation the power to turn the spark of heaven to the uses of speech; to transmit along the slender wire, for a thousand miles, a current of electricity that renders intelligible words and thoughts.

"In land telegraphy the chief difficulties have been surmounted, but in submarine telegraphy much remains to be accomplished. Failures have been repeated so often as to call for a commission on the part of the British Government to inquire into the causes, and the best means of overcoming the difficulties which present themselves. I had the honor to serve on that commission, and I believe that from the report, and mass of evidence and experimental research accumulated, the public will derive very important information. It is well known that three conditions are essential to success in the construction of ocean telegraphs, -perfect insulation, external protection, and appropriate apparatus for laying the cable safely on its ocean bed. That we are far from having succeeded in fulfilling these conditions is evident from the fact

that out of twelve thousand miles of submarine cable which have been laid since 1851, only three thousand miles are actually in working or der; so that three-fourths may be considered a failure and loss to the country. The insulators hitherto employed are subject to deterioration from mechanical violence, from chemical decomposition or decay, and from the absorption of water. But the last circumstance does not appear to influence seriously the durability of cables. Electrically, India-rubber possesses high advantages, and, next to it, Wray's compound and pure gutta-percha far surpass the commercial gutta-percha hitherto employed; but it remains to be seen whether the mechanical and commercial difficulties in the employment of these new materials can be successfully overcome. The external protecting covering is still a subject of anxious consideration. The objections to iron wire are its weight and liability to corrosion. Hemp has been substituted, but at present with no satisfactory result. All these difficulties, together with those connected with the coiling and paying out of the cable, will no doubt yield to careful experiment, and the employment of proper instruments in its construction, and its final deposit on the bed of the ocean.

“Irrespective of inland and international telegraphy, a new system of communication has been introduced by Prof. Wheatstone, whereby intercourse can be carried on between private families, public offices, and the works of merchants and manufacturers. This application of electric currents cannot be too highly appreciated, from its great efficiency and comparatively small expense. To show to what an extent this improvement has been carried, I may state that one thousand wires, in a perfect state of insulation, may be formed into a rope not exceeding half an inch in diameter."

The Congress for the Promotion of Social Science, which has now become an established institution in Great Britain, met, during the past year, at Dublin, and was largely attended,—some ninety-three papers being read and discussed. Of these communications we note the following, by title, as affording our American readers an idea of the scope and objects of the Congress :—

Suggestions on the Failure of Education in the Junior Classes of Elementary Schools; by the Rev. W. A. Willock, D.D.” "On the Application of the Principles of Education in Schools for the Lower Classes of Society; by Miss Carpenter." "A Scheme for the Adult Education of the Working Classes; by Mr. J. P. Organ." "Paperhangings Auxiliaries to Education; by Mr. J. Stewart." "On the Influence of Newspapers on Popular Education; by Mr. G. W. Blanchard Jerrold." "On Art Education considered in its Utilitarian and

Social Aspect; by Mr. M. A. Hayes." "On the more Prominent Causes of an Excessive Mortality in Early Life; by Dr. Moore." "On the Physical Degeneration of Town Populations; by Dr. Beddoe." "On Hospital Statistics; by Florence Nightingale." "On the Influence of the Food on the Intellect; by Dr. H. Kennedy." "On the Health of Merchant Seamen; by Dr. J. O. William." "On Practical Sanitary Work in Town and Country; by Mrs. Fison." "On Quarantine; by Dr. Milroy." "On the Application of Sanitary Science to Public Works of Irrigation; by Mr. E. Chadwick." "On the Disposal of Boys from Reformatories; by the Rev. J. Fish." "On Sentences, with a view to Reformation or Deterrence; by T. B. L. Baker." "On Punishment, its Effects by way of Example; by Mr. C. H. Footc." "On the Condition of the Working Women in England and France; by Miss Parkes." "Women Compositors; by Miss Emily Faithfull." "On the Law of Fluctuation in Wages; by Prof. H. Hennessy." "On Working Men's Reading-rooms; by Dr. R. Elliott." "On the Condition of the Working Classes and their Dwellings; by the Rev. J. B. Robinson." "On the Superior Economy of Administration of Voluntary as distinguished from Legal Charity; by Major O'Reilly." "On the Necessity of a Universal System of Weights, Measures, and Coinage; by M. Chevalier, of France.” " On Public Prosecutors in Prussia; by Baron Holtzendorff.” "Should the Accounts of Joint Stock Companies be Audited by a Public Officer? by Mr. D. C. Heron." "Observations on the Proposal of Admitting the Evidence of Accused Persons on their Trial; by Mr. P. J. McKenna.”

The Emperor of Russia has recently placed in the hands of M. Struvé, the distinguished Russian astronomer, the sum of 125,000 francs, to enable him to erect an observatory on the summit of Mount Ararat, in Persia. It is hoped that, under the remarkably clear skies of this country, important astronomical results will be attained to.

A scientific expedition has been set on foot by the Government of India, for the exploration of the great mountain chains of Central Asia. It will consist of five men of science,-geologists and physicists, who, early in 1862, will traverse the Himalaya and Karchan chains, and, proceeding into Tartary, explore the great Thian-Chan; then, passing eastwards, return to Hindustan by the gorges of the Brahmaputra River.

An English commission is now engaged, in coöperation with a commission appointed by the French Government, for the purpose of connecting the triangulation of Great Britain with that of France and Belgium. The ultimate result to be obtained is the substitution of one meridional line for the lines of Greenwich, Paris, and St. Petersburg,

that are at present in use in different countries, and thus to harmonize the maps of all countries. The connection of the French and Russian systems will be carried out by the officers of those countries.

Uriah A. Boyden, Esq., of Boston, Mass., has deposited with the Franklin Institute, of Philadelphia, the sum of one thousand dollars, to be awarded as a premium to "any resident of North America who shall determine by experiment whether all rays of light, and other physical rays, are or are not transmitted with the same velocity." The award is to be made by a committee of three citizens of the United States, of competent scientific ability, to be appointed by the managers of the Institute.

Prof. Torrey, of New York, the well-known botanist, has presented to Columbia College his immense herbarium, the fruit of forty years' assiduous labor,—together with his valuable botanical library. The herbarium is especially rich in North American plants, as it contains full sets of nearly all the collections made by the numerous exploring expeditions of the United States Government, from that of Maj. Long, in 1819, to the present time, and the original specimens from which the descriptions in the official reports were made. The herbarium is also authority for the plants described in the Flora of North America, by Dr. Torrey and Dr. Gray. The Floras of Europe, Asia, the Cape of Good Hope, Australia, and many other parts of the world, are largely represented by collections named by the highest authority. Patents. Within the past year some important changes have been made by Congress in the United States system of Patent Laws, of which the following are the most noticeable:

Under the new system, pictures, prints, and artistic designs of every description, may be patented, and no person can use or duplicate the same without the consent of the originator. Merchants may obtain patents upon their trade marks, and even upon the labels which they affix to their goods. This provision also covers, in particular, ornamental designs in any fabric or material; every new style of tool or pattern used or produced in any trade; and ornaments and decorations formed from any material. In short, any new form of any article of manufacture may be patented. Makers of such articles will therefore be encouraged to exercise ingenuity in producing improved forms, so as to enjoy a monopoly of the sale thereof.

Patents can be taken out under the new system, in accordance with the above provisions, for three and one-half, seven, or fourteen years, as the applicant desires; and the following is the tariff of fees established by Congress for the same:—

For a patent of three and one-half years, ten dollars; for a patent