be the object of every expedition, military or naval, preliminary to any attempt on the southern trade or territory.

At present the force of large vessels for the southeast coast would be obliged to use the harbor of Brunswick as their depot, refuge, and centre of operations. The report of the commissioners has already decided this to be the best south of the Chesapeake. With the command afloat, Key West and the Tortugas might be used, but not otherwise, as no supplies are to be had at either, and no water at the latter. Pensacola would have to answer for the Gulf shore.

The coast of the Pacific States differs in many respects from that of the Atlantic in formation as well as in condition.

The circumstances of settlement, product, and trade have yet to determine much that will govern in the extent and application of the elements of defence. At present there can be no doubt that the two great harbors at San Francisco and the Columbia river will require immediate measures for their protection. The sites of land works have probably been vindicated by the engineers sent for that purpose, though some time must elapse before these can be completed. It seems, therefore, that the naval force in these regions should be of the most effective character in power and number, singly and collectively, inasmuch as it must for a while be the exclusive reliance for a defence of any kind of harbors, as well as of coasts. The squadron should always be able to land at any point a force of two thousand seamen and five hundred marines, which, with twenty or thirty of the boat howitzers on their field carriages, would be found an effective auxiliary in emergencies.

The manner in which our own squadron operated along the coast of California while held by the Mexicans will best exhibit the character of the attempts likely to be made by an enemy against our own people now inhabiting that State. If the views above expressed, in relation to the defence of the United States harbors and coasts, be correct, it then remains to consider the species of naval force which will be required to perform the part assigned to it.

By referring to the navy list it will be seen that the number of heavy ships that is available, or could be made so by necessary repairs, consists of nine lineof-battle ships, twelve frigates, and five steamers.

This force is obviously too smal' for the objects for which a navy should be designed. If the number already assumed to be required for the defence of the Atlantic coast in war be applied to that purpose, it would leave a very insufficient force for the Pacific shores, for the protection of the line of communication by sea between the Atlantic and Pacific States, and for general cruising to cover our own commerce, and annoy that of the enemy.

Not only is the effective number of the present navy too small, but the character of the force has been depreciated to a very serious extent by the superior powers of offence that have been conferred on the large steamers that now constitute part of a navy here and elsewhere. The cannon carried usually as the main reliance of line-of-battle ships and frigates are thirty-two and forty-twopounders. In our service the latter calibre may be consi tered as exceptionable, inasmuch as it is not recognized by the regulations of 1845.

The war steamers carry sixty-four pounders. It is true that the line-of-battle ships may have one hundred of the thirty-two-pounders, while a steamer of the same tonnage has but three of the sixty-four-pounders.

But it will be admitted that if the constituent of one battery is deficient in any one element of power, which is possessed by that of another battery, that no mere increase in the number will compensate for this defect. Thus, if the thirty-two-pounder shot fired with nine pounds of powder be inferior to a shot of sixty-four pounds fired with sixteen pounds of powder in the distance to which it will range with sufficient force to do material damage, then it is plain that so long as that distance can be preserved it will matter little whether a H. Rep. Com. 86-32

ship oppose one hundred or one thousand thirty-two-pounders to the three sixtyfour-pounders: she will receive constant damage from the repeated efforts of the small number of large pieces without the power of inflicting any harm by her large number of small pieces. A similar relation, in effect, may be noted in the effects of other military projectiles. Thus, we know that grape from a thirtytwo-pounder would be harmless against the side of a ship, when the shot would pass through easily, and yet the stand of grape is composed of three-pound shot which, even if fired separately, would still be very little nearer the effect of the thirty-two-pounder shot.

The important question is in relation to the capacity of the steamer to maintain the distance suited to her powers of annoyance-and of this there can be little doubt since the passage between the United States and England is made with ease and certainty in the severest winter weather by the steam packets, their average speed being then seven to eight knots with fair and foul winds, and they could in all probability go very little below their highest rate in any weather in which cannon could be used.

Those who have witnessed the performance of the Mississippi in some of the Mexican "northers" know what can be done by a good steamer in a strong gale. Thus the twenty steam frigates would be very unequally matched in action, by our covering squadron of sailing ships with the thirty-two and forty-two-pounders, if it could be said that they were matched at all. The remedy for this is not difficult, and can readily be attained by a reorganization of our armament, though it would be more expensive to adapt the present sailing ships fully to the ordnance which experimental practice has indicated as preferable than to build new ships. Thus a two-decker would carry the same weight of metal, but not the same number of cannon. Hence, it would become necessary to reduce the number of ports, and to re-distribute them along the broadside; and to do this, the whole planking and frame, nearly to the water's edge, must be removed and replaced to suit the changes required in piercing the side with the proper number of ports-involving an expense equal to half the cost of a new ship.

They would still need an addition that could not be dispensed with, which is an auxiliary steam power sufficient to give a moderate rate in a calm, in manoeuvring or in getting out and in harbor. For this purpose, greater length would be required than any of our present frigates possess, as they now barely stow the provisions and water required for distant cruising. If these ships be cut and lengthened, the cost in connexion with that necessary for heavier ordnance will be fully equal to the expense of building new ships with every disadvantage that can attach to a sacrifice of unity of design in model; for no skill in the builder could possibly develop any one essential of form in this piece of patchwork, except by mere accident.

The true policy, not only as regards economy, but in reference also to accomplishing the object in view, is to commence without delay the reorganization of our naval power by the gradual addition of ships built upon the most recent models, and to carry heavy ordnance as well as an auxiliary steam power.

The experimental practice at the navy yard has developed some points of interest in relation to the pieces likely to combine the several essentials of accuracy, range, and force, and the bearing of all the results has induced me to propose the construction of a class of ships designed to unite a higher degree of efficiency than any frigate or seventy-four mounting the present armament, &c. Instead of twenty-six thirty-two-pounders, and four eight-inch shell guns on the gun deck, the new frigate is to carry twenty-six nine-inch shell guns. The comparative penetrating power of the two pieces is shown in the sketch annexed: The thirty-two-pounder shot passed twenty-one inches into an oak target, three-fourths of a mile distant. The nine-inch shell, uncharged, broke through the whole thickness of thirty inches.

Shot from a long 32-pounder, charge 9 lbs.-Penetration in oak, distant 1,300 yards, thickness 30 in.

The diminution of force which both would undergo at greater distances would lessen the power of the thirty-two-pounder shot yet more, while the nine-inch shell would still retain every advantage arising from its explosive power. The only pieces of the present force that would approach it being the two eight-inch shell guns, which, in number and intensity of effect, are not comparable to the thirteen nine-inch shell guns.

If the distance were lessened, the broadside of nine-inch shell guns would in weight of metal alone be nearly double that of the thirty-two-pounder and eight-inch shell

guns.

On the spar deck are to be no broadside guns, but, in lieu thereof, seven shell guns, of ten or eleven-inch calibre, on pivots, and capable of being pointed around the circle in every direction.

An auxiliary propeller power will be placed astern, for which purpose the length of the ship must be adapted to its convenient reception.

The points of this ship will be:

1st. Cost of Construction.-This ought not to exceed the cost of an ordinary sailing frigate, with the additional expense of steam equipment.

The St. Lawrence cost about $350,000; and the cost of a suitable engine, boilers, &c., as furnished by Kemble, would be about $70,000;-total, $420,000.

The Susquehanna steam frigate cost very little less than $700,000.

Comparing the long range with that of the steam frigate.

New ship, seven pivot guns, 11-inch
Susquehanna, three 64-pounders..

940 pounds.

192

66

3d. Cost in commission.-Only greater than that of a sailing frigate when steam is used, the crew not exceeding six hundred men, which is about that of the Congress frigate.

Comparing such a frigate with the heaviest steam frigate, it will be seen that the advantages are, far greater superiority in range and force, as the propeller frigate opposes seven 11-inch shell guns to three 64-pounders, the relations of which are about those of the 9-inch to the 32-pounders; and though her speed by steam is not equal, yet if the steam frigate once commit herself to the chances of a combat she will be beaten, for her motive power is far more vulnerable in nearly every point, and if deranged in the least by any of the contingencies of an engagement, she is at once exposed to the nearer approach of the propeller, and consequently to the full effect of the broadside guns, while her opponent loses but an auxiliary power, if any of her machinery be touched, her defence being made good against the steamer at any distance or position which the latter may select.

If opposed by the ordinary line-of-battle-ship with the present armament of 32-pounders and 42-pounders, the propeller frigate may, at a long range, play her seven pivot guns with comparative impunity, or she may close and bring into action the whole broadside.

Of course it is not designed to assert that the navy would be constituted of this force exclusively, but only that on such a class of ships reliance might safely be placed for defence of the coasts and harbors against any of the heaviest ships in foreign service. In time of peace they would cruise as flag-ships, while the inferior classes might receive pieces of such calibre and number as would be suitable. The second class would be ships with a light deck over the battery and a pivot gun on the to'gallant forecastle and poop.

The third class, ships with a light deck over a broadside battery, or else neither light deck nor broadside pieces, but heavy pivot guns to the extent of the accommodation.

All the vessels of lower rate to be steamers of five hundred to one thousand tons, mounting two pivot guns.

Query 3. Is it necessary or expedient to continue the system of fortifications on the shores of the northern lakes?

It would be a loss of expenditure already incurred not to finish the works which have been commenced on the northern frontier, and these would certainly be useful in the initial operations of a war; though there can be but little doubt that if it ever becomes necessary to direct the military operations of the United States to that quarter, the population of the States that border thereon would furnish a force fully sufficient to a prompt and final issue against any army that could be sent from England. It may indeed be questioned whether any decent opportu nity for severing a connexion so expensive and unproductive would not be very acceptable to the government of Great Britain.

I have the honor to be, very respectfully, your obedient servant,

Hon. C. M. CONRAD, Secretary of War.

JNO. A. DAHLGREN, Lieutenant United States Nary.

F.

Order to the Chief Engineer.

WAR DEPARTMENT, April 17, 1851. The chief engineer will please prepare and report to the department the information called for by the second of the enclosed resolutions.

He will also, at as early a period as practicable, submit to the department his views and opinions on the subject embraced in the first of these resolutions, and will request Colonel Thayer, Lieutenant Colonel De Russy, Major Delafield, and Major Chase to submit to the department their views and opinions in relation to this subject.

It is desired that the chief engineer and the above-named officers should direct their inquiries particularly to the following points:

1st. How far the invention and extension of railroads have superseded or diminished the necessity of fortifications on the seaboard.

2d. In what manner and to what extent the navigation of the ocean by steam, and particularly the application of steam to vessels-of-war, and recent improvements in artillery and other military inventions and discoveries, affect this question.

3d. How far vessels-of-war, steam batteries, ordinary merchant ships and steamers, and other temporary expedients, can be relied upon as a substitute for permanent fortifications for the defence of our seaports.

4th. How far the increase of population on the northern frontier, and of the mercantile marine on the northern lakes, obviates or diminishes the necessity of continuing the system of fortifications on these lakes.

C. M. CONRAD, Secretary of War.

The CHIEF ENGINEER.

No. 8.

Report of Lieutenant Colonel R. E. De Russy.

FORT MONROE, VIRGINIA, July 26, 1851.

SIR: Being called upon by the instructions of the Hon. the Secretary of War to present my views and opinions on certain points specified in his letter to the engineer department of April 17, 1851, I beg leave to place before you the following observations upon the subject, which I request you will lay before the Secretary of War.

Fortifications had their origin with the Greeks, and have been adopted, improved, and perfected by all civilized nations from that time to this. They long since have become a combination of sciences, involving mathematics, pyrotechny, strategy, and the art of war. The objects of fortifications are to make strong by art what otherwise would need an accumulation of active physical means, as also to protect exposed positions from sudden assaults of an enemy. In producing the first result, they leave at the disposal of the country invaded or attacked an active force which otherwise might be kept in check by an equal or superior one. Again, they secure in a great degree, within certain distances, positions rendered important either by their location or the magnitude of their commerce and resources; hence all important seaports should, in my opinion, be protected by suitable fortifications.

1st. Because otherwise an enemy's fleet might for a time with impunity ride