D. OFFICE ENGINEER-In-chief, U. S. N., November 14, 1851. SIR: In the interview with which you honored me a few days since, you were pleased to ask in what manner the efficiency of the United States steam-frigate Mississippi could be increased without incurring any great outlay. In reply, I briefly sketched the mode by which a very great increase of efficiency could be obtained at little or no immediate cost. I have now the honor to lay before you more in extenso, but still briefly, the grounds on which my opinions were based, and to ask for them an attention which I feel assured they merit. The Mississippi was designed or planned in 1838-39, nearly fourteen years back, since which period great improvements have been made in the machinery of ocean steamers, by which means their speed has been nearly doubled, without retrenching the capacity of the vessel for carrying. The principal improvements have been made in the boiler. It is hardly necessary to observe that the power of a steamer is measured by the power of its boiler, and that the power of the boiler (other things being equal) depends upon the area or amount of its heating surface. Now in order that a steamship may perform the duty she is intended for, (for instance, if an armed steamship to carry the crew, battery, stores and provisions that will enable her to keep the sea a reasonable length of time, with equality of force to fight. an enemy of equal size,) only a certain portion of her capacity can be allotted to the engine department. In this portion must be comprised the engines, boilers and fuel; and in order to be able to keep the sea a reasonable length of time, the steamship must carry, at the very least, fourteen days' supply of fuel. It thus becomes impossible to give a boiler of any larger bulk than would allow sufficient remaining space for the engines and fourteen days' fuel in the portion of the vessel allotted to the entire engine department. The grand problem, then, is to devise a boiler which shall contain the maximum heating surface in the minimum space. This problem has been solved successfully by the invention of the "Lamb & Summer" boiler, which is the kind authorized by the department for the United States steamships Princeton and Alleghany, now in progress of construction, and which is the most superior type known. The present boilers of the Mississippi, designed fourteen years ago, are of the old-fashioned flue variety, the flues being sixteen inches in diameter, with large arches beneath. The proportions of these boilers are also so defective, that they are notoriously greatly wasteful of fuel, one pound of coal evaporating in them only 4.78 pounds of water; when in boilers of improved construction, one pound of coal evaporates eight pounds of water; accomplishing a saving of about forty per centum. The boilers of the Mississippi contain six thousand square feet of heating surface. Those now being constructed for the Princeton and Alleghany contain five thousand six hundred square feet of heating surface, or nearly the same. The Mississippi's boilers occupy on the ground plan, including eight-feet fire-rooms, fifty feet in length by twenty-eight feet in width. The similar dimensions occupied by the boilers of the Princeton and Alleghany are thirty-three feet in length by twenty-two feet in width, or the superficial areas compare as 1400 to 726; or, in round numbers, the boilers of the Mississippi, containing the same heating surface, occupy double the space in the vessel which is occupied by those of the Princeton or Alleghany. The Mississippi now stows in her bunkers six hundred tons of coal, which, at her consumption of forty tons per twenty-four hours, would give her fifteen days' steaming. If now we were to throw into bunker room the difference of lengths of the two kinds of boilers, viz: between fifty and thirty-three feet, or seventeen feet, we should be able to carry one hundred and twenty tons more of coal, which would increase the efficiency of the vessel from a fifteen days' to an eighteen days' steamer. The present boilers of the Mississippi, including water, &c., weigh two hundred tons; the proposed boilers would weigh, including water, &c., one hundred and twenty tons, or eighty tons less, which deducted from the additional amount of fuel to be carried, leaves forty tons more weight in the vessel, which would increase her draught two inches only; a small increase upon 18 feet, her present mean draught. Were the proposed boilers made of the same width of front as the present ones, which is contemplated in the above calculations, they would have a heating surface of seven thousand square feet, or one-sixth more than at present. By using, however, a modification of the boilers of the Princeton and Alleghany, and employing two stories of furnaces, twelve thousand square feet of heating surface can be disposed in the present front of boilers by twenty-five feet in length, and the power of the vessel doubled. Also, by reason of the greater evaporative effects obtained by the proposed boilers, this double power would be obtained by the consumption of but little more than the present consumption of coal. The present boilers are of copper and weigh 268,000 pounds. Their value as old copper, estimated at the low rate of 15 cents per pound, would be $40,320. The largest price paid by the Government for the improved "Lamb & Summer" boiler is 18 cents per pound; and as they would weigh for the Mississippi 165,000 pounds, they would cost $29,700, leaving a margin of $10,620 for contingencies. The results, then, of substituting the improved form of boilers, would be: 1st. The carrying of fuel for 18 instead of 15 days' steaming, or a gain of one-fifth. 2d. Doubling the power of the vessel, with sensibly the same expenditure of the fuel as at present. 3d. The cost of the substitution would be more than defrayed by the sale of the old boilers at their value as old copper. In conclusion I would add, that though the above figures and calculations are in round numbers only, yet the variations from them, which would be shown by the detailed plans, would be so trifling as not to sensibly affect the results. Believing this communication to deserve more than a passing notice, I have the honor to remain, sir, With the highest respect, your obedient servant, Hon. WILL. A. GRAHAM, Secretary of the Navy. Part ii-3* 1 E. U. S. NAVAL ACADEMY, SIR: The board for the examination of midshipmen, convened by the order of the department of the 10th of September ultimo, having completed that business, then proceeded to fulfil the duty required under the order from the department of the 29th ultimo, directing the board of examiners. "to examine into the state of police and discipline of the Naval Academy, and into the management of the institution generally, and report the result to the department." The subject of inquiry which first engaged the attention of the board, relates to the physical wants, the health and moral condition of the midshipmen; the object of all police regulations being the attainment of these important results. The houses in which are the recitation-rooms, the lavoratory and chemical lecture-room, as well as the hospital and one or two frame buildings in which a portion of the midshipmen are lodged, are old structures that originally occupied the ground, without any settled plan for their arrangement, previous to its occupation as a naval academy The officers who have been in command of the institution at different times since its foundation, have made such a disposition of these houses as seemed to thein most necessary and proper. In this they have been successful. Every advantage of which these are susceptible, has been obtained. The Under the present superintendent, a plan for the location of the new buildings (soine of which are finished and occupied, and others in a state of construction) was submitted and approved by the department. In relation to them the board has great satisfaction in being able to say that their location is good, and the arrangement and size of the rooms for the different purposes for which they are intended, are convenient and proper. board would, however, suggest some additional ventilation for the quarters of the midshipmen. One of the new houses is occupied by the lyceum and mess-hall. The latter exhibits the appearance of neatness and order. The food is good and abundant and the cooking judicious. The person who has charge of this department fulfils that duty satisfactorily. The building used at present as a hospital is well situated and conveniently arranged, with every appliance that can be necessary for the accommodation and comfort of the sick. There were no patients in the hospitalconclusive evidence of the zeal and intelligence of its present chief, as well as the salubrity of the situation. It does not appear that any provision is made in the present arrangement, for a bath-house. The board is of opinion that such a building, calculated for hot and cold baths, is essential and necessary to the health and comfort. of the acting midshipmen. The board would also reccommend that the grounds and buildings of the institution be lighted with gas, made on the premises. It is believed that it would be more economical and safe than the present mode with oil, besides possessing many other advantages. The routine of study, exercises, and recreation, is as follows: Before breakfast the students are required to make up their beds, and clean out their rooms. The attendants supply water, brush shoes and clothes, remove water from the rooms, scrub them out when necessary, keep the pas sages clean, and attend generally to the quarters, grounds, and pavement around them. At 7h. 15m. a. m. the students attend prayers, and at 7h. 30m. go to breakfast. At 8 a. m., recitations commence and continue until 1 p. m.; are resumed at 2, and continue until 4 p. m. From 4 p. m. until sunset, exercises either at great guns, small arms, sword or field artillery. Immediately after dress parade the students go to supper. Dinner at 1 p. m. during the session. Study hours from 8 a. in. to 1 p. m., and from 2 to 4 p. m., and from 7h. to 9h. 30m. p. m.; at 10 p. m. the lights are put out, and the students are not permitted to leave their quarters during the night, except for necessary purposes. One attendant is allowed for eight rooms; two students occupy one room. Each room is furnished with two bedsteads, two bureaus, two chairs, one table, wash-stand, lamp, oil and fuel. During study-hours the students are not allowed to visit each other's rooms, or to leave their own except when necessary. The rate of compensation to the steward is regulated every quarter; at present it is eleven dollars per month for each student. The passed midshipmen acting as assistant professors, also perform duty as police officers. The one on duty is called "the officer in charge." He presides at the mess-table, and preserves order. At each table the captain of a gun's crew presides, and is responsible for the good order of the crew while at table. The whole number of students is divided into guns' crews of fifteen each; this organization is preserved at roll-call, mess-formations, exercise of great guns, and dress parade, and to some extent in the exercise of small arms, but cannot be observed at the exercise of field artillery. There are no academic studies on Saturday, but the forenoon of that day is devoted to military exercises. The afternoon is devoted to recreation, one-half the students being permitted to visit the city, and the other half allowed to sail or row boats, or amuse themselves about the grounds of the academy. The store-keeper issues to the students every Saturday, such articles of clothing, &c., as the Superintendent may have authorized. The per-centage allowed to the store-kecper upon the articles issued is fixed by a board of officers and approved by the Superintendent. The board attended the recitations of the midshipmen and acting midshipmen, and their exercises with great guns, and at target-firing, infantry drill, and fencing. The mode of instruction pursued appears judicious, and the proficiency of the midshipmen and acting midshipmen, who have been here one year, in the exercises with swords, small arms, and great guns, particularly the target firing, gave evidence of the care bestowed, and the nterest felt for the advancement of their education, the preservation of their health, and regard to their comfort, highly creditable to the Superintendent and other officers of the institution. The mess-room is not considered large enough for the increased number midshipmen and acting midshipmen who have joined the academy during he last year. The board would, therefore, recommend the adoption of the plan for its enlargement, agreeably with the suggestion of the Superintend at. In view of the increase of the academy, the board recommend the purhase of the square of ground adjoining it, if it can be procured at a reanable price. On the street between this square and the academy, there is a row of small wooden buildings, mostly occupied by free negroes. Their proximity to the quarters of the officers on this street, increases the risk from fire very much; besides, with the increase of the academy, there will not be sufficient room within the present limits for the additional buildings that will be required, and for the different exercises of the midshipmen and acting midshipmen. The board would here suggest the propriety, as well as justice, of placing the secretary of the institution, in respect to pay, on the same footing as that of first clerks to the comma..dants of the principal navy yards, since his duties and responsibilities, by reason of his being required to perform also the duty of check clerk, are at least as onerous as those pertaining to first clerks. The discipline maintained at the institution is of a very judicious character, and, in the opinion of the board, is admirably adapted to the attainment of the object in view in establishing the academy. The restraints upon the youths committed to the charge of the Superintendent, are no more than are essential to the attainment of that object and the moral and physical well-being of the midshipmen and acting midshipmen. The practice ship, affording, as it does, so admirable a means of improvement to the midshipmen and acting midshipmen during the vacation in the summer months, is, in the opinion of the board, an excellent feature in the arrangements made by the Navy Department for forwarding the professional knowledge of the youths committed to its care. The ship is kept in good order and condition, and in constant preparation for any service the department may require of her during the intermediate periods. The board cannot conclude its repor without expressing its gratification in the existence of an institution promisi. g, as this does, such great and permanent advantages to the naval service of the country for the future; and its hearty approval of the judicious measures that have been adopted by the Navy Department for the faithful and efficient carrying into effect the patriotic views of the national Congress. I have the honor to be, sir, your obedient servant, To the Hon. WILLIAM A. GRAHAM, D. CONNER, Secretary of the Navy, Washington. President of the Board. F. NATIONAL OBSERVATORY, SIR: In illustration of the practical advantages to commerce and navigation, of the investigations that are carried on at this office, with regard to the "winds and currents" of the sea, I have the satisfaction of making known the fact, that the result of these investigations, so far, has already shortened the passage hence, by sea, to California, not less than forty days on the average. According to the abstract logs, and other statistical information returned to this office, it appears that the average passage of the sailing vessels, |