given up No. 1 model for guns of size large enough to be of any use, for the reason it cos's too much to make them and they are liable to be broken in firing, and they could hardly be built to supply air for 6 or 8 inch guns at any reasonable expense, and they would be too cumbersome. I will say I have improved the general set-up and mechanism in my No. 2 gun, so it is perfect enough to prove exact. Uniform results can be had in firing, and by my new method of firing an important improvement is, I am sure. I have gained a most tremendous increase of pressure or power with the same amount of gunpowder; further, I have satisfied myself that gunpowder is good enough and equal in power, if not more powerful than gases or vapors from liquids, which can e used if desired in the place of gunpowder; but I shall recommend a charge to be used (or a special cartridge) which contains no gunpowder or its ingredient not to get more power. I have enough with gunpowder, but merely to create less smoke and fouling in the compressing or powder tube. I will say that it will be a charge of guncotton made up to fit these guns, providing your Board consider it better than gunpowder (I myself do) for reasons above. I will say my model, now ready, has a ‡ inch bore shot tube, and has fired lead bullets 4 inches into solid wood by air compressed, the instant of firing, by exploding a charge of gunpowder and the pressure of gas created fol lowing on up after the air, while the wad and all following matter is driven to a separate art, from which it is removed occasionally, or should be each time; with the gun-coton charge, once in twenty-five times to brush out the tube will be sufficient. The diaphragm head or valve is not blown out any more when firing, as I have descr bed already. The air cushion against the projectile is very soft and perfect, creating no shock, and the report is more after the chew or puff of exhaust steam of a locomo tive than a sharp report of a gun. The head or safety valve always renders it perfectly safe from explosion, or from the bursting of the tubes. I will say I now have this gun mounted on a carriage (not wheels) swinging on trunnions, and with a screw for elevating the gun. There is a screw plug at the breech to insert the charge, and the valve or head in front is quickly screwed on and off to allow brushing out the lower tube; but still, for all this, the model, although built exactly as I say, is not a fine piece of machinery at all, but every screw and every part will be fully shown plain enough to copy to construct a nice gun by; and I will say I am to commence a gun with finely made mechanism, which with my means I can not have done for some time; and in the meantime I ask if the Board will examine what improvements I have made, or do you prefer to wait and see the better-made gun? I will say it has been a long and difficult work to get this gun to suit myself, but will now say I think my invention perfected. Mr. Whitney sent me an extract of your report; of course all I expect to be able to do now is to get private parties to take an interest in my invention, but if the Government wants it I will guaranty a perfectly made gun with fine mechanism; I wish, if you examine the gun now made, to know it is only a model designed to build a nice one by, but I warrant the firing to be perfectly illustrated to you; in this (without thinking of money) I think I have solved the problem to perfec tion for a practical "dynamite air gun." "If my request to have your Board examine the improvements in the mechanism or design of it, as above stated, 1 shall be prepared to show it to you at any time now; or if you desire to see a more perfect oue in mechanism I shall have to ask for more time. I thought you could see this now in New York or here in Lynn, and the other when that is done (which may not be until fall), which I warrant will be as fine a model as ever was made in this country, as some time and money will be spent on it. I will say vapors and gas can be exploded in this system as well as the other explosives named, and also work well; but I prefer the more portable powders and explosives.

SIR: Herewith are respectfully forwarded range-tables for the 5-inch B. L. R., with 1,700-foot seconds and 2,000-foot seconds, respectively.

The following is a description of the manner in which these tables have been constructed:

Gun, 5-inch B. L. R. No. 1.

Mount, 5-inch G. R. carriage No. 1.

Fired from range battery at Naval Ordnance Proving Ground August 18, 1887, and December 7, 1887.

Height of trunnions above mean tide level, 5.4 feet.
Elevations fixed by quadrant.

The jump was measured for every shot except 5, where the elevation was such as to render the use of a screen impracticable.

The powder used was P. V. A.

The charges were fixed by ten rounds fired August 10, 1887, as per firing sheet inclosed.

From these rounds the charges were established as follows: For 1,700 foot-seconds, initial velocity, charge, 23 pounds; for 2,000 foot-seconds, initial velocity, charge, 31 pounds.

A preliminary calculation was made fixing theoretically the angles of departure for the following ranges: 1,500 yards, 2,500 yards, 3,700 yards, 4,700 yards. These angles were used as angles of elevation in the firing.

Thirty-eight rounds were fired, or nineteen for each table, as follows: August 18, 18-7, at 1,00 yards, 2,500 yards, 3,700 yards, five rounds for each table; December 7, 1857, at 4,500 yards, four rounds for each table.

The line of fire was fixed by a stake planted on a shoal off Greensbury's Point, distant 1,400 yards from the gun.

The points of fall of the shots were noted by three plane-tables at ranging stations, and in a few cases, when the smoke allowed, by a theodolite in the line of fire in the rear of the gun. To allow the use of this theodolite a staging had been erected in rear of the guu, 35 feet above the level of the trunnions, in the hope that an observer stationed at that height would be able to see above this smoke. This hope was not realized.

The velocity and direction of the wind, the height of tide, the barometer and thermometer, and the relative humidity were noted.

The point of fall of each shot was plotted upon the chart and the ranges taken off. The mean range for each group was taken for the range for that group.

The angles for clevation were corrected for jump, and then, by the following method, for height of trunnions:

The angles thus found (by applying correction for jump and height of trunnions) are the "angles of departure" of the projectiles. From these angles of departure the ranges in vacuo were calculated by the formula

R

=

sin 2 a

where

V = initial velocity.

a = angle departure.

g=acceleration of gravity.

The observed ranges corresponding to the different angles of departure were then corrected for wind, by the following formula:

These corrections were applied to the ranges observed.

To reduce the ranges to mean atmospheric conditions (Bar. 30.00, Ther. 62) the range for each angle of departure used was determined, theoretically.

In previous range-tables the mean jump has been determined by several rounds fired at level, and the jump assumed to be uniform for all elevations.

W

(page 58, Meigs-Ingersoll's Exterior Ballistics) and S=Sv-Sq.

(page 61, Meigs-Ingersoll's Exterior Ballistics.)

(2) For the atmospheric conditions existing at the time of firing by the formula.

W=weight cubic foot of air under actual atmospheric conditions=;

(page 37, Meigs-Ingersoll's Exterior Ballistics.)

B=Barometric height.

534.22XB 1+.002178x130.00

t=difference between actual temperature and standard temperature. The differences between the theoretical ranges as above determined, first for standard and second for actual atmospheric conditions, give the corrections to be applied to the observed ranges to reduce them to ranges under standard atmospheric conditions.

These corrections were applied to the observed ranges as previously corrected for wind.

With the ranges thus corrected a curve was plotted, in the usual manner, with the angles of departure as ordinates and the ranges as abscissæ, and from third curve the angles of departure were taken off for every 100 yards of range.

With the angles of departure thus found, the remaining velocities and angles of fall were calculated for every 500 yards. (Exterior Ballistics, page 58, formula 47 and 48), and found by interpolation for the intervening points.

A second curve was now constructed with the angles of elevation as ordinates and the ranges corresponding as abscissæ, and from this curve were taken off the angles of elevation for every 100 yards of range, and also the range for every 30 feet of elevation.

The times of flight were fixed partly by observation and partly by calculation, the theory and practice being found to agree.

W weight of projectile.

d=diameter of shot in inches.

9 angle of departure.

(Page 55 and tables, Meigs-Ingersoll's Exterior Ballistics.)

The deflections were taken from the chart and corrected for force and direction of wind by the formula

in which

C=AB tan &

A correction for wind in direction of line of fire.

(already found and applied to range.)

B ratio between areas of transverse and longitudinal sections of projectile. a angle of wind with line of fire.

A curve was constructed with the deflections thus obtained, and from it the deflections are taken off for every hundred yards.

With regard to these tables as completed, I would say that they are very satisfactory to me except in one point of deviations. These, as observed, were not regular, and the column embodied in the table is the result of much more approximating and smoothing up of curves than I am able to accept without placing upon record a statement of the fact. This is a trouble which is more or less inherent in the nature of our range and of the situation of the station. We are compelled to take advantage for firing on occasion when the range is clear, and can not choose such conditions of weather as would be most suitable, though of course no firing is done on days conspicuously unsuitable.

The observation of a splash so large as that made by a 5-inch projectile is subject to inaccuracy, from the impossibility of getting all lines to converge at the center. In quantities as large as are the ranges, this and errors connected with the variations in the direction and force of the wind, and in the correction for the effect of the wind, are trifling, never amounting to more than a few yards, but in the deviations a few yards is very important.

With the exception of the deviations, the tables are, as already stated, very satisfactory to me. The observations have been uniform and have fallen into unusually smooth curves.

Respectfully, etc.,

CHIEF OF BUREAU OF ORDNANCE,

Navy Department, Washington, D. C.

AUSTIN M. KNIGHT, Lieutenant, Inspector Ordnance, in charge.

The telephone outfit to be supplied to ships for establishing communication between the ship and the shore or a boat consists of

Two or more miles of light, but strong and flexible, double-conductor cable, and two portab e boxes, each containing a magnetic call, a two-point switch, and a speaking and a transmitting telephone.

In using the apparatus, one end of the cable is run to the shore, sinkers being attached to the cable at intervals by means of snap-hooks to sink it. To prevent the fonling of the cable by the ship in swinging, a buoy is moored just outside the sweep of the ship, having on its moving line a weighted ring throngh which the cable is passed. The ring being let go slips to the bottom, carrying with it the bight of the cable. The portion of the cable between the buoy and ship is tended as necessary when the latter swings.

No. 8.-BUREAU OF CONSTRUCTION AND REPAIR.

NAVY DEPARTMENT,

BUREAU OF CONSTRUCTION AND REPAIR,

October 31, 1888.

SIR: In obedience to the Department's instructions I have the honor to submit my annual report for the fiscal year ending June 30, 1888, showing the work performed and the amount expended, together with estimates of the amounts required for the purpose of the Bureau for the fiscal year ending June 30, 1890.

The estimates for the expenses of this Bureau, as given in the statement marked A, are in accordance with existing laws.

An estimate is submitted for a chief draughtsman of this Bureau, this rating having been for several years allowed in the Bureau of Steam-Engineering.

Mr. William T. Powell, the present head draughtsman of this Bureau, is in every way qualified for this position, not only for his ability to make the calculations and carry out the practical work required in one holding so responsible a position, but also that, from his long experience in the designing of men-of-war, his opinion is of the greatest value in all that pertains to their fitting and equipment.

The establishment of the rating of chief draughtsman and the ap pointment of Mr. Powell to that position would be an act of justice to one whose long, faithful, and efficient services at a small rate of remuneration entitle him to a substantial advancement.

The estimates in statement marked C is for the pay of clerks and writers at the several navy yards whose services are indispensable for the proper and systematic prosecution of the work which is required to be done at the yards by the Bureau.

The estimate marked B is for the general repair of vessels at navy. yards and on foreign stations, purchase of stores, material, machinery, rights of patent articles, and tools of all kinds, preservation of materials and stores, and for the general care and protection of the Navy in the line of construction and repair; and the estimate marked D for the hulls and outfits of new vessels, and the improvement of the plants at the navy yards.

The Bureau recommends the immediate construction of experimental works to cost $60,000, for use in the determination of the resistance and other qualities of ships by means of models.

Such tanks as are recommended now form an invaluable and important part of the ship-designing branch of foreign naval establishments, and the Bureau is convinced of their permanent value in designing high-speed vessels and in analyzing the results of ships' trials.