Length, overall, 53 feet 10 inches.

Diameter (beam) frame No. 19, 10 feet 3 inches.

Height, bottom to superstructure deck, 10 feet 7 inches.

Displacement, submerged, 74 3/16 tons.


All transverse sections circular.  Plating of steel laid in eight strakes. Thickness, 6/20" forward, 7/20" amidship, 5/20" aft.


Longitudinal seams, double staggered riveted lap joints, steel rivets.

Butt joints planed, with double riveted steel straps, 15-lbs. per square foot, steel rivets.

Circumferential seams, plating to frames, single riveted, liners under outside strakes.


3 ˝" x 3" x 6.7 lbs. steel angles, from frames five to thirty inclusive.  Remaining frames 3" x 2 ˝" x 5.6 lbs. Spacing 18 in.


And deck beams, 2 ˝" x 2 ˝" x 5 lbs. steel angles.


Steel plate, 15 lbs. per square foot, forward and aft; others 10 lbs. per square foot.  All sufficiently braced for the purposes of the ship.


Of steel, 15 lbs. per square foot for machinery and armament spaces.  Floors with reverse framing at each frame under machinery and battery spaces.  Deck under expulsion tube having floors sufficient for the needs of the ship.


Of steel plate under decks and at sides of ship, consisting of ballast tanks, to bring when filled, the ship to an awash condition; forward and after trimming tanks, forward tank for gasoline, and compensating tanks for weights received or expended are provided.

Storage battery being installed in steel tank.

All of sufficient strength and stiffness for the purposes of the ship.

Manholes are provided for access to the various tanks.


Of steel plate, 7 ˝ lbs. per square foot, with frames of 2 ˝" x 2 ˝" x 5 lbs. Steel angles, spaced 36" apart. A clear deck space is provided 37 feet in length; greatest width 3 ft. 7 ins.with ample cleats for mooring the ship, and locker for anchor and chain.

Scuppers are provided, of sufficient area to allow superstructure to fill quickly.


Two set are provided; a pair in a vertical plane, for horizontal steering; a pair in a horizontal plane for diving and rising, all constructed of steel, 10 lbs. per square foot, two plates to a rudder, sufficiently braced, and posts of ample strength for extreme angles of movement.


Of steel plates, with stiffening and supporting angles, of sufficient strength to carry the rudders and their posts in all positions of movement.


Of bronze, one inch in thickness, with a clear opening in top, 18 inches diameter, closed by a hinged cover, closing against a rubber gasket, and secured by a toggle locking device.

Ports or peepholes, covered with plate glass are provided, arranged to allow observation by the navigator in all directions.

Conning-tower arranged to allow installation of telescopic section, with means of raising or lowering.


Of steel, of sufficient strength for the purposes of the ship. Collision bulkhead located at frame No.29.


Of steel, trussed, spaced 30 feet apart; height 9 ft. 6 ins. above deck ofsuperstructure, arranged to allow observation of movements of vessel when submerged to small depths.



Of cast iron, 4 ft. 5 ins. diameter, 2 ft. 9 ins. pitch, left hand; driven by steel shaft, 4 ins. diameter. Speed 300 revolutions per minute.


Otto, gasoline type, with double cylinders, each single acting, giving a total of 45 horse-power at 340 revolutions per minute, and consuming about one pint of gasoline per horse power per hour.

Gasoline tank, frames 22 to 29, has capacity of 1,050 gallons, allowing a run of ship for 185 hours at full speed, this being 6 miles per hour with this power.


Electric, waterproof type, of 50 horse-power (nominal) with two commutators.  Capable of developing 160 horse power, giving the ship a speed of 8 knots.  Speed of motor 900 revolutions per minute.

Motor arranged to operate propeller shaft, or, driven as a dynamo, to charge storage battery.


From motor to propeller shaft, and engine to propeller shaft, provided with suitable clutches to allow the following combinations: Engine to propeller; engine to dynamo (motor); motor to propeller; motor to engine (for starting engine).  All gears covered with sheet iron cases.


Of ample length for continued running; stern bearing of lignum vitae, others babbited or bushed with bronze.  High speed shafting provided with self-oiling bearings.


Sixty cells, with a capacity of 900 ampere hours under normal rate of discharge.  Installed in a steel tank between frames 14 and 24.  Battery may be charges by main dynamo or from supply outside of the vessel.


Are provided, together with safety appliances, to control the current used for power and lighting.

Main motor provided with controller and ‘field rheostat.’  Auxiliary motor provided with starting rheostat.


Of best insulated wire, installed with view of insulating system from the hull of the ship.  In no case is the hull used as a return on a circuit.


Arranged to distribute light to various points of the ship.  Portable incandescent lamps being used.


Comprises a series of water tanks, one located at each extreme position, forward and aft, for longitudinal trim, and ballast tanks amidship of sufficient capacity to change the ship from the position for surface running to that awash, with a portion of the conning tower emerged, this being the condition for diving.  Means are provided for blowing the water from the tanks outboard, by air, or by pumping.  Outboard communication from tanks secured through 8-in. and 4-in. Kingston valves, opening outward against the pressure of the surrounding water, and operated by levers in the ship.  Valves have sufficient area to quickly fill or empty these tanks; all tanks with outboard connections are of sufficient strength and stiffness to withstand the pressures of extreme depths, if the valves be opened at these depths.  All tanks having for part of their bounding surfaces the plating of the ship, are provided with cemented bottoms, up to the height of the webs on the frames.


For torpedoes is provided, to keep trims of the ship constant at all times.


Is fitted with suction float, and necessary index of quantity of gasoline carried.

Compensation is provided to preserve the trim of the ship during consumption of gasoline.


One low speed compressor, driven through gearing, by an electric motor of 10 horse-power, furnishes air at 2,000-lbs. pressure per square inch, to welded steel storage tanks 13/16-in. thickness.  These tanks have a combined capacity of 22 cubic feet.
        All tubing for this system, of steel, and connections of sufficient strength for this pressure.

A supply of low pressure is secured through a tested automatic, reducing valve, with double diaphragms, supplying storage tanks at 50-lbs. pressure, one having capacity of 4 1/4 cubic feet for the operation of machinery; and two with an aggregate capacity of 5 1/2 cubic feet for expulsion of torpedoes.

Low pressure tanks, 10-lbs. per square inch, are provided for blowing out ballast and trimming tanks, and emptying torpedo expulsion tube.


One Bilge pump is provided, geared to and operated through clutches, by the 10 horse-power motor, driving the air compressor.  Through suitable connections this pump will empty any or all tanks, in addition to bilges.

One small hand-pump is provided to empty the storage battery drip tank, the latter being located to free the tank of any fluid.

One duplex, air-driven, reciprocating piston fluid pump, to operate steering and diving engines, exhausting its air into interior of ship.


Of suitable strength for the pressures used; with all necessary valves and connections to secure quick
manipulation of the various systems.


Engines are provided with reciprocating pistons attached directly to the leads.  Cylinders are of sufficient size to provide quick movements to the rudders.

Motion of pistons so regulated, that the rudders are locked in the desired position.

Through a series of connections, the navigator controls the steering and diving engines from the conning tower.

Hand operation of each of these engines secured by turning a valve.

The diving engine is provided with an automatic device, to govern the controlling valve; a diaphragm to keep the ship at a constant depth; a pendulum device to maintain a horizontal position and apparatus to bring the ship from an inclined or diving position to a horizontal position at a predetermined depth; this being accomplished by reversing the diving rudders, to a rising position during the period of diving, at a time previous to reaching the desired depth; reaching this depth cuts out this reversing mechanism, leaving the ship under the control of the diaphragm and pendulum until a time when the navigator desired to rise or proceed to a greater depth.


All indices are provided to record all conditions of the ship; pressure and depth gauges, clinometers, etc., are provided.


The exhaust of the air-powered machinery is distributed throughout the ship: connections to storage tanks are arranged to allow a supply of air into the boat, at will.  Several openings are arranged to provide the interior of the boat with outside air when at the surface.  The engine space is provided with ventilator, with electrically driven exhaust fan; openings in conning tower at end of gun, and several port openings allow a circulation of air through the ship.

Excessive pressure of atmosphere in the interior of the ship is relieved through a safety valve installed for this purpose.

Exhaust gases from the main engine, are carried through a water jacket, directly to the outside of the ship and lead aft to exhaust boxes at the stern.


Is supplied for all of the operations of the ship.  The conning tower being provided with rudder indicators for steering and diving rudders; clinometer for transverse and longitudinal trims; whistle cord, for outside signal whistle, bell pulls and speaking tube for communication with engine room, and other parts of the ship.  The compass is conveniently placed in the conning-tower and at all times is visible to the navigator.

Gauges for depth of ship, pressure in pipe systems, and quantities of water in tanks are situated at suitable points.   The gasoline tank having a special gauge.


Consists of one 'lower deck tube, Type 2, for 45 cm. x 11-ft. 8-in. White-head torpedo,' constructed after the plans of the Bureau of Ordnance.  This is placed at the extreme forward end of the ship, opening outboard, 3 feet below the light waterline.  The cap is hinged, lifting upwards and operated by worm gearing from inside the ship.  Cap make a water-tight joint when closed against a rubber gasket.

Air at 50-lbs pressure per square inch is used for expulsion of torpedoes.  Ten pounds per square inch being used to empty expulsion tube of water.

The ship has the capacity for carrying three 45 cm . x 11-ft. 8-in. White-head torpedoes, and means of compensating for each and every one.

One bow gun with fixed elevation for aerial discharge of high-explosive shells.  Projection secured through varying combination of compressed air and explosive powder.

The ship and all its apparatus have been thoroughly and continuously tested and operated; extremes in speed having tested the strength and durability of the propulsive machinery; extremes in depth having tested the strength of the hull, all tanks and valves connected outboard; this is coupled with the tests of an experimental model, constructed to measure the resistance of such a hull to collapse at great depths; extremes in steering testing the strength of the machinery for that purpose repeated expulsion of torpedo testing the tube and its devices, and the operation of all the above apparatus, to a degree of fineness, hitherto unknown in navigation and engineering.

November 24, 1899