In the annual number of the "General Information Series, No. VII," published by the Office of Naval Intelligence, appeared a most excellent article on the subject of "Electricity on Shipboard," by Lieutenant J. B. Murdock, U. S. Navy. While some of the ground that he covered must necessarily be gone over in this article, my idea is to enter more particularly into the details of the application of electric motors on board ship; showing where such applications can be made to advantage, and what particular types of motors are best suited for the different classes of work to be done.
LAYING OUT AND INSTALLATION OF PLANTS.
The importance of applying electricity to all of our vessels is now thoroughly appreciated by the Navy Department and by all naval officers who have given the subject any study. The office of "Naval Inspector of Electric Lighting" was established by the Bureau of Navigation over two years ago (in January, 1887), and its title should now be changed to the office of "Electrical Applications," since, in the near future, lighting will be but one of several uses to which electricity is put. While on this subject, it would seem appropriate to urge the importance of concentrating the control over all electrical appliances for ship use under one office. On shore, it is now a well established fact, proved by many disastrous failures, that an electrical plant of any kind whatever must be laid out systematically and progressively from the start, having in view the character of work to be done, distance to be covered, best arrangement of central station, etc. On shipboard, where every foot of room is valuable for some purpose, it is particularly important, first, that all generators should be concentrated in one place; second, that the generators and the wiring of the ship should be laid out with a view to all the work to be done, including lighting, power transmission, signaling, gun firing, torpedo work, etc. At present, each bureau of the Navy Department seems to have control (to a certain extent at least) of the electrical apparatus to be used by the department under its control aboard ship. If this system is carried out, the chances are that each bureau will get what apparatus it pleases, regardless of other bureaux, with the result of having on every ship three or four (possibly more) types of machines, many useless spare parts, and the occupation of more room than is necessary to get far better results. If the complete electrical installation of the ship is under one bureau, or office, whatever it may be called, then all of the practical information gained by former experience can be collected here; one man with proper assistance can lay out an installation with an intelligent knowledge of all the work that has got to be done and how it can best be done, and the work of installation can be properly supervised as it progresses. With such a system, we obtain the advantages common to a central station for light and power distribution on shore. By having the prime power bunched at a common station, one set of attendants suffices for the care of the machinery, one coal pile furnishes all the power, and where electric light and power are distributed in a number of units, the power required at the station (that is, the number of generating machines necessary) is much less than when each locality where the light or power is used supplies its own power. This is due to the fact that all consumers never use their maximum light or power at the same time; and it has been found in practice that central stations can actually rent more power to consumers than they have at the station. It is through a careful consideration and study, of these facts that the transmission of light and power on shore has become both practicable and profitable, and it is only by following the same principles on shipboard that success can be obtained.
What has been said concerning the necessity of having one head who shall design and install the electrical plant complete on board ship, applies with equal force to its proper care and maintenance in service. The ordering of officers to ships for special duty has always been looked upon with disfavor in our service. The time is rapidly approaching, however, when it will require about the whole time and service of one man to care for the electrical apparatus, high explosives, torpedoes, search lights and signaling apparatus of a large vessel, and it seems eminently proper to bring the matter up for discussion at this time, in order that those who have the efficiency and reputation of the service at heart can take the proper steps to introduce successfully into the navy that new agency for transmitting power which is making such rapid strides in commercial life.
If officers will take the subject up on a broad and liberal basis, electricity will rapidly replace steam on board ship and at our navy yards for many of the auxiliary purposes for which the latter is now used, and will replace it with a great saving in first cost, with a much greater practical success in operation, and with greater comfort and satisfaction to those who have to live on board ship.
If, then, we are really desirous of obtaining the benefits arising from the substitution of steam or hand power by electricity in the navy, the following plan should be adopted:
1. The designing and laying out of the complete electrical plant for a ship or navy-yard should be done at one time and place, and under ONE head. Whether this head should be under one of the existing bureaux of the Navy Department, or whether he should have charge of a separate office, responsible only to the head of the Navy Department for his work, is a question which must be decided by those in authority, but it is a question which should be decided before the plants for all of our new vessels are required.
2. While a plant is being installed and when it is put into operation, ONE man should have charge of all electrical appliances, and he alone should be responsible for their proper care and maintenance.
THE ENGINES AND DYNAMOS.
In considering a combined light and power plant on board ship, the electric generators and their driving engines must be studied. The experience of the past five or six years in ship lighting has placed in the hands of the Navy Department so much valuable information concerning electric plants for ships, their practical working, their defects, and the requirements which the service imposes, that the specifications for plants to be used on the new cruisers can be drawn up minutely and accurately, and it can be safely assumed that the various electrical companies in the United States can successfully fulfill all the conditions imposed. Briefly, the dynamo room must be considered as one of the vitals of the ship (as are the engines, boilers, and magazines), and as such should be as thoroughly protected as the type of ship permits. The plant should possess compactness, lightness, strength, simplicity of construction, absolute interchangeability of parts, and, finally, economy. The experience gained in this country and abroad seems to point to the use of compound, condensing, high speed engines, coupled direct to low speed, multipolar, compound wound dynamos of high efficiency and constant potential. The plant should consist of two or more engines and dynamos. The engines as well as the dynamos should be duplicates of each other, and should be sufficient to operate the maximum number of lights and motors that would be used at any one time. As the load varies during the day, dynamos can be shut down or started up as required. The total output of dynamos need not be the sum of all the horse-power represented by the motors and lights in question. Central station experience on shore has demonstrated the fact that when there are many motors operating from the same station, only about 33 per cent of the power represented by these motors in the aggregate is actually required at the station to operate them. This is due, of course, to the fact that the motors are never exerting their maximum power at the same time. The same thing will be true to a certain extent in the case of motors on board ship, and it would seem unnecessary to allow for the dynamo capacity more than 6o per cent or 75 per cent of the total maximum power represented by those motors that will be in use at any one time, plus the lights required at the same time. Economy in coal consumed, for a plant of the size necessary for our large ships, dictates the use of compound engines; and the ability to operate incandescent lights, search lights, and motors from the same circuit would seem to indicate the desirability of compound wound dynamos. As before stated, these points were discussed very fully and clearly in Lieutenant Murdock's article.
The voltage used should not be less than 8o volts if motors are to be used on the circuits. The lower the voltage the greater the current used by a motor of given horse-power (since horse-power is measured by the product of volts and amperes). In practice it is found undesirable to go below about 8o volts for motors of any size; the large current requiring large wire on the motor and a large amount of copper in commutators, brushes, etc., to prevent undue heating. The requirements of engines and dynamos for ship work are necessarily much more rigid and severe than those imposed on similar machinery ashore; at the same time, special conditions should not be needlessly imposed when the ordinary commercial requirements of an engine or dynamo will suffice aboard ship. A case in point occurred some time since. A special dynamo had been built for one of our men-of-war by one of the largest electric companies in the country. One condition imposed was that the field magnet coils of the dynamo should not rise more than a certain number of degrees in temperature under full load. The condition was very much more severe than that imposed by the company on their commercial machines. On the test the dynamo fulfilled the required conditions of load efficiency, non-sparking, etc., admirably, but the field coils slightly exceeded the limit in temperature. The dynamo was rejected, and being a special machine, it was virtually thrown on the company's hand. The dynamo would have done its work well, and the question of 4º or 5° Fahrenheit in the temperature of the field coils would never have been thought of again. Such a thing is naturally discouraging to a company when it is trying to aid the navy in creating a new type of machine to meet new and severe conditions, and it would certainly seem that the officer in charge of the government work should have some discretion allowed him in deciding on such a case. In order for a plant to be a success aboard ship the government officers and the manufacturers should work in harmony, each trying to give the other the benefit of experience obtained in previous work of a similar character. Hard and fast requirements cannot always be rigidly adhered to in a piece of machinery which has never existed before, and our officers should aid the efforts of the manufacturers whenever they can do so consistently with their duty to the government.
Too much care cannot be taken in this important branch of an installation. Upon it depends largely the success of the plant. Practical experience has shown the severe conditions that ship wiring imposes, and they can now be successfully met. The question of covering insulated wires with lead to protect them from mechanical injury or the deleterious influences of salt water, heat, and gases is one that should be thoroughly discussed. I very much doubt its value. On board the Atlanta the lead covering gave more trouble than almost anything else; in handling the wire the lead covering is almost sure to be more or less broken and bruised. A sharp point of lead will be forced into the insulation of the wire, sometimes touching the copper even, and a leak or even a short circuit between the positive and negative wires is the result, since the lead covering is in contact with the steel bulkheads, etc., more or less. For the first six months after the ship went into commission, two or three men were kept constantly employed in removing sections of this wire and putting in new sections without the lead covering. In the engine and boiler room, and especially over the boilers, the insulation on the wire deteriorated very rapidly inside the lead covering, leaks and short circuits being the result. If the insulated wire needs a mechanical protection, it would seem that an armoring such as is used on submarine cables would be better than the lead covering. The following plan for laying out the wiring of a ship is suggested by experience on shore:
The mains to run fore and aft under the armor deck, and as much below the water-line as possible. There should be several parallel mains connected at intervals by cross branches to provide for possible accidents to one or more. The mains to be armored insulated cables run through tubes, or better, to consist of the regular underground tubes used so largely in many of our large cities to-day. They consist of bare copper wires or rods embedded in an insulating compound in the tube, the compound being run into the tube when liquid and allowed to harden. The tubes are joined together by water-tight junction boxes provided with screw plugs, which can be used for connecting on branch lines. The mains should be run while the ship is building.
Branch circuits running to the upper decks in each compartment should be run vertically wherever possible. A new system of house wiring has recently been developed which could be well applied to branch circuits. While a house is building, a series of flexible tubes of a tough insulating material are run behind the walls and ceilings. When the wiring is to be done, darts, carrying light strings, are blown through these tubes, and the wires are then hauled through the tubes by means of the strings. The tubes being flexible, the wires are not hauled around sharp corners or bends, and they are thoroughly protected from water or gases.
For the engine and boiler rooms circuits, the same arrangement could be used, or what would perhaps be better, run the wires bare in continuous porcelain or slate troughs. There is then no insulation to be affected by heat, the wires can always be seen, there could be no danger to the men with only 80 volts pressure, and the porcelain or slate would form an admirable insulation from the steel hull and bulkheads.
All cut-out and junction boxes should be water-tight and as accessible as possible. About the upper decks, where water is liable to get at the wires, they should be run either in continuous water-tight tubes, or else be left in plain sight in porcelain troughs, so that they can readily be inspected or repaired.
The incandescent lamp is too familiar to need much mention. For ship use it would seem advisable to have as few sizes of lamps as possible. The saving effected by substituting a few 8 or to C. P. lamps for 16 C. P. lamps in certain places is very small, while the carrying of two or three sizes in stock means a good deal of unnecessary work in keeping them properly located and in keeping their various records. Ship lamps should have a short filament, on account of the danger of its breaking through vibration. Lamps should also be placed vertically rather than horizontally, for the same reason. The number of search lights on board ship will be constantly increased, probably, on our larger vessels, and attention should be paid to improvement of the regulation and feed of these lights. With the type of light in use on board the Boston and Atlanta, one man is kept pretty busy attending to the regulation of the arc and the feed of the carbons. It would certainly seem desirable to have some automatic device introduced to relieve a man of this work. Such a device would tend to steady the arc, and reduce or do away with the necessity of inserting a resistance in the search light circuit to steady the fluctuations and not affect the incandescent lamps.
We now come to that application of electricity with which I am directly connected, and which I think gives such promise of successful introduction on board ship. I refer to the transmission of power by electricity. Probably no industry or business developed even in this progressive age has made such remarkable strides as the transmission and sale of electric power for commercial uses. Five years ago there was hardly an electric motor in use in the United States. To-day the single company with which I am connected has in use no less than 1200 stationary motors, aggregating over 5000 horsepower, and representing no less than 130 or 140 commercial industries; besides these stationary motors, we are now operating or building nearly 50 electrical street car lines, representing 200 miles of road and 300 cars; we are equipping a coal mine with motors to be used for tram work, drilling and coal cutting ; and we expect shortly to put in a 400 horse-power plant in one of the largest copper mines in the world. We are running whole mills entirely by motors; we are running dredges, incline hoists, and elevators, ventilating fans, ice cream freezers, and printing presses ; last, but not least, we have recently finished a shell hoist for the U. S. S. Atlanta, and our men are now fitting a training motor and an elevating motor to an 8-inch carriage of the Chicago. I say this merely to show to what extent the electric motor has already replaced steam, water, gas, heat, and other forms of engines for general commercial purposes, and that it is destined to still further supplant them is proven conclusively by the number of companies springing up all over this country whose sole business is electric power transmission. Mr. Sprague, with whom I have the honor of being associated, in an elaborate and interesting paper read before this Institute two years ago, described the theory of the electric motor, and the reasons why the transmission of power by electricity is so much cheaper and more efficient than by any other method. I do not intend to go into the theory of the subject, but rather to try and show how and why electric motors can be advantageously substituted aboard ship for many of the auxiliary steam and hydraulic motors with which our new ships are crowded. First, let me state briefly the two general classes into which successful electric transmission may be divided.
1. Where large units of power are transmitted over long distances (varying from 5 to 25 miles), and where the work to be done is concentrated in two or three units.
2. Where smaller units of power are transmitted over comparatively short distances for a large variety of purposes.
Ship work comes under the second class, and is by far the most common and widely used method of transmission. It is the system now used in all of our large cities, where central stations for the distribution of lights have already been established, and where the revenue to these stations from their sale of power is rapidly approaching and will soon surpass that derived from the sale of light. Independent power stations are also being established, stations where nothing but power will be sold. These facts are sufficient to prove that the electric motor has passed the experimental stage, and that its superior reliability, economy and efficiency are an established fact. Both the army and the navy are conservative where innovations or new devices are concerned, and properly so.
The officers are charged with the expenditure of government moneys, and they have neither the authority nor desire to develop new commercial enterprises. It is their duty to take advantage of these new enterprises when they have proven themselves successful and when they can be applied with advantage to either service. A bill was before Congress at its last session to appropriate a generous sum of money for the development of the electric motor for naval uses, and it is to be hoped that this action of Congress will receive the cordial approval and support of all naval officers.
The work required of the auxiliary engines of one of our latest type of vessels may now be divided as follows:
- Steam air and condenser pumps located in engine room, both for main and auxiliary condensers.
- Steam pumps for fire purposes, for pumping out the ship, washing decks, etc.
- Steam reversing engines for each engine.
- Steam engine for jacking the engines.
- Steam steering engine.
- Steam capstan engines.
- Blower engines for producing forced draught in the fire room.
- Ventilating engines for ventilating the living spaces below.
- Hoisting engines. Under this head are included steam ash hoists and hydraulic ammunition hoists.
- Steam winches about the decks for lifting heavy weights, swinging out boats, etc.
- Steam or hydraulic training engines for large guns.
- Steam engines for driving the dynamos.
- Steam engines for working lathes, drills, etc., in workshops.
Taken together, these auxiliaries will aggregate forty or fifty engines on a large ship, representing perhaps zoo H. P.
The engines, however, are never exerting their maximum power at the same time; hence if the work were done by motors, not over 60 to 70 per cent of this 200 H. P. (allowing liberally) would have to be provided for in the dynamo room.
Now I hold that the electric motor can replace every one of these auxiliary engines, and do so with a great saving in first cost and space occupied, and make the whole system of supplying auxiliary power cheaper, more efficient, simpler, and generally more satisfactory to every one.
It will be seen at a glance that it is necessary to distribute steam to every one of these auxiliary engines. Even the hydraulic machinery, very complex in itself, must have a steam engine to operate the compressing pumps. The engines are scattered all over the ship, from the capstan engine in the forward compartment to the steam steerer in the after compartment. To each engine it is necessary to run a separate steam and exhaust pipe. These pipes, varying from 3 inches to 5 inches in diameter, must pass through. water-tight bulkheads, at each one of which a water-tight packing joint must be made; they must bend and twist and turn so as to take up as little room as possible, out of harm's way; they must be heavily lagged wherever they pass through officers' or men's quarters; finally, expansion joints must be provided between rigid bulkheads, or there will be constant leaks at all joints and flanges or else buckling of the pipes. On board the Atlanta, for the first year after the ship went into commission, a gang of men were kept busy repairing leaks and breaks in the steam piping. On a ship like the Maine or Texas, the piping for the auxiliary engines will run up into the miles. The first cost of laying the pipe is enormous; it requires constant attention to keep it in good condition, and even when in good condition, the pipes are hot and cumbersome and the engine dirty and noisy. If repairs are to be made to engines, they must be made by a machinist; a machinist is necessary to operate the engines. If a steam pipe should be struck by a shot in action (and it would be a hard matter not to strike one), there would be a rush of steam at 8o or 90 pounds pressure within the compartment where the shot entered, which would probably seriously injure or demoralize the men in that neighborhood. The engine connected to that pipe (and it might be the steam steerer) would probably be useless during the rest of the fight.
As to the efficiency of these auxiliary engines, it is probably very low, taking into consideration the fact that there is necessarily much loss in the pipes from radiation, condensation, and back pressure, and that small, simple engines of the type necessarily used are notoriously wasteful of steam and uneconomical in operation.
The mechanical applications made necessary by the use of auxiliary steam engines deserve notice. The steering engine is located at the stern of the ship, where it can operate directly on the tiller. The steering of the ship must, for obvious reasons, be done from forward. The usual method of operating the valve of the steam steerer from the pilot house is to run a line of shafting from one point to the other; the shafting being operated either by hand or by another engine in or under the pilot house. On board the Atlanta this shafting passed along overhead on the gun deck, thence down to the berth deck and through the ward room, until it finally reached the steering engine. In this distance it made no less than eight changes of direction, necessitating sixteen bevel gears, besides clutch couplings for each of the three wheels. A 1-pound Hotchkiss shot coming in on the gun deck would knock the shafting out of line in a second, and the ship would then have to be steered by word of command passed along from the conning tower to the steering compartment. Another example of the cumbersome mechanical devices made necessary by the use of steam is the gun training engine for the 8-inch B. L. R. The engine for it took up so much room that it could not be put on the gun carriage. It was therefore put in a room by itself on the orlop deck, and connection was made to the carriage by a vertical shaft running up through two decks. The amount of power lost in friction and change of direction is great, and the executive officer's room was spoiled by having an ugly shaft running down through it. I mention these particular cases not to criticise the devices in themselves, but to show the non-adaptability of any system for ship use which makes such devices necessary.
Now, in what respects will the application of electricity be an improvement over the present system? Instead of the steam and exhaust pipes, 4 inches or 5 inches in diameter, being run all over the ship, we have in the first place our main conductors, running fore and aft, and secure below the water-line from shot and shell. The mains are perhaps one-half an inch in diameter instead of four inches. In each compartment where a motor is located, vertical branch lines are run to the motors and lights. These wires can be bent around corners or taken over or around obstructions at will. They require no elaborate water-tight slip joints at bulkheads; a half-inch hole with a small stuffing gland inserted is all that is needed. They require no lagging to make living quarters inhabitable; no expansion joints to prevent buckling of the bulkheads or leaks in the wires. The branch lines being run vertically, to a certain extent at least, present a minimum target to an enemy's shot. If a wire is shot in two, there is nothing to damage the men or create a panic among them; the most ignorant man aboard ship by a single twist can splice the break in a few seconds and the motor will run as well as it did before. In fact, nearly every objection raised to steam pipes is eliminated. When we come to the motors, the advantages are equally marked. For equal horse-powers the electric motor occupies less than half the space of the steam engine and weighs less. There is no heat or escaping steam about the motor. Any "idler" can operate it by opening or closing a switch; and beyond an occasional filling of self-oiling bearings and cleaning of the commutator, the motor runs itself. The motion is rotary instead of reciprocating, which means invariably much more quiet operation, less wear and tear of parts, and simpler mechanical applications. These are the advantages possessed by the electric motor that have led to its extended application on shore in place of steam. They are the same advantages which will be obtained by its use on board ship. Two questions which are commonly raised about motors on shore by persons unacquainted with them will doubtless be raised by some officers in the service. They are, first, can motors be made of sufficient size to do the work required of them? and second, can they be relied upon to do the work as well and with as few breakdowns as the steam engine? The first question can readily be answered by simply stating that the regular standard sizes of the motors made by the Sprague Company range from one-sixteenth of a horse-power to eighty horse-power, the list comprising forty or fifty types of machinery. In every case the rated horse-power is that delivered from the pulley of the motor. On all motors above five horse-power in size, the commercial efficiency to 90 per cent.
The second question is best answered by a reference to the commercial world, where hundreds of these motors, of all sizes and types, are running 8, to and 12 hours a day, every day in the year, and on which the repair account in many instances does not amount to $to for the year. It is in this direction that the greatest advance has been made in motors during the past three or four years. When they were, first introduced, troubles with the field coils, "crossed" or "burnt out" armatures, and commutators all cut to pieces by sparking and improper construction, were not of unfrequent occurrence. To-day such a mishap is extremely rare. Formerly, a motor was generally considered as a delicate piece of mechanism which must be kept under a glass case and labeled "handle with care." Today we put a pair of motors under a street car, and run the car through snow, slush, mud or rain, the car doing continuous duty for 16 or 18 hours out of the 24, and averaging from 90 to 120 miles per day. These facts speak for themselves. No service aboard ship can approach that required of a motor for street car service, either in variation of speed or load, length of continuous duty, suddenness of shocks, strains and jars, unfavorable conditions of weather, streets, inaccessibility and narrowness of the space allowed, and lack of even a small amount of attention. If we have a motor which is to-day successfully meeting and overcoming such conditions, is it unreasonable to predict that the same motor on board ship, where every condition is vastly in its favor, will do as well and better? The street-car motors are put under a car within six inches of the ground, and the car is operated by an ignorant man who cannot even see his motors, who cares nothing about them, and who cannot tell one end of it from the other. These motors run, not by reason of any fostering care on the part of the motor man, but in spite of him.
Salt water has always been regarded as a hated enemy of the electric motor or dynamo, until within the past few months; its omnipresence aboard ship would have been a serious objection to its use in many places. The same objection, however, had to be met and overcome in the street-car motor, and to-day we can actually soak an armature in a barrel of salt water, take it out, put it in a motor and run it. This is no idle boast, but a feat which has been actually accomplished. For some months the Sprague Company have been engaged in experimenting on a method of treating field coils and armatures with an insulating compound in such a manner as to render them impervious to water or acids. Recently an armature which had been put through the process was soaked for 24 hours in hydrant water. It was then taken out, measured, found to be sound in every respect, and then put into a barrel of salt water for 24 hours. At the expiration of this time it was taken out, put at once into a motor without a drying of any kind, and the motor was run for two hours on an overload varying from 25 to 50 per cent above normal full load. No test could be more thorough or convincing, none more satisfactory to us. In future, all of our motors subjected to the influences of the weather or to any unusually unfavorable conditions will be subjected to this process.
The class of work to be done by motors aboard ship may be divided generally as follows:
First Class.—Where the load varies, but speed of motor is constant—running lathes or drill presses, for example. For this work a differently wound, constant speed motor is most suitable. Such machines do not vary more than 2 per cent in their speed from no load to full load. In some cases, where constancy of speed is not required within 5 or 10 per cent, a simple shunt machine will suffice.
Second Class.—Where it is desired to vary the load and speed only through a limited range—running ventilating fans, hoisting, and some pumping, for example. Here a cumulatively wound motor is desirable. In this case the field coil, in series with the armature, acts with the shunt coil in its magnetizing effect instead of against it, and a variation of from 15 to 30 per cent in the speed can be obtained.
Third Class.—Where the load and speed vary widely, but where the motor is never without some load, as, for example, in steering, gun training, and certain pumping. Here a plain series motor is the most suitable. The torque or turning moment of a motor varies directly as the product of the ampere turns in the fields and in the armature; in a series motor the same current passes through fields and armature; hence the torque varies as the square of the current. This means that in starting under a heavy load, or in moving the load slowly, a series-wound motor is capable of exerting an enormous torque for a short length of time.
These four types of motors will cover every class of work that an auxiliary engine on board ship can be called upon to perform, and the motor will do it better in every instance than the steam engine. The electric motor, as compared with the steam motor, is much more compact and lighter; simpler in construction, application and operating; less noisy, cleaner, requires no skilled labor to operate it; is more reliable, more efficient, and less likely to get out of order. Every one of these points are points in its favor for ship use. Suppose the Atlanta had an electric motor instead of the steam steering engine she has (which, by the way, takes up a whole compartment and makes the after part of the ward room uncomfortably warm and noisy when in use). The motor would occupy about one fourth the space, the steam and exhaust pipes would be replaced by the mains below the armored deck, and instead of the long line of shafting running from pilot house to engine, a small controlling wire would run down from the conning tower through a small armored tube, and thence aft under the armored deck to the controlling switch of the motor. What a saving in first cost of installation, simplicity and ease of operation, and safety in time of action! Suppose the 8-inch gun training engine, occupying a room by itself on the orlop deck, was replaced by such a motor as the Chicago will have. The motor will be placed between the side brackets of the lower carriage and under: the breech of the gun. It will be so geared that by throwing a single clutch, either the motor or the hand-gear can be used. The long shafting running up through two decks is done away with, and the gun captain, with a simple lever in his hand, can train his gun with the greatest ease. I take pleasure in stating that the Sprague Company is now fitting such a motor (the first of its kind) to one of the 8-inch carriages of the Chicago. A smaller motor for elevating purposes is also being attached to the same carriage. At the same time, we have also put on board the Atlanta an ammunition hoist motor to be used in whipping up the 6-inch and 8-inch shell, and having attached to it a very ingenious hand control. The same hoist can be used for hoisting ashes or for any general hoisting. A power hoist is only advantageously substituted for hand hoisting where weights lifted are comparatively heavy (100 pounds or more), and where it is desired to handle them quickly, with a lift of say 25 feet or more. The principle of the floating lever as applied to steam ash hoists is well understood. Briefly, the man handling the hoist must keep a small crank or wheel in motion in order to keep the engine moving. If he stops turning the wheel, the engine stops. It he reverses the wheel, the engine reverses. This control of the hoist becomes very important in hoisting loaded shell, powder or high explosives. If a man is shot while hoisting, or if he becomes demoralized and lets go his hand wheel or ceases to turn it, the engine must stop at once; otherwise, the shell might be detached from the whip and dropped down to the shell room.
The new hand control carries out this principle fully. A man must turn a wheel in a certain direction to start the motor, and the speed increases as he increases the speed of rotation of his wheel. If he lets go the wheel, the motor is stopped. If he reverses it, the motor reverses. In testing the apparatus, it was at first found that when the current was cut off from the motor, the momentum of the armature carried it around for several revolutions, so that the weight being lifted or lowered was not brought to rest promptly. To remedy this, a magnetic brake has been applied to the armature shaft; the magnet coils of the brake (of very low resistance) are in series with the armature, and so long as a current is passing through the motor, the magnets are energized and the brake shoes are held away from the shaft. When the current is shut off, a heavy spiral spring at once draws the brake shoes together and the armature is stopped.
These first two applications of motors on board ship, the Chicago's gun-carriage motors and the Atlanta's shell-hoist, will doubtless receive much criticism in the service. Every new piece of mechanism does, and it is right and proper that they should receive such criticism, since naval officers know best what are the requirements and conditions on board ship. It is only fair, however, that a new device should receive a full and thorough trial, and that when a criticism is made, there is a corresponding desire to improve. We already see where certain parts about the shot-hoist can be improved upon in any future orders, tending to simplify it and decrease the space occupied. It is the universal experience with all mechanical appliances, that successive improvements in them always mean a reduction in number of parts and simplifying of motions.
The chief object aimed at in applying the training and elevating motors to the 8-inch gun-carriage is to increase the seed of moving the gun, and to enable the gun captain to follow the object aimed at nearly or quite as readily as is now done with the Hotchkiss single-shot gun. A single universal movement lever controls both motors. The gun captain trains right or left by moving lever to right or left; if he wishes to raise or lower the breech, he raises or lowers the lever. A combined motion of the lever will produce a combined motion of training and elevating or depressing. It would seem that with such a simple and complete control of his gun, a gun captain will be able to follow his target with almost, if not quite, the ease that he does with a 6-pounder Hotchkiss, since the motion of the gun is coincident with the motion of the man's hand, both in direction and in speed.
The application of a motor for steering purposes deserves special mention. It has been suggested to have a motor to operate the valve of the steam steerer only. While this would do away with the clumsy mechanical devices now necessary to transmit motion from the hand wheel to the engine, it is only a step in the right direction. The moving of the tiller itself should be accomplished by a motor. The system would then be a completed whole, and there would be a large saving in space, weight, noise, and heat. The same hand control, already mentioned in connection with the shell-hoist, would be most suitable for steering purposes. The motor moving the tiller follows the motion of the wheel in the hands of the helmsman, both in direction and speed. If he stops turning his wheel, the tiller stops in whatever position it may then occupy. This is analogous to the motion of the present steam steering engine. A pointer on the standard supporting the wheel indicates at any time the position of the tiller. It will be of interest to naval officers to know that the methods above described for adapting the electric motor to the handling of guns, steering and hoisting, are themselves the design of a naval officer, Lieutenant Bradley A. Fiske.
It will be seen from the foregoing remarks, that in introducing the motor on board ship, the navy will simply be following the experience and practice of commercial life, and there can be no reasonable doubt that the same advantages which have followed the introduction of the motor on shore will follow with even greater force its introduction on shipboard.
ELECTRIC RANGE FINDER.
One of the latest applications of electricity to nautical and military purposes is the range finder, also invented by Lieutenant Fiske. It is impossible at present to obtain the details of the apparatus, but it is known to consist of an electrical device by means of which the exact position of two telescopes at the ends of a base line of known length is automatically given. As applied to the Chicago and the Boston, the Bureau of Ordnance has insisted that the range finder shall give accurate indications of the distance of objects on any and all bearings, and that it shall not interfere in any way with the working of the ship or any part of its armament or equipment. It is expected that this invention will increase the ease and value of fleet evolutions, since every ship will have absolute knowledge of her distance from the others; and that it will lessen the dangers of coasting, since a vessel can plot her exact position as often as desired, having the means at hand for ascertaining both her distance and her bearing from any landmark, buoy, or lightship within sight. As an example of the accuracy of the instrument, it may be stated that the average error of twenty observations, half by night and half by day, was less than one per cent, the ranges varying from 500 yards to 2600 yards, the instrument being the first one constructed and necessarily crude.
SIGNALING BY ELECTRICITY.
One of the most serious problems to confront the commander-in-chief of a modern fleet or squadron is the transmission of signals in time of action to the vessels under his command. The enormous powder charges used in all modern high power guns create such a smoke after the first round is fired that signaling by flags, semaphores, etc., is out of the question. It has been suggested that it is a perfectly feasible plan to communicate between vessels by means of electricity, either by induction or by the direct action of an electric current. Two years ago, while attached to the Atlanta, I assisted Lieutenant Fiske in some interesting experiments of this nature. While the results obtained were not as successful in point of distance as we had expected, we did transmit signals from the Atlanta, then lying at the dock (New York Navy-yard), to the tug Nina, stationed in the Wallabout, there being no wire connection of any kind between the two vessels. The man receiving the signals had a pair of telephones at his ears, and the make and break of an ordinary telegraph key in circuit with the Atlanta's dynamo was distinctly heard. The results obtained would, at least, seem to warrant further experimenting in the same direction. A man receiving such messages by telephone could be stationed on the orlop or berth deck by himself, where he could be quiet, and he could then transmit them by speaking tube or telephone to the commanding officer.
Night signaling is now extensively done by electricity. The incandescent light offers a ready substitute for the torch or signal lantern in signaling between vessels that are within sight of one another. Devices for signaling by the incandescent lamp have already been devised and described. The search lights, however, offer a much more comprehensive system of signaling. Their powerful beam of light, when thrown into the sky, can be seen 20 or 30 miles away, and by having a quick-moving shutter or screen to cut off the light, the regular Morse code can readily be used in transmitting signals. Vessels separated by high land have thus communicated with each other and with forces on shore.
ELECTRIC ANNUNCIATORS, BELLS, GUN-FIRING CIRCUITS, ETC.
Electric communicators, bells, etc., have now reached such perfection and are so familiar to all that they need no description. They are largely used on all of our new vessels. The firing of the heavy guns by electricity, however, is a matter that should receive careful attention. Some experiments have already been made on board our older vessels, and new designs have been prepared for the Bureau of Ordnance for our new vessels which embody many improvements over the old system. While it may be true that the guns will ordinarily be fired by the gun captains, the commanding officer may nevertheless want control of the battery at a critical moment, and this is the time when the firing circuit will come in. It would certainly seem that the comparatively small outlay necessary for its installation would be well compensated for at such a time. Moreover, the gun captain himself should be able to fire his gun by electricity. An astronomer, when using a transit instrument, records the transit of the body observed on the chronograph by pressing an electric button. He uses electricity because he has got to record simultaneously with the transit of the body across the wires in the field of vision. Just so the gun captain should be able to press a key and fire his gun the instant his sights come on the object aimed at, and this can be accomplished by electricity better than by any other known method.
If electricity is to be introduced on board our war ships as generally as this paper contemplates, it is necessary that the navy co-operate heartily with the manufacturers in their endeavor to produce what is wanted, and I feel confident that all officers who have the best interests of the service at heart stand ready and willing to do so. The use of electricity means increased efficiency and economy in the operation of all auxiliary engines on board ship, and greater health and comfort for the officers and men.