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will perceive that when at rest, being entirely enclosed, time a cock, e, on a pipe opening from the chambers outits displacement of water being greater than its own wards, is opened, in order that, the air escaping, an unweight, it must float at the surface. Entering through interrupted flow of water may take place into the a man-hole at the top (which is closed either from the chambers. The assumption of weight of water causes a inside or outside), you descend into the interior of the destruction of buoyancy due to displacement by the mass machine, portions of which are walled off on either side, itself, and the Nautilus gradually sinks. As soon as it forming chambers; these chambers are connected at or is fairly under water, in order that the descent may be near the bottom by a pipe a,a, which opens by a cock b, quiet and without shock, the water cock, b, is closed. outwards to the external surrounding water. An opening The receiver at the surface, being previously charged by in the bottom of the machine of variable dimensions is the air-pump to a density somewhat greater than that of closed by a door or doors, susceptible of being opened or the water at the depth proposed to attain, one of the closed at pleasure. The chambers X,X, are likewise con- branch cocks on the pipe, c,c, connecting the chambers at nected at top by a smaller pipe c,c, which opens through top, is opened, and the air rushes into the working the top of the machine, and to which opening is affixed chamber, gradually condensing until a density equal to a flexible pipe, with coils of wire spirally enclosed. the density of the water without is attained; this is Branches on this latter pipe d,d, allow also communica-indicated by proper air and water guages, ff. These tion with the larger or working chamber. guages marking equal points, shewing the equilibrium of At the surface of the water, placed on a float or vessel forces without and within, the covers to the bottom, gg, for the purpose, is a receiver of variable dimensions, to are removed or raised, and communication is held with which is attached at one end a hollow drum or reel the bottom on which the Nautilus is resting. In order to to the barrel of which is affixed the other end of the move about in localities where tides or currents do not flexible pipe a, leading to the top of the Nautilus. At affect operations, it is only necessary to step out of the the other end of, and in connection with the receiver is bottom of the Nautilus, and placing the hands against its a powerful steam air-condensing pump. This combina-side the operator may move it (by pushing,) in any direc tion represents the Nautilus machine as adapted to en- tion. Where currents or tides, however, have sway, it gineering work.

As to the modus operandi.-The operator, with his assistants, enters the machine through the top, which is then closed. To descend, the water-cock b is opened, and the external water flows into the chambers, I,I; at the same

becomes necessary to depend upon fixed points from which movements may be made in any direction. This is accomplished by placing in the bottom of the Nautilus stuffing boxes of peculiar construction, k,k, through which cables may pass over pulleys to the external side, thence

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up through tubes, (to prevent them from being worn,) of the object suspended, so that it may be placed in any to and over oscillating or swinging pulleys placed in the required position. In the construction of permanent plane of the centre of gravity of the Nautilus, and thence works, or the movement of objects whose weight is to the points of affixment respectively. The object to known, or can be estimated, a water or so-called lifting be gained by having the swinging pulleys in the plane tube is placed on the side of the water chamber which of the centre of gravity of the mass, is to hold the indicates the lifting power exercised by the Nautilus at machine steady and to prevent oscillation. Within the any moment. The advantage of this guage will be machine, and directly over the above stuffing boxes, are recognised, inasmuch as (without it) the closest attenwindlasses for winding in the cables. By working these tion of the operator working very cautiously, would be windlasses movement may be effected, and of course the necessary to determine when the weight was overcome; number of these cables will depend on the variable by its aid however, the operator boldly throws open all character of the situation to be occupied. Having thus the valves necessary to develop the power of the Nautilus, secured the means of descending, communicating with watching only the guage. The water having reached the bottom, and of movement, the next point is to ascend. Weight of water has caused a destruction of buoyancy at first, and consequent sinking; if then, any portion of this water is removed, an upward effort will at once be exerted, exactly proportionate to the weight of water thrown off. The air in the receiver at the surface being constantly maintained at a higher density than that of the water below, if we open the water-cock, b, and at the same time open the cock on the top pipe, c,c, throwing the condensed air from the receiver above directly on to the surface of the water in the chambers, movement and consequent expulsion of the water must take place, and an upward movement of the machine itself, which will rise to the surface.

It is evident that if, previously to the expulsion of the water, the Nautilus be affixed to any object below, the power exerted on that object will be exactly proportionate to the weight of water expelled, and the power will continue increasing, until there being no further weight to be thrown off, the maximum effect is produced. To apply this power to lifting masses of stone or rock, proper arrangements are affixed to the centre of the opening in the bottom, by which connection can be made with the weight, admitting at the same time the swinging around

the proper level indicating the required lifting power, he knows the weight must be overcome or so nearly so, that the valve or the cocks may be at once closed, in order that the movement may take place horizontally. A moment's reflection will show, that if there were not an index of this character, carelessness or inattention on the part of the operator, by leaving the cocks open too long, might develop a power greater than required, and the Nautilus would start suddenly upward. The expansive power of air, acting upon the incompressible fluid water, through the opening in the bottom, gives a momentum, which by successive developments of expansion in the working chamber, is constantly increasing the velocity of the Nautilus upwards, until in any considerable depth of water, the result would be undoubtedly of a very serious character. Take for exemplification the Nautilus in 33 feet of water, the bottom covers removed, and an equilibrium at 15 pounds to the inch existing between the air and the water at the level of the bottom of the machine. Upward movement is communicated the instant the machine rises in the slightest degree, the existing equilibrium is destroyed, and the highly elastic qualities of air assume preponderance, exerting from the rigid surface of water below, an impulsive effort upward in the direc

tion of least resistance. At each successive moment of vice, either to examine the bottom previous to the locaupward movement, the impelling power increases, owing tion, or to commence the foundations at once. to the increased disparity between the pressure of air To speak now of that portion of the machinery which within struggling for escape, and the water without remains at the surface:-It is necessary in order to preventing that escape. The machine thus situated rapid movement, that the supply of air which, acting on becomes a marine rocket (in reality), in which the pro- the water in the water-chambers, causes the developpelling power is exhausted only when the surface is ment of the lifting power of the machine, should be in reached, and a new equilibrium is obtained. It will sufficient quantity, so that no delay may arise and that readily be seen, that were this difficulty not overcome, a constant supply may be continually afforded, that there it would be impossible to govern the Nautilus; for, rising may be no diminution of density in the receiver. It is with great velocity to the surface, the machine is carried also necessary that the density of the air in the receiver above its ordinary floatation or water-line; a little more should at all times be greater than that of the water at air escapes owing to the diminished resistance, as that the depth to which the machine descends, so that the level is passed; the recoil, or surging downwards, causes superior pressure of the air may produce instantaneous a condensation of the air remaining in the chamber; a movement of the water. A proper proportion of density portion of the space previously occupied by air is as in a receiver would be about one-third greater than that sumed by water, the buoyant power becomes less, the of the water. machine settles slightly more by condensation of the air, a larger space is occupied by water, and the Nautilus redescends to the bottom with a constantly accelerating movement, seriously inconveniencing the operators by filling more or less with water according to the depth. For many months the difficulties just enumerated baffled all attempts at control. A weight attached could be lifted, but the instant it was entirely suspended, before the valves could be closed, upward movement was com- There is no heating, owing to the rapid condensation municated entirely beyond control. This difficulty so of air at high density. The pumps will work confatal, has been overcome by an arrangement of the tinuously at the highest density, without any perbottom of the Nautilus, with channels which radiate ceptible increase of temperature. The economy of workfrom the opening in an inclined direction, debouching at ing several machines from the same or different rethe sides of the machine. The moment then, that the ceivers, supplied by one pump, is great, as the saving of air, by its expansion from diminished resistance, or by labour, fuel, wear and tear, in one engine over several, the introduction from above of a greater volume than is quite apparent; which economy is due in part to the can be sustained by the water below, reaches in its independence of suspension, allowing the receiver to be downward passage, the level of these chambers, follow-placed at any convenient point, even quite distant from the ing the direction of least resistance, it passes through Nautilus," inasmuch as the pipe inay be supported on these channels and escapes into the surrounding water, the surface of the water to the point over the work without of course affecting the movement of the machine itself. in the least.

The amount of air continually required for the respiratory purposes of the operators, and also for the purpose of lifting weights, demands a large supply, which is obtained from the steam-condensing pump directly to the receiver. The air-pumps are constructed to throw any required amount of air, each sufficient if required, to work two or three, or even more machines engaged in lifting heavy weights.

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Having the powers of air and water then at control, to I have thus, I trust, shown to you the principles on obviate the use of platforms, trucks, and carriage-way, which the engineering facilities of the nautilus depend. to lower stones into place, so that they may be properly First, on natural principles, from construction, it deposited, you may readily see that a caisson or float, must be independent of suspension; and here allow me properly arranged with regard to the relative centres of to bring forcibly to your minds the distinction between gravity and buoyancy may be moved over or near the a machine which, by its own power, may descend, as-work. A load of stone, according to the capacity of cend, move horizontally, lift weights, and transport them by itself (for 1 assume the operator to be a part of the machine), and the ordinary diving-bell so long used, by which we are enabled to perform the same operations, after much time spent in the preparation of piling, platforms, scaffolding, carriage.way, &c.; and where all necessary movements in the prosecution of the work must be made at the surface through the intervention of signals, which in all cases must be more or less liable to error and misunderstanding.

Supposing the same skilled and careful men to be placed under both conditions, the one time in the ordinary diving-bell, where, when they have determined on the necessary movements to be made, they signal to the surface, and await, first the proper underunderstanding of their wishes, and then subsequently, their execution by those who cannot know precisely the amount of assistance required; or another time, in a machine possessing the capabilities heretofore enumerated, by which the operator, having his work directly before him, watching all the varying circumstances which await his progress, foresees and applies directly his own hand to the work, governing and directing in person those operations which he requires to be performed-certainly the balance must be all in favour of the latter position.

Another thing in the case of the ordinary diving-bell, much time is necessarily consumed in making the necessary preperations to commence the use of the machine; in the other case, when once arrived at the spot required (if in the water), it is ready for immediate ser

the caisson, may be placed upon it. Having this caisson so arranged by divison into chambers, that the water cannot flow from side to side, and constructed with water valves and a connection with the receiver, when the load is properly placed upon it, and the water-valves opened, it will commence to sink. Regulating its descent slowly by the same process as the Nautilus itself, but governed from above, it may be placed in proper position, so that the least possible distance will be required to be passed over, in removing the stones so lowered to their ultimate position of permanency. As the weights are removed, it is obvious that more water will be required to be admitted, in order to retain the caisson at the bottom or on the work. The whole load being removed, to return to the surface, it will be merely necessary to throw from the receiver at the surface a portion of condensed air, to cause it to rise preparatory to its receiving a new load.

The comparative cost of lowering away stone in this manner, as contrasted with the ordinary crane, can hardly be doubted as being favourable to the first method, inasmuch as water is valueless, and the supply of air required to expel that water, as delivered from the condensing pump, can bear but a slight ratio of cost to the labour required to work the cranes. The cost of working a steam-condensing pump sufficient to lower as many stones as would supply two machines, as well as working the machines themselves, would not be more than thirty shillings per diem.

Where water transportation of material is afforded, the caissons themselves may be used as the means of

transportation of the stone from the quarry to the site of the work; and then fulfilling their real purpose, of depositing their load in the bottom. A great facility afforded by this process is, that there must always be a supply of material below, in advance of the requirements of the adjusting machines, so that no delay can arise by waiting for materials.

there left.

For removal of rocks: the facility that is afforded by going down directly on the bed of the rock, there drilling a series of holes, subsequently charging them, and then exploding them connectedly, would seem to be almost equal to that of the quarry. If large masses be detached, camels inflated, or charged from the receivers may be affixed to them (if too large for the nautilus itself,) and when lifted, towed to the place of deposit, and Manual labour alone can now be used below water; for steam, our great substitute, cannot be passed through so great a length of hose, and through varying temperature, as is necessary, without condensation; but air does not change its density by passing through great distances, or by any moderate change of temperature. Having a supply of air at the necessary density for a motive power, it may then be used as such, to propel the necessary drills for boring rocks, by having the proper engines placed within the "Nautilus," and exhausting to the surface. Air being at the same density as steam, and contained within the receivers, which are atmospheric boilers, we may apply the powers of air below, the same as steam at the surface, to the performance of any labour which may be required. There is no difference between air and steam at the same density in their application, except that in the use of air, which is a more subtle fluid than steam, we must exercise additional care in the arrangement of valves, &c. The powers of air which can be developed at the surface in any required amount, are not only applicable to the working of drills for boring rock, but for the sawing off of piles in the preparation of foundations, and for any other purpose where the application of manual labour at comparatively high cost, should if possible, be obviated.

To saw off piles for foundations. If one pile be driven or cut off at the requisite level, the Nautilus, which by construction retains its lower surface in a horizontal position, resting on that pile, and working a saw in the plane of that lower horizontal surface, will of necessity, cut all the piles with which it may be brought in contact in the same plane, then preparing the grillage and planking necessary, when lowered, the Nautilus passing over it can cause it to be securely affixed to the heads of the piles so cut off.

It is manifest that, unless very carefully arranged, any submerged vessel descending rapidly, and striking on any projecting object, would be liable to be thrown from its horizontal position, and to be overturned. Assume that the ordinary bell is descending, and strikes on a projecting or shelving rock, lowering away from the surface; unless the signals are distinctly understood, the chances would be very great of an overturn, resulting in great danger to those within.

depend on the distance apart of these two centres; therefore I may say, in a properly constructed machine an overturn could never be experienced.

This is a very important subject to be considered, for as there is no chain or rope to cause return to the surface, unless this point were thoroughly guarded there would be no safety at all, since if the Nautilus once received an inclination by the escape of air from the upper side and entrance of water on the lower side, the movement would increase until the whole might be overturned.

It would be unadvisable to say that any given amount of work could be performed by the Nautilus machine in a given time under all circumstances. The power of the machine is positive, and can be certainly relied on; but it may not always be possible to exert that power to its full extent. The length of time required to submerge a first-class machine, lifting six tons, will be two and onehalf minutes. Going down slowly, sixty feet per minute may be attained. While the machine is descending, the working chamber may be filled with air of the proper density to resist the entrance of water when the bottom cover is removed. Two minutes are sufficient to unclamp and raise the covers. If the object to be raised be immediately beneath, as soon as the necessary connections can be made, the water cocks are opened and the air is thrown into the water chambers, which can be entirely emptied giving its full lifting capacity of six tons in one-and-a-half minutes.

As to movement horizontally.-Every practical mind can form its own conclusions, as to the rapidity with which such a buoyant mass could be moved through the water. An extract from the report of Mr. Gay, Chief Engineer, U. S. Navy, to the Bureau of Docks and Yards will verify the statements I have made :

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:

With the assistance of two experienced persons, I descended in the bell to about twenty feet below the surface of the water. The time occupied to prepare the bell and reach the bottom was about two minutes and thirty seconds, and about a minute and-a-half to return to the surface. * * *

"One of several blocks of granite, weighing about four tons each, had been previously prepared, and placed on the bottom; the bell was attached to this stone by a 'Lewis.'

*

* * The time occupied in securing the stone and coming up was about three minutes. * * I descended with the stone, and, by the aid of two men, transported it several feet laterally, with as much ease as it could have been done were it suspended upon a crane, with the advantage of placing it at any point, or in any desired position."

By skilful and practised manipulation, the powers of any machinery must be developed in a greater degree than by unskilful handling. In acquiring the necessary skill, the necessary length of time required depends much on the complication of the principles involved, or the details by which the results are obtained. In working the Nautilus machine, it is not necessary that the operator should be a scientific man or practical mechanic. By the absolute control of natural elements, the will of the operator as it were, directs and governs the movements of the machine. It is thus the operations of the machine are comparatively inexpensive, since you are required to pay for labour alone, and not to compensate for the genius to comprehend or the skill to control a complicated and delicate instrument.

In the case where no suspension exists, it becomes necessary to overcome any such tendency to danger, which is done by so harmonizing the centres of buoyancy and of gravity, that under no circumstances can there be but a very slight deflection from a horizontal position. Gravity acts downwards and buoyancy up- In any paper description of a new system, of whatever wards, both in vertical lines. Construct a machine nature it may be, it is impossible to enter into sufficient symmetrically, then, with the centres of gravity and buoy-detail to enable the mind at a single glance, or by a ancy in the same vertical line, the one near the bottom, on account of weight, the other by peculiarity of construction, as far removed as possible from the first, or as near the top as may be. If, by any means the horizontal position should be destroyed, both forces at once act to restore its original or correct state, gravity downwards, buoyancy upwards; and the power or effective lever which tends to restore it to this horizontal state, will

single hearing, to fully comprehend all or even most of the advantages claimed, or of the disadvantages which may be found apparent. In the case however of the system which I have the honour of presenting to you, as applied to submarine engineering, based as it is on purely natural principles, whose partial application heretofore has been attended with a degree of success, certainly of a satis factory character, the principles laid down I trust, are

so easily understood that no one can fail to admit that, then be signalled to work, to restore the volume of air
certainly if the principles in their adaptation in the Nau- and drive back the water. Oscillation too is dangerous,
tilus, are governed as represented, the value of the im-if at all of a serious character, for the masons may be
provements thus made must be of great practical impor- injured in their limbs if standing on the bottom with the
tance to the engineer, by rendering his labours free from bell suspended. The mason knows too, that if the chain,
much anxiety, and enabling him with confidence to on which rests his entire hope of safety should break,
undertake works of peculiar characteristics of position, that the chances are almost certain that his life is lost
which, previously considered, would have seemed hazard-(numerous instances have attested this latter point); the
weight is too great for him to attempt to raise it, and
I cannot flatter myself that in this system, a sovereign his workshop furnishes him with a metallic coffin. It is
panacea has been discovered for all the dangerous symp-evident that no man, however daring he may be, can
toms which the engineer meets with in the practice of work with so much will where the chances of danger,
his profession under water; but I trust that you will however remote, are independent of his own power of
admit, that certainly his toils may be rendered lighter, governance, as he can where he feels that his own will
his risks diminished, his expenditures curtailed, his time can at any moment remove him from the possibility of
saved by this process.
danger.

ous.

In reascending to the surface after the completion of duty below, the movement must necessarily be very slow, owing to the same reasons previously enumerated in lowering away. If the chain break while ascending, where would be the labourer's chance?

Enough of the difficulties below. There are stilldangers and difficulties at the surface. A storm arises— the work is in an exposed situation-and a portion is weakened, perhaps carried away.

The necessary time must be taken to strengthen or reconstruct the damaged portions. This involves time, it involves expense.

A sketch of the construction of a work, by present process, and by the use of the Nautilus may be permitted me. We will suppose the location selected, and that the impracticability of constructing a coffer dam has rendered necessary the use of the ordinary diving bell, which we will also suppose, is already constructed and ready for use. The first step will be to commence driving the piles upon which the scaffolding is to rest; the scaffolding must then be constructed; the rails must be laid for the passage of the suspending trucks; these trucks must then be placed in position and prepared for use. The bell is then suspended, and we will suppose is ready for work, a considerable amount of time having been ex- We will now suppose a position, as the removal of a pended in this preparation. The bell is raised out of the rock, or the construction of a pier-foundation, &c., where water, the masons enter, and are lowered away. The it is impracticable to construct platforms and stagings. descent must be slow, for the weight is great, the chains A boat from which to suspend a bell must be used. Any are stiff, and manual labour is required to overcome these motion communicated to this boat at the surface, must difficulties. Then too, being open at the bottom, lower-cause the oscillation below which I have previously ing away can be effected only as fast as air is supplied by the pumps from above to resist the encroachment of water. The bottom is reached and work is commenced. Movement is necessary-signals are made by blows on the side of the bell, or by the signal cord-at the same time the signal is made and understood at the surface, they commence to move the whole apparatus as directed; the truck at the surface and the bell below move together. It is desired to stop; before doing so, new signals are necessary, movements below being restricted in their efficiency by the proper understanding of signals. You wish to move slightly only, you are carried too far and

must return.

spoken of as greatly retarding or entirely putting a stop
to operations while such motion is experienced.

Take now the location where the coffer dam is adopted. The first step is to construct the dam, which is a work of time, which is an expense. The dam however being completed and free from leakage, of course the work can then be carried on with great rapidity; but there are difficulties even here; springs in some cases cause difficulties; leaks too, arise. A storm, by weakening a portion of the dam, may cause a delay for repairs or even may demand an entire reconstruction. Of course to the mind of everyone present this is but a suggestion of some of the difficulties which in all cases, in a greater or less degree, attend the construction of this class of works. There is no need of bringing them forward except to place them in contrast with any means which may miti

In the preparation of foundations where in many cases it is required to move often from point to point in excavating or levelling, this delay becomes important. The foundations, however, are prepared, and the super-gate their action in whole or in part. structure is commenced. A stone is lowered. The bell by signal is moved over it, and they are connected ;signal to the surface, and the weight of the bell and the stone must be raised together;-signal again to stop hoisting;-signal to move in or out, right or left ;movement is made;-the spot is reached, and the stone must be deposited precisely. The mason says a little to the right, but he cannot say how many inches and he gets too far; then by successive movements by signal he is accurately placed and lowered away. Then to place another stone he goes through the same process. Mark the time consumed here from want of independence. He sees the stone; he knows it must go there, in that spot, but he cannot himself exercise the power necessary to place it there, but must wait the pleasure and understanding of his directions by others, who of course can only have a general idea of his wishes.

In this way the work is carried on. Other difficulties are however, in the way. The bell suspended below is a pendulum of variable length; if the water be rough at the surface, a swaying or oscillating movement is given to the pendulum, which, in its oscillation however alight, disturbs the horizontal equilibrium between the air and the water, and the air escapes from the upper side, and water enters on the lower side. The pump must

To contrast the action of the Nautilus and to see how far by its action, as previously described, these difficulties may be overcome, I will suppose as in the case of the ordinary bell, the location is decided on. And first, before a decision upon that point is arrived at, you will undoubtedly recognize the facility which the engineer possesses by its use in descending himself, and by accurate survey determining the most favourable position for such location. The nature of the foundation required being determined, its preparation may be at once commenced, since, towing the Nautilus to the spot, your workmen are ready at once to commence work at the same time that, in the other case, they commence the driving piles for the scaffolding. While the scaffolds are being erected, it is but fair to suppose that great progress may have been made by the Nautilus in the construction of the work itself. Í have previously shown that, being in position, but a very few moments are required for the workmen to reach the bottom. They then see their work and are ready to prosecute it. No signals for movement are necessary; they wish to move an inch, a foot, a rod, it is done at once; there is no restraining influence, which is not subject to their own will. When their labours are ended they themselves return to the surface, as rapidly or as slowly as they please.

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